当前期刊: FEMS Microbiology Reviews Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Antibiotic resistance: turning evolutionary principles into clinical reality
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2020-01-25
    Andersson D, Balaban N, Baquero F, et al.

    ABSTRACTAntibiotic resistance is one of the major challenges facing modern medicine worldwide. The past few decades have witnessed rapid progress in our understanding of the multiple factors that affect the emergence and spread of antibiotic resistance at the population level and the level of the individual patient. However, the process of translating this progress into health policy and clinical practice has been slow. Here, we attempt to consolidate current knowledge about the evolution and ecology of antibiotic resistance into a roadmap for future research as well as clinical and environmental control of antibiotic resistance. At the population level, we examine emergence, transmission and dissemination of antibiotic resistance, and at the patient level, we examine adaptation involving bacterial physiology and host resilience. Finally, we describe new approaches and technologies for improving diagnosis and treatment and minimizing the spread of resistance.

    更新日期:2020-01-26
  • The Shewanella genus: ubiquitous organisms sustaining and preserving aquatic ecosystems
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2020-01-10
    Lemaire O, Méjean V, Iobbi-Nivol C.

    The Gram-negative Shewanella bacterial genus currently includes about 70 species of mostly aquatic γ­proteobacteria, which were isolated around the globe in a multitude of environments such as surface freshwater and the deepest marine trenches. Their survival in such a wide range of ecological niches is due to their impressive physiological and respiratory versatility. Some strains are among the organisms with the highest number of respiratory systems, depending on a complex and rich metabolic network. Implicated in the recycling of organic and inorganic matter, they are important components of organism-rich oxic/anoxic interfaces, but they also belong to the microflora of a broad group of eukaryotes from metazoans to green algae. Examples of long-term biological interactions like mutualism or pathogeny have been described, although molecular determinants of such symbioses are still poorly understood. Some of these bacteria are key organisms for various biotechnological applications, especially the bioremediation of hydrocarbons and metallic pollutants. The natural ability of these prokaryotes to thrive and detoxify deleterious compounds explains their use in wastewater treatment, their use in energy generation by microbial fuel cells, and their importance for resilience of aquatic ecosystems.

    更新日期:2020-01-10
  • Development of a vaccine against Staphylococcus aureus invasive infections: Evidence-based on human immunity, genetics, and bacterial evasion mechanisms
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2019-12-16
    Miller L, Fowler V, Jr, Shukla S, et al.

    Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.

    更新日期:2019-12-17
  • Structure and genetics of Escherichia coli O antigens
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2019-11-28
    Liu B, Furevi A, Perepelov A, et al.

    Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and four (O14, O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.

    更新日期:2019-11-29
  • How bacteria recognise and respond to surface contact
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2019-11-26
    Kimkes T, Heinemann M.

    Bacterial biofilms can cause medical problems and issues in technical systems. While a large body of knowledge exists on the phenotypes of planktonic and of sessile cells in mature biofilms, our understanding of what happens when bacteria change from the planktonic to the sessile state is still very incomplete. Fundamental questions are unanswered: for instance, how do bacteria sense that they are in contact with a surface, and what are the very initial cellular responses to surface contact. Here, we review the current knowledge on the signals that bacteria could perceive once they attach to a surface, the signal transduction systems that could be involved in sensing the surface contact, and the cellular responses that are triggered as a consequence to surface contact ultimately leading to biofilm formation. Finally, as the main obstacle in investigating the initial responses to surface contact has been the difficulty to experimentally study the dynamic response of single cells upon surface attachment, we also review recent experimental approaches that could be employed to study bacterial surface sensing, which ultimately could lead to an improved understanding how biofilm formation could be prevented.

    更新日期:2019-11-27
  • Gardnerella and vaginal health: the truth is out there
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2019-11-07
    Rosca A, Castro J, Sousa L, et al.

    The human vagina is a dynamic ecosystem in which homeostasis depends on mutually beneficial interactions between the host and their microorganisms. However, the vaginal ecosystem can be thrown off balance by a wide variety of factors. Bacterial vaginosis (BV) is the most common vaginal infection in women of childbearing age, but its etiology is not yet fully understood, with different controversial theories being raised over the years. What is generally accepted is that BV is often characterized by a shift in the composition of the normal vaginal microbiota, from a Lactobacillus species dominated microbiota to a mixture of anaerobic and facultative anaerobic bacteria. During BV, a polymicrobial biofilm develops in the vaginal microenvironment, being mainly composed of Gardnerella species. The interactions between vaginal microorganisms are thought to play a pivotal role in the shift from health to disease and might also increase the risk of sexually transmitted infections acquisition. Here we review the current knowledge regarding the specific interactions that occur in the vaginal niche and discuss mechanisms by which these interactions might be mediated. Furthermore, we discuss the importance of novel strategies to fight chronic vaginal infections.

    更新日期:2019-11-08
  • Metal limitation and toxicity at the interface between host and pathogen.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2014-09-12
    Kyle W Becker,Eric P Skaar

    Metals are required cofactors for numerous fundamental processes that are essential to both pathogen and host. They are coordinated in enzymes responsible for DNA replication and transcription, relief from oxidative stress, and cellular respiration. However, excess transition metals can be toxic due to their ability to cause spontaneous, redox cycling and disrupt normal metabolic processes. Vertebrates have evolved intricate mechanisms to limit the availability of some crucial metals while concurrently flooding sites of infection with antimicrobial concentrations of other metals. To compete for limited metal within the host while simultaneously preventing metal toxicity, pathogens have developed a series of metal regulatory, acquisition, and efflux systems. This review will cover the mechanisms by which pathogenic bacteria recognize and respond to host-induced metal scarcity and toxicity.

    更新日期:2019-11-01
  • Experimental evolution in biofilm populations.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2017-02-16
    Hans P Steenackers,Ilse Parijs,Akanksha Dubey,Kevin R Foster,Jozef Vanderleyden

    更新日期:2019-11-01
  • Exceptionally widespread nanomachines composed of type IV pilins: the prokaryotic Swiss Army knives.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2015-03-21
    Jamie-Lee Berry,Vladimir Pelicic

    Prokaryotes have engineered sophisticated surface nanomachines that have allowed them to colonize Earth and thrive even in extreme environments. Filamentous machineries composed of type IV pilins, which are associated with an amazing array of properties ranging from motility to electric conductance, are arguably the most widespread since distinctive proteins dedicated to their biogenesis are found in most known species of prokaryotes. Several decades of investigations, starting with type IV pili and then a variety of related systems both in bacteria and archaea, have outlined common molecular and structural bases for these nanomachines. Using type IV pili as a paradigm, we will highlight in this review common aspects and key biological differences of this group of filamentous structures.

    更新日期:2019-11-01
  • Physical stress and bacterial colonization.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2014-09-13
    Michael Otto

    Bacterial surface colonizers are subject to a variety of physical stresses. During the colonization of human epithelia such as on the skin or the intestinal mucosa, bacteria mainly have to withstand the mechanical stress of being removed by fluid flow, scraping, or epithelial turnover. To that end, they express a series of molecules to establish firm attachment to the epithelial surface, such as fibrillar protrusions (pili) and surface-anchored proteins that bind to human matrix proteins. In addition, some bacteria--in particular gut and urinary tract pathogens--use internalization by epithelial cells and other methods such as directed inhibition of epithelial turnover to ascertain continued association with the epithelial layer. Furthermore, many bacteria produce multilayered agglomerations called biofilms with a sticky extracellular matrix, providing additional protection from removal. This review will give an overview over the mechanisms human bacterial colonizers have to withstand physical stresses with a focus on bacterial adhesion.

    更新日期:2019-11-01
  • Chlamydial metabolism revisited: interspecies metabolic variability and developmental stage-specific physiologic activities.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2014-02-04
    Anders Omsland,Barbara Susanne Sixt,Matthias Horn,Ted Hackstadt

    Chlamydiae are a group of obligate intracellular bacteria comprising important human and animal pathogens as well as symbionts of ubiquitous protists. They are characterized by a developmental cycle including two main morphologically and physiologically distinct stages, the replicating reticulate body and the infectious nondividing elementary body. In this review, we reconstruct the history of studies that have led to our current perception of chlamydial physiology, focusing on their energy and central carbon metabolism. We then compare the metabolic capabilities of pathogenic and environmental chlamydiae highlighting interspecies variability among the metabolically more flexible environmental strains. We discuss recent findings suggesting that chlamydiae may not live as energy parasites throughout the developmental cycle and that elementary bodies are not metabolically inert but exhibit metabolic activity under appropriate axenic conditions. The observed host-free metabolic activity of elementary bodies may reflect adequate recapitulation of the intracellular environment, but there is evidence that this activity is biologically relevant and required for extracellular survival and maintenance of infectivity. The recent discoveries call for a reconsideration of chlamydial metabolism and future in-depth analyses to better understand how species- and stage-specific differences in chlamydial physiology may affect virulence, tissue tropism, and host adaptation.

    更新日期:2019-11-01
  • Phenol-soluble modulins--critical determinants of staphylococcal virulence.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2014-01-01
    Gordon Y C Cheung,Hwang-Soo Joo,Som S Chatterjee,Michael Otto

    Phenol-soluble modulins (PSMs) are a recently discovered family of amphipathic, alpha-helical peptides that have multiple roles in staphylococcal pathogenesis and contribute to a large extent to the pathogenic success of virulent staphylococci, such as Staphylococcus aureus. PSMs may cause lysis of many human cell types including leukocytes and erythrocytes, stimulate inflammatory responses, and contribute to biofilm development. PSMs appear to have an original role in the commensal lifestyle of staphylococci, where they facilitate growth and spreading on epithelial surfaces. Aggressive, cytolytic PSMs seem to have evolved from that original role and are mainly expressed in highly virulent S. aureus. Here, we will review the biochemistry, genetics, and role of PSMs in the commensal and pathogenic lifestyles of staphylococci, discuss how diversification of PSMs defines the aggressiveness of staphylococcal species, and evaluate potential avenues to target PSMs for drug development against staphylococcal infections.

    更新日期:2019-11-01
  • DNA replication fidelity in Escherichia coli: a multi-DNA polymerase affair.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2012-03-13
    Iwona J Fijalkowska,Roel M Schaaper,Piotr Jonczyk

    High accuracy (fidelity) of DNA replication is important for cells to preserve the genetic identity and to prevent the accumulation of deleterious mutations. The error rate during DNA replication is as low as 10(-9) to 10(-11) errors per base pair. How this low level is achieved is an issue of major interest. This review is concerned with the mechanisms underlying the fidelity of the chromosomal replication in the model system Escherichia coli by DNA polymerase III holoenzyme, with further emphasis on participation of the other, accessory DNA polymerases, of which E. coli contains four (Pols I, II, IV, and V). Detailed genetic analysis of mutation rates revealed that (1) Pol II has an important role as a back-up proofreader for Pol III, (2) Pols IV and V do not normally contribute significantly to replication fidelity, but can readily do so under conditions of elevated expression, (3) participation of Pols IV and V, in contrast to that of Pol II, is specific to the lagging strand, and (4) Pol I also makes a lagging-strand-specific fidelity contribution, limited, however, to the faithful filling of the Okazaki fragment gaps. The fidelity role of the Pol III τ subunit is also reviewed.

    更新日期:2019-11-01
  • Microbial antigenic variation mediated by homologous DNA recombination.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2012-01-04
    Cornelis Vink,Gloria Rudenko,H Steven Seifert

    Pathogenic microorganisms employ numerous molecular strategies in order to delay or circumvent recognition by the immune system of their host. One of the most widely used strategies of immune evasion is antigenic variation, in which immunogenic molecules expressed on the surface of a microorganism are continuously modified. As a consequence, the host is forced to constantly adapt its humoral immune response against this pathogen. An antigenic change thus provides the microorganism with an opportunity to persist and/or replicate within the host (population) for an extended period of time or to effectively infect a previously infected host. In most cases, antigenic variation is caused by genetic processes that lead to the modification of the amino acid sequence of a particular antigen or to alterations in the expression of biosynthesis genes that induce changes in the expression of a variant antigen. Here, we will review antigenic variation systems that rely on homologous DNA recombination and that are found in a wide range of cellular, human pathogens, including bacteria (such as Neisseria spp., Borrelia spp., Treponema pallidum, and Mycoplasma spp.), fungi (such as Pneumocystis carinii) and parasites (such as the African trypanosome Trypanosoma brucei). Specifically, the various DNA recombination-based antigenic variation systems will be discussed with a focus on the employed mechanisms of recombination, the DNA substrates, and the enzymatic machinery involved.

    更新日期:2019-11-01
  • The molecular basis of herpes simplex virus latency.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2011-12-14
    Michael P Nicoll,João T Proença,Stacey Efstathiou

    Herpes simplex virus type 1 is a neurotropic herpesvirus that establishes latency within sensory neurones. Following primary infection, the virus replicates productively within mucosal epithelial cells and enters sensory neurones via nerve termini. The virus is then transported to neuronal cell bodies where latency can be established. Periodically, the virus can reactivate to resume its normal lytic cycle gene expression programme and result in the generation of new virus progeny that are transported axonally back to the periphery. The ability to establish lifelong latency within the host and to periodically reactivate to facilitate dissemination is central to the survival strategy of this virus. Although incompletely understood, this review will focus on the mechanisms involved in the regulation of latency that centre on the functions of the virus-encoded latency-associated transcripts (LATs), epigenetic regulation of the latent virus genome and the molecular events that precipitate reactivation.

    更新日期:2019-11-01
  • Growth rate regulation in Escherichia coli.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2011-05-17
    Ding Jun Jin,Cedric Cagliero,Yan Ning Zhou

    Growth rate regulation in bacteria has been an important issue in bacterial physiology for the past 50 years. This review, using Escherichia coli as a paradigm, summarizes the mechanisms for the regulation of rRNA synthesis in the context of systems biology, particularly, in the context of genome-wide competition for limited RNA polymerase (RNAP) in the cell under different growth conditions including nutrient starvation. The specific location of the seven rrn operons in the chromosome and the unique properties of the rrn promoters contribute to growth rate regulation. The length of the rrn transcripts, coupled with gene dosage effects, influence the distribution of RNAP on the chromosome in response to growth rate. Regulation of rRNA synthesis depends on multiple factors that affect the structure of the nucleoid and the allocation of RNAP for global gene expression. The magic spot ppGpp, which acts with DksA synergistically, is a key effector in both the growth rate regulation and the stringent response induced by nutrient starvation, mainly because the ppGpp level changes in response to environmental cues. It regulates rRNA synthesis via a cascade of events including both transcription initiation and elongation, and can be explained by an RNAP redistribution (allocation) model.

    更新日期:2019-11-01
  • Base pairing small RNAs and their roles in global regulatory networks.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2010-07-29
    Chase L Beisel,Gisela Storz

    Bacteria use a range of RNA regulators collectively termed small RNAs (sRNAs) to help respond to changes in the environment. Many sRNAs regulate their target mRNAs through limited base-pairing interactions. Ongoing characterization of base-pairing sRNAs in bacteria has started to reveal how these sRNAs participate in global regulatory networks. These networks can be broken down into smaller regulatory circuits that have characteristic behaviors and functions. In this review, we describe the specific regulatory circuits that incorporate base-pairing sRNAs and the importance of each circuit in global regulation. Because most of these circuits were originally identified as network motifs in transcriptional networks, we also discuss why sRNAs may be used over protein transcription factors to help transduce environmental signals.

    更新日期:2019-11-01
  • Managing membrane stress: the phage shock protein (Psp) response, from molecular mechanisms to physiology.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2010-07-20
    Nicolas Joly,Christoph Engl,Goran Jovanovic,Maxime Huvet,Tina Toni,Xia Sheng,Michael P H Stumpf,Martin Buck

    The bacterial phage shock protein (Psp) response functions to help cells manage the impacts of agents impairing cell membrane function. The system has relevance to biotechnology and to medicine. Originally discovered in Escherichia coli, Psp proteins and homologues are found in Gram-positive and Gram-negative bacteria, in archaea and in plants. Study of the E. coli and Yersinia enterocolitica Psp systems provides insights into how membrane-associated sensory Psp proteins might perceive membrane stress, signal to the transcription apparatus and use an ATP-hydrolysing transcription activator to produce effector proteins to overcome the stress. Progress in understanding the mechanism of signal transduction by the membrane-bound Psp proteins, regulation of the psp gene-specific transcription activator and the cell biology of the system is presented and discussed. Many features of the action of the Psp system appear to be dominated by states of self-association of the master effector, PspA, and the transcription activator, PspF, alongside a signalling pathway that displays strong conditionality in its requirement.

    更新日期:2019-11-01
  • Mechanisms for activating bacterial RNA polymerase.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2010-07-16
    Tamaswati Ghosh,Daniel Bose,Xiaodong Zhang

    Gene transcription is a fundamental cellular process carried out by RNA polymerase (RNAP) enzymes and is highly regulated through the action of gene regulatory complexes. Important mechanistic insights have been gained from structural studies on multisubunit RNAP from bacteria, yeast and archaea, although the initiation process that involves the conversion of the inactive transcription complex to an active one has yet to be fully understood. RNAPs are unambiguously closely related in structure and function across all kingdoms of life and have conserved mechanisms. In bacteria, sigma (sigma) factors direct RNAP to specific promoter sites and the RNAP/sigma holoenzyme can either form a stable closed complex that is incompetent for transcription (as in the case of sigma(54)) or can spontaneously proceed to an open complex that is competent for transcription (as in the case of sigma(70)). The conversion of the RNAP/sigma(54) closed complex to an open complex requires ATP hydrolysis by enhancer-binding proteins, hence providing an ideal model system for studying the initiation process biochemically and structurally. In this review, we present recent structural studies of the two major bacterial RNAP holoenzymes and focus on mechanistic advances in the transcription initiation process via enhancer-binding proteins.

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Regulatory RNAs in photosynthetic cyanobacteria.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2015-05-03
    Matthias Kopf,Wolfgang R Hess

    Regulatory RNAs play versatile roles in bacteria in the coordination of gene expression during various physiological processes, especially during stress adaptation. Photosynthetic bacteria use sunlight as their major energy source. Therefore, they are particularly vulnerable to the damaging effects of excess light or UV irradiation. In addition, like all bacteria, photosynthetic bacteria must adapt to limiting nutrient concentrations and abiotic and biotic stress factors. Transcriptome analyses have identified hundreds of potential regulatory small RNAs (sRNAs) in model cyanobacteria such as Synechocystis sp. PCC 6803 or Anabaena sp. PCC 7120, and in environmentally relevant genera such as Trichodesmium, Synechococcus and Prochlorococcus. Some sRNAs have been shown to actually contain μORFs and encode short proteins. Examples include the 40-amino-acid product of the sml0013 gene, which encodes the NdhP subunit of the NDH1 complex. In contrast, the functional characterization of the non-coding sRNA PsrR1 revealed that the 131 nt long sRNA controls photosynthetic functions by targeting multiple mRNAs, providing a paradigm for sRNA functions in photosynthetic bacteria. We suggest that actuatons comprise a new class of genetic elements in which an sRNA gene is inserted upstream of a coding region to modify or enable transcription of that region.

    更新日期:2019-11-01
  • Control of genes for conjugative transfer of plasmids and other mobile elements.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1998-01-01
    M Zatyka,C M Thomas

    Conjugative transfer is a primary means of spread of mobile genetic elements (plasmids and transposons) between bacteria.It leads to the dissemination and evolution of the genes (such as those conferring resistance to antibiotics) which are carried by the plasmid. Expression of the plasmid genes needed for conjugative transfer is tightly regulated so as to minimise the burden on the host. For plasmids such as those belonging to the IncP group this results in downregulation of the transfer genes once all bacteria have a functional conjugative apparatus. For F-like plasmids (apart from F itself which is a derepressed mutant) tight control results in very few bacteria having a conjugative apparatus. Chance encounters between the rare transfer-proficient bacteria and a potential recipient initiate a cascade of transfer which can continue until all potential recipients have acquired the plasmid. Other systems express their transfer genes in response to specific stimuli. For the pheromone-responsive plasmids of Enterococcus it is small peptide signals from potential recipients which trigger the conjugative transfer genes. For the Ti plasmids of Agrobacterium it is the presence of wounded plants which are susceptible to infection which stimulates T-DNA transfer to plants. Transfer and integration of T-DNA induces production of opines which the plasmid-positive bacteria can utilise. They multiply and when they reach an appropriate density their plasmid transfer system is switched on to allow transfer of the Ti plasmid to other bacteria. Finally some conjugative transfer systems are induced by the antibiotics to which the elements confer resistance. Understanding these control circuits may help to modify management of microbial communities where plasmid transfer is either desirable or undesirable. z 1998 Published by Elsevier Science B.V.

    更新日期:2019-11-01
  • The role of iron in Campylobacter gene regulation, metabolism and oxidative stress defense.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2002-06-19
    Arnoud H M van Vliet,Julian M Ketley,Simon F Park,Charles W Penn

    Enteric Campylobacter species cause gastrointestinal diseases in humans. Like almost all organisms, campylobacters have an absolute requirement for iron, but are faced with variable availability of iron in the environment and host tissues. Campylobacters have developed mechanisms to scavenge sufficient iron for metabolism and growth. However, iron also participates in the formation of reactive oxygen species, and this forces pathogens to maintain intracellular iron homeostasis and to cope with oxidative stresses. The presence of two separate, but possibly overlapping iron-responsive regulatory systems, which regulate iron acquisition and oxidative stress defense, and the presence of genes encoding multiple iron acquisition and detoxification systems in Campylobacter indicate the central role that iron plays in Campylobacter gene regulation and virulence.

    更新日期:2019-11-01
  • Halobacterial adenosine triphosphatases and the adenosine triphosphatase from Halobacterium saccharovorum.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1986-01-01
    H Kristjansson,M H Sadler,L I Hochstein

    Membranes prepared from various members of the genus Halobacterium contained a Triton X-100 activated adenosine triphosphatase. The enzyme from Halobacterium saccharovorum was unstable in solutions of low ionic strength (< 3 M NaCl) and maximally active in the presence of 3.5 M NaCl. A variety of nucleotide triphosphates was hydrolyzed. MgADP, the product of ATP hydrolysis, was not hydrolyzed and was a competitive inhibitor with respect to MgATP. The enzyme from H. saccharovorum was composed of at least 2 and possibly 4 subunits. The 83-kDa and 60-kDa subunits represented about 90% of total protein. The 60-kDa subunit reacted with dicyclohexylcarbodiimide (DCCD) when inhibition was carried out in an acidic medium. The significance of the two minor components (28 kDa and 12 kDa is not established. The enzyme from H. saccharovorum, which differs from previously described halobacterial ATPases, possesses properties of an F1F0 as well as an E1E2 ATPase.

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Adhesin-receptor interactions in Pasteurellaceae.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1998-06-26
    M Jacques,S E Paradis

    The ability of bacteria to adhere to mucosal epithelium is dependent on the expression of adhesive molecules or structures, called adhesins, that allow attachment of the organisms to complementary molecules on mucosal surfaces, the receptors. Important human and animal pathogens are found among the Pasteurellaceae family which includes Haemophilus, Actinobacillus, and Pasteurella organisms. The purpose of this paper is to review the adhesin-receptor systems found in Pasteurellaceae, with an emphasis on recent developments in this specific area. Most of these organisms can employ multiple molecular mechanisms of adherence (or multiple adhesins) to initiate infection. Indeed, a wide variety of adhesins are expressed by members of the Pasteurellaceae, and different proteins (e.g. fimbriae, fibrils, outer membrane proteins) as well as polysaccharides (lipooligosaccharides, lipopolysaccharides, capsular polysaccharides) were clearly shown to play an important role in adherence. In many instances, these adhesins have proved to represent good vaccine candidates. Surprisingly, the receptors on host mucosal surfaces have yet been identified in very few cases.

    更新日期:2019-11-01
  • Tungsten in biological systems.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1996-03-01
    A Kletzin,M W Adams

    Tungsten (atomic number 74) and the chemically analogous and very similar metal molybdenum (atomic number 42) are minor yet equally abundant elements on this planet. The essential role of molybdenum in biology has been known for decades and molybdoenzymes are ubiquitous. Yet, it is only recently that a biological role for tungsten has been established in prokaryotes, although not as yet in eukaryotes. The best characterized organisms with regard to their metabolism of tungsten are certain species of hyperthermophilic archaea (Pyrococcus furiosus and Thermococcus litoralis), methanogens (Methanobacterium thermoautotrophicum and Mb. wolfei), Gram-positive bacteria (Clostridium thermoaceticum, C. formicoaceticum and Eubacterium acidaminophilum), Gram-negative anaerobes (Desulfovibrio gigas and Pelobacter acetylenicus) and Gram-negative aerobes (Methylobacterium sp. RXM). Of these, only the hyperthermophilic archaea appear to be obligately tungsten-dependent. Four different types of tungstoenzyme have been purified: formate dehydrogenase, formyl methanufuran dehydrogenase, acetylene hydratase, and a class of phylogenetically related oxidoreductases that catalyze the reversible oxidation of aldehydes. These are carboxylic reductase, and three ferredoxin-dependent oxidoreductases which oxidize various aldehydes, formaldehyde and glyceraldehyde 3-phosphate. All tungstoenzymes catalyze redox tungsten in these enzymes is bound by a pterin moiety similar to that found in molybdoenzymes. The first crystal structure of a tungsten- or pterin-containing enzyme, that of aldehyde ferredoxin oxidoreductase from P. furiosus, has revealed a catalytic site with one W atom coordinated to two pterin molecules which are themselves bridged by a magnesium ion. The geochemical, ecological, biochemical and phylogenetic basis for W- vs. Mo-dependent organisms is discussed.

    更新日期:2019-11-01
  • Genetics of Paracoccus denitrificans.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1993-01-01
    P Steinrücke,B Ludwig

    In bioenergetic research Paracoccus denitrificans has been used as an interesting model to elucidate the mechanisms of bacterial energy transduction. Genes for protein complexes of the respiratory chain and for proteins which are involved in periplasmic electron transport have been cloned and sequenced. Conjugational gene transfer has allowed the construction of site-specific mutant strains. Complementation experiments did not only open the field for site-directed mutagenesis and investigation of the structure/function relationship of the various electron-transport proteins, but also allowed first insights into processes like oxygen-dependent gene regulation or the assembly of electron-transport complexes. Also data will be presented that characterize two restriction-/modification systems, the codon usage and the promoter sequences of Paracoccus. Details will be given about the extrachromosomal localization of a duplicated cytochrome oxidase subunit I gene on one of the Paracoccus megaplasmids.

    更新日期:2019-11-01
  • Sugar transport in Saccharomyces cerevisiae.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1993-04-01
    R Lagunas

    The yeast Saccharomyces cerevisiae consumes mono- and disaccharides preferentially to any other carbon source. Since sugars do not freely permeate biological membranes, cellular uptake of these compounds requires the action of 'transporters'. The purpose of this review is to summarize the present knowledge on sugar transport in this organism. Yeast cells show two transporters for monosaccharides, the so-called glucose and galactose transporters that act by a facilitated diffusion mechanism. In the case of glucose transport, which also acts upon D-fructose and D-mannose, two components with high- and low-affinity constants have been identified kinetically. Activity of the high-affinity component is dependent on the presence of active kinases whereas activity of the low-affinity component is independent of the presence of these enzymes. Three genes, SNF3, HXT1 and HXT2, encode three different glucose transporters with a high affinity for the substrates and are repressed by high concentrations of glucose in the medium. Kinetic studies suggest that at least one additional gene exists that encodes a transporter with a low affinity and is expressed constitutively. The present view is that there are several additional transporters for glucose that have not yet been identified. Galactose transport has only one natural substrate, D-galactose, and is encoded by the gene GAL2. Expression of this gene is induced by galactose and repressed by glucose. Two transporters for disaccharides have been identified in S. cerevisiae: maltose and alpha-methylglucoside transporters. These transporters are H(+)-symports that depend on the electrochemical proton gradient and are independent of the ATP level. The gene that encodes the maltose transporter is clustered with the other two genes required for maltose utilization in a locus that is found repeated at different chromosomal locations. Its expression is induced by maltose and repressed by glucose. The rate of sugar uptake in yeast cells is controlled by changes in affinity of the corresponding transporters as well as by an irreversible inactivation that affects their Vmax. The mechanisms involved in these regulatory processes are unknown at present.

    更新日期:2019-11-01
  • The nitrite oxidizing system of Nitrobacter winogradskyi.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1988-12-01
    T Yamanaka,Y Fukumori

    Cytochrome components which participate in the oxidation of nitrite in Nitrobacter winogradskyi have been highly purified and their properties studied in detail. Cytochrome a1c1 is an iron-sulphur molybdoenzyme which has haems a and c and acts as a nitrite-cytochrome c oxidoreductase. Cytochrome c-550 is homologous to eukaryotic cytochrome c and acts as the electron mediator between cytochrome a1c1 and aa3-type cytochrome c oxidase. The oxidase is composed of two kinds of subunits, has two molecules of haem a and two atoms of copper in the molecule, and oxidizes actively eukaryotic ferrocytochrome c as well as its own ferrocytochrome c-550. Further, a flavoenzyme has been obtained which has transhydrogenase activity and catalyses reduction of NADP+ with benzylviologen radical. This enzyme may be responsible for production of NADPH in N. winogradskyi. The electron transfer against redox potential from NO2- to cytochrome c could be pushed through prompt removal by cytochrome aa3 of H+ formed by the dehydrogenation of NO2- + H2O. As cytochrome c in anaerobically kept cell-free extracts is rapidly reduced on addition of NO2-, a membrane potential does not seem necessary for the reduction of cytochrome c by cytochrome a1c1 with NO2- in vivo.

    更新日期:2019-11-01
  • Molecular mechanisms of bacterial chemotaxis towards PTS-carbohydrates.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    J W Lengeler,A P Vogler

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Genetics of the PTS components in Escherichia coli K-12.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    H De Reuse,S Lévy,G Zeng,A Danchin

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • 更新日期:2019-11-01
  • 更新日期:2019-11-01
  • 更新日期:2019-11-01
  • 更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Glucose transport in Escherichia coli.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    B Erni

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Peptidases and proteases of Escherichia coli and Salmonella typhimurium.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-09-01
    A M Lazdunski

    A number of peptidases and proteases have been identified in Escherichia coli. Although their specific physiological roles are often not known, some of them have been shown to be involved in: the maturation of nascent polypeptide chains; the maturation of protein precursors; the signal peptide processing of exported proteins; the degradation of abnormal proteins; the use of small peptides as nutrients; the degradation of colicins; viral morphogenesis; the inactivation of some regulatory proteins for which a limited lifetime is a physiological necessity. Some of these enzymes act in concert to carry out specific functions. At present, twelve peptidases and seventeen proteases have been characterized. The specificity for only a few of them is known. The possible roles and the properties of these enzymes are discussed in this review.

    更新日期:2019-11-01
  • Microbial metabolism of short-chain unsaturated hydrocarbons.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-09-01
    S Hartmans,J A de Bont,W Harder

    更新日期:2019-11-01
  • The fermentation pathways of Escherichia coli.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-09-01
    D P Clark

    Under anaerobic conditions and in the absence of alternative electron acceptors Escherichia coli converts sugars to a mixture of products by fermentation. The major soluble products are acetate, ethanol, acetate and formate with smaller amounts of succinate. In addition the gaseous products hydrogen and carbon dioxide are produced in substantial amounts. The pathway generating fermentation products is branched and the flow down each branch is varied in response both to the pH of the culture medium and the nature of the fermentation substrate. In particular, the ratio of the various fermentation products is manipulated in order to balance the number of reducing equivalents generated during glycolytic breakdown of the substrate. The enzymes and corresponding genes involved in these fermentation pathways are described. The regulatory responses of these genes and enzymes are known but the details of the underlying regulatory mechanisms are still obscure.

    更新日期:2019-11-01
  • Carbon metabolism and catabolite repression in Rhizobium spp.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    F O'Gara,K Birkenhead,B Boesten,A M Fitzmaurice

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Diversity of glucose entry routes in the Enterobacteriaceae.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    P A Grimont,O M Bouvet

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Genetics of the phosphotransferase system of Bacillus subtilis.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    A Fouet,M Arnaud,A Klier,G Rapoport

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Molecular details of Escherichia coli EIImtl catalyzed mannitol transport and phosphorylation.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-06-01
    G T Robillard,H H Pas,R H ten Hoeve-Duurkens,M G Elferink

    更新日期:2019-11-01
  • The -24/-12 promoter comes of age.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1989-12-01
    B Thöny,H Hennecke

    A new bacterial promoter type has been identified in the last few years. Originally designated as nif (= nitrogen fixation) or ntr (= nitrogen regulation) consensus promoter, it is now evident that this promoter occurs in many different bacterial species and is used not only for genes involved in nitrogen assimilation but also for genes determining many other unrelated metabolic functions. The general features of this type of promoter are (i) the conserved -24(GG)/-12(GC) consensus sequence, (ii) its recognition by a specific RNA polymerase sigma factor, sigma 54, which is encoded by the ntrA gene (synonyms: glnF, rpoN, rpoE), and (iii) the requirement for a transcriptional regulatory protein to activate the expression of the associated genes. In addition, many (but not all) of these genes possess a promoter-upstream activator sequence (enhancer) which is the target site for the binding of the activating protein and is required for maximal expression. In some cases, in which gene expression does not appear to be dependent on the presence of upstream binding sites, the activating protein may interact directly with the RNA polymerase-promoter complex. In conclusion, the expression from all -24/-12 consensus promoters known to date is positively controlled.

    更新日期:2019-11-01
  • Molecular genetics of Streptococcus thermophilus.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1990-09-01
    A Mercenier

    The metabolism and genetics of Streptococcus thermophilus (presently Streptococcus salivarius ssp. thermophilus) have only been investigated recently despite its widespread use in milk fermentation processes. The development of recombinant DNA technology has allowed impressive progress to be made in the knowledge of thermophilic dairy streptococci. In particular, it has permitted a careful analysis of phenotypically altered variants which were derived from a mother strain by plasmid or chromosomal DNA reorganization. While natural phage defense mechanisms of S. thermophilus remain poorly documented, information on the bacteriophages responsible for fermentation failures has accumulated. The lysogenic state of two S. thermophilus strains has also been demonstrated for the first time. Gene transfer techniques for this species have been established and improved to the point that targeted manipulation of their chromosomal determinants is now feasible. Cloning and expression vectors have been constructed, and a few heterologous genes were successfully expressed in S. thermophilus. The first homologous genes, involved in carbohydrate utilization, have been cloned and sequenced, shedding some light on the molecular organization of key metabolic steps.

    更新日期:2019-11-01
  • Formyl-methanofuran synthesis in Methanobacterium thermoautotrophicum.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1990-12-01
    T A Bobik,A A DiMarco,R S Wolfe

    The initial step of methanogenesis from CO2 is the formation of formyl-methanofuran (formyl-MFR) from methanofuran (MFR), CO2 and H2. The enzymology of this novel type of CO2 fixation reaction has been difficult to study because formyl-MFR synthesis is subject to a complex activation. Recently, however, a number of advances have made questions regarding formyl-MFR synthesis more approachable.

    更新日期:2019-11-01
  • Molecular biology studies of the uptake hydrogenase of Rhodobacter capsulatus and Rhodocyclus gelatinosus.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1990-12-01
    P Richaud,P M Vignais,A Colbeau,R L Uffen,B Cauvin

    In the photosynthetic bacteria, as in other N2-fixing bacteria, two main enzymes are involved in H2 metabolism: nitrogenase, which catalyses the photoproduction of H2, and a membrane-bound (NiFe) hydrogenase, which functions as an H2-uptake enzyme. The structural genes for Rhodobacter capsulatus and Rhodocyclus gelatinosus uptake hydrogenases were isolated and sequenced. They present the same organization, with the gene encoding the small subunit (hupS) (molecular masses 34.2 and 34.6 kDa, respectively) preceding the gene encoding the large one (hupL) (molecular masses 65.8 and 68.5 kDa, respectively). The two hupSL genes apparently belong to the same operon. The deduced protein sequences of the small and of the large subunits share nearly 80% and maximally 70% identity, respectively, with their counterparts in uptake hydrogenases found in N2-fixing bacteria. However, unlike in Bradyrhizobium japonicum, R. gelatinosus or Azotobacter chroococcum, another open reading frame (ORFX) was found downstream and contiguous to the R. capsulatus hupSL whose transcription seemed to depend on the same hup promoter as hupSL. ORFX contained 786 nucleotides capable of encoding a hydrophobic polypeptide of 262 amino acids (30.2 kDa).

    更新日期:2019-11-01
  • Intracellular degradation of poly(3-hydroxybutyrate) granules of Zoogloea ramigera I-16-M.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1992-12-01
    T Saito,H Saegusa,Y Miyata,T Fukui

    Intracellular degradation of poly(3-hydroxybutyrate) (PHB) in bacteria is not yet clear. The properties of the autodigestion of native PHB granules from Zoogloea ramigera I-16-M were examined. The release of D(-)-3-hydroxybutyrate was observed only at pH values higher than about 8.5 and at relatively high ionic strength (optimal concentration 200 mM NaCl). Triton X-100 and diisopropylfluorophosphate inhibited this reaction. Addition of the supernatant fraction of Z. ramigera did not increase the release of D(-)-3-hydroxybutyrate from the native PHB granules. On the other hand, using the protease-treated PHB granules from Alcaligenes eutrophus as a substrate, PHB depolymerase activity was detected in the supernatant fraction of Z. ramigera cells. The soluble PHB depolymerase showed similar properties to the enzyme in the PHB granules. Since PHB depolymerase activity was found in fractions containing D(-)-3-hydroxybutyrate oligomer hydrolase activity, which were separated by DEAE-Toyopearl or by Sephacryl S-100, it is possible that the intracellular PHB depolymerase is identical to the oligomer hydrolase which has been purified already.

    更新日期:2019-11-01
  • Polyhydroxyalkanoate production in recombinant Escherichia coli.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1992-12-01
    S Fidler,D Dennis

    The bacterial species Escherichia coli has proven to be a powerful tool in the molecular analysis of polyhydroxyalkanoate (PHA) biosynthesis. In addition, E. coli holds promise as a source for economical PHA production. Using this microorganism, clones have been developed in our laboratory which direct the synthesis of poly-beta-hydroxybutyrate (PHB) to levels as high as 95% of the cell dry weight. These clones have been further enhanced by the addition of a genetically mediated lysis system that allows the PHB granules to be released gently and efficiently. This paper describes these developments, as well as the use of an E. coli strain to produce the copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-3HV).

    更新日期:2019-11-01
  • Protein secretion in Pseudomonas aeruginosa.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1992-09-01
    J Tommassen,A Filloux,M Bally,M Murgier,A Lazdunski

    The Gram-negative bacterium Pseudomonas aeruginosa secretes many proteins into the extracellular medium. At least two distinct secretion pathways can be discerned. The majority of the exoproteins are secreted via a two-step mechanism. These proteins are first translocated across the inner membrane in a signal sequence-dependent fashion. The subsequent translocation across the outer membrane requires the products of at least 12 distinct xcp genes. The exact role of one of these proteins, the XcpA protein, has been resolved. It is a peptidase that is required for the processing of the precursors of four other Xcp proteins, thus allowing their assembly into the secretion apparatus. This peptidase is also required for the processing of the precursors of type IV pili subunits. Two other Xcp proteins, XcpR and XcpS, display extensive homology to proteins involved in pili biogenesis, which suggests that the assembly of the secretion apparatus and the biogenesis of type IV pili are related processes. The secretion of alkaline protease does not require the xcp gene products. This enzyme, which is encoded by the aprA gene, is not synthesized in a precursor form with an N-terminal signal sequence. Secretion across the two membranes probably takes place in one step at adhesion zones that may be constituted by three accessory proteins, designated AprD, AprE and AprF. The two secretion pathways found in P. aeruginosa appear to have disseminated widely among Gram-negative bacteria.

    更新日期:2019-11-01
  • Principles of functional and structural organization in the bacterial cell: 'compartments' and their enzymes.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 1993-04-01
    F Mayer

    Most bacteria lack obvious compartmentation, i.e., structural partition of the cell into functional entities (organelles) formed by a closed biological membrane. Nevertheless, these organisms exhibit sophisticated regulation and interactions of their catabolic and anabolic pathways; they are able to exploit a great variety of carbon and energy sources, and they conserve and transform energy in an efficient manner. In a less stringent sense, 'compartments' are also present in bacteria if one accepts that bacterial 'compartments' are not necessarily surrounded by a membrane, but are rather defined as mere functional entities characterized by their structural components, their enzymes and other functional proteins such as binding proteins. This view would mean that the bacterial cell can be described as a highly organized structured system comprised of these functional entities. Regulated transport processes within 'compartments' and across boundaries involving low and high molecular mass compounds, solutes, and ions take place within the 'framework' constituted by this structured system. Special emphasis is given to the fact that many of the transport processes take place involving the functional entity 'energized membrane'. This 'framework', the structural basis for the functional potential of a bacterial cell, can be studied by electron microscopy. Advanced sample preparation techniques and imaging modes are available which keep the danger of artefact formation low; they can be applied at cellular and macromolecular levels. Recent developments in immunoelectron microscopy and affinity labelling techniques provide tools which allow to unequivocally locate enzymes and other antigens in the cell and to identify polypeptide chains in enzyme complexes. Application of these approaches in studies on cellular and macromolecular organization of bacteria and their enzyme systems confirmed some old views but also extended our knowledge. This is exemplified by a description of selected enzyme complexes located in the bacterial cytoplasm, in the cytoplasmic membrane or attached to it, in the periplasmic space, and attached to the cell wall or set free into the surrounding medium.

    更新日期:2019-11-01
  • Beneficial lactobacilli in food and feed: long-term use, biodiversity and proposals for specific and realistic safety assessments.
    FEMS Microbiol. Rev. (IF 11.524) Pub Date : 2006-06-16
    Marion Bernardeau,Micheline Guguen,Jean Paul Vernoux

    Lactobacilli have played a crucial role in the production of fermented products for millennia. Their probiotic effects have recently been studied and used in new products. Isolated cases of lactobacillemia have been reported in at-risk populations, but lactobacilli present an essentially negligible biological risk. We analyzed the current European guidelines for safety assessment in food/feed and conclude that they are not relevant for the Lactobacillus genus. We propose new specific guidelines, beginning by granting a 'long-standing presumption of safety' status to Lactobacillus genus based on its long history of safe use. Then, based on the available body of knowledge and intended use, only such tests as are useful will be necessary before attributing 'qualified presumption of safety' status.

    更新日期:2019-11-01
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug