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  • Regulation of virulence of Entamoeba histolytica.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2014-07-09
    Chelsea Marie,William A Petri

    Entamoeba histolytica is the third-leading cause of parasitic mortality globally. E. histolytica infection generally does not cause symptoms, but the parasite has potent pathogenic potential. The origins, benefits, and triggers of amoebic virulence are complex. Amoebic pathogenesis entails depletion of the host mucosal barrier, adherence to the colonic lumen, cytotoxicity, and invasion of the colonic epithelium. Parasite damage results in colitis and, in some cases, disseminated disease. Both host and parasite genotypes influence the development of disease, as do the regulatory responses they govern at the host-pathogen interface. Host environmental factors determine parasite transmission and shape the colonic microenvironment E. histolytica infects. Here we highlight research that illuminates novel links between host, parasite, and environmental factors in the regulation of E. histolytica virulence.

    更新日期:2019-11-01
  • Opportunities for genetic investigation afforded by Acinetobacter baylyi, a nutritionally versatile bacterial species that is highly competent for natural transformation.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2005-09-13
    David M Young,Donna Parke,L Nicholas Ornston

    The genetic and physiological properties of Acinetobacter baylyi strain ADP1 make it an inviting subject for investigation of the properties underlying its nutritional versatility. The organism possesses a relatively small genome in which genes for most catabolic functions are clustered in several genetic islands that, unlike pathogenicity islands, give little evidence of horizontal transfer. Coupling mutagenic polymerase chain reaction to natural transformation provides insight into how structure influences function in transporters, transcriptional regulators, and enzymes. With appropriate selection, mutants in which such molecules have acquired novel function may be obtained. The extraordinary competence of A. baylyi for natural transformation and the ease with which it expresses heterologous genes make it a promising platform for construction of novel metabolic systems. Steps toward this goal should take into account the complexity of existing pathways in which transmembrane trafficking plays a significant role.

    更新日期:2019-11-01
  • The development of bacterial resistance to chemotherapeutic agents.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    C P MILLER,M BOHNHOFF

    更新日期:2019-11-01
  • Prions and the potential transmissibility of protein misfolding diseases.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2013-07-03
    Allison Kraus,Bradley R Groveman,Byron Caughey

    Prions, or infectious proteins, represent a major frontier in the study of infectious agents. The prions responsible for mammalian transmissible spongiform encephalopathies (TSEs) are due primarily to infectious self-propagation of misfolded prion proteins. TSE prion structures remain ill-defined, other than being highly structured, self-propagating, and often fibrillar protein multimers with the capacity to seed, or template, the conversion of their normal monomeric precursors into a pathogenic form. Purified TSE prions usually take the form of amyloid fibrils, which are self-seeding ultrastructures common to many serious protein misfolding diseases such as Alzheimer's, Parkinson's, Huntington's and Lou Gehrig's (amytrophic lateral sclerosis). Indeed, recent reports have now provided evidence of prion-like propagation of several misfolded proteins from cell to cell, if not from tissue to tissue or individual to individual. These findings raise concerns that various protein misfolding diseases might have spreading, prion-like etiologies that contribute to pathogenesis or prevalence.

    更新日期:2019-11-01
  • Structure and operation of bacterial tripartite pumps.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2013-07-03
    Philip Hinchliffe,Martyn F Symmons,Colin Hughes,Vassilis Koronakis

    In bacteria such as Pseudomonas aeruginosa and Escherichia coli, tripartite membrane machineries, or pumps, determine the efflux of small noxious molecules, such as detergents, heavy metals, and antibiotics, and the export of large proteins including toxins. They are therefore influential in bacterial survival, particularly during infections caused by multidrug-resistant pathogens. In these tripartite pumps an inner membrane transporter, typically an ATPase or proton antiporter, binds and translocates export or efflux substrates. In cooperation with a periplasmic adaptor protein it recruits and opens a TolC family cell exit duct, which is anchored in the outer membrane and projects across the periplasmic space between inner and outer membranes. Assembled tripartite pumps thus span the entire bacterial cell envelope. We review the atomic structures of each of the three pump components and discuss how these have allowed high-resolution views of tripartite pump assembly, operation, and possible inhibition.

    更新日期:2019-11-01
  • Vaccines to prevent infections by oncoviruses.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2010-04-28
    John T Schiller,Douglas R Lowy

    It has been estimated that viruses are etiological agents in approximately 12% of human cancers. Most of these cancers can be attributed to infections by human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein-Barr virus (EBV), and Kaposi's sarcoma-associated herpesvirus (KSHV). Prophylactic vaccines against other pathogenic viruses have an excellent record as public health interventions in terms of safety, effectiveness, and ability to reach economically disadvantaged populations. These considerations should prompt efforts to develop and implement vaccines against oncoviruses. Safe and effective HBV and HPV vaccines, based on virus-like particles, are commercially available, and the major focus is now on vaccine delivery, especially to low-resource settings. HCV and EBV vaccines are under active development, but few clinical trials have been conducted, and none of the candidate vaccines has proven to be sufficiently effective to warrant commercialization. Efforts to develop KSHV vaccines have been more limited.

    更新日期:2019-11-01
  • Photorhabdus and a host of hosts.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2009-07-07
    Nick R Waterfield,Todd Ciche,David Clarke

    Photorhabdus is a member of the family Enterobacteriaceae that lives in a mutualistic association with a Heterorhabditis nematode worm. The nematode worm burrows into insect prey and regurgitates Photorhabdus, which goes on to kill the insect. The nematode feeds off the growing bacteria until the insect tissues are exhausted, whereupon they reassociate and leave the cadaver in search of new prey. This highly efficient partnership has been used for many years as a biological crop protection agent. The dual nature of Photorhabdus as a pathogen and mutualist makes it a superb model for understanding these apparently exclusive activities. Furthermore, recently identified clinical isolates of Photorhabdus are helping us to understand how human pathogens can emerge from the enormous reservoir of invertebrate pathogens in the environment. As Photorhabdus has never been found outside a host animal, its niche represents an entirely biotic landscape. In this review we discuss what molecular adaptations allow this bacterium to complete this fascinating and complex life cycle.

    更新日期:2019-11-01
  • Regulation and function of Ag43 (flu).
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2008-09-13
    Marjan W van der Woude,Ian R Henderson

    Antigen 43 (Ag43) is an abundant outer membrane protein in Escherichia coli belonging to the autotransporter family. Structure-function relationships of Ag43 proposed on the basis of experimental work and in silico analysis are discussed in context of insights derived from molecular modeling. New sequence analysis sheds light on the phylogeny of the allelic variants of the Ag43-encoding gene and identifies two distinct families that appear to be distributed between specific pathogenic and commensal isolates. The molecular mechanism that controls expression by phase variation to create population heterogeneity is discussed. Proposed roles of Ag43 expression for E. coli are summarized and the studies are put into perspective regarding the role of allelic variants, genetic background of the bacterial strain, and control of expression by phase variation. We conclude that future studies need to take into account these variables to obtain a complete understanding of the contribution of Ag43 expression to E. coli biology.

    更新日期:2019-11-01
  • Viral subversion of apoptotic enzymes: escape from death row.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2008-08-30
    Sonja M Best

    To prolong cell viability and facilitate replication, viruses have evolved multiple mechanisms to inhibit the host apoptotic response. Cellular proteases such as caspases and serine proteases are instrumental in promoting apoptosis. Thus, these enzymes are logical targets for virus-mediated modulation to suppress cell death. Four major classes of viral inhibitors antagonize caspase function: serpins, p35 family members, inhibitor of apoptosis proteins, and viral FLICE-inhibitory proteins. Viruses also subvert activity of the serine proteases, granzyme B and HtrA2/Omi, to avoid cell death. The combined efforts of viruses to suppress apoptosis suggest that this response should be avoided at all costs. However, some viruses utilize caspases during replication to aid virus protein maturation, progeny release, or both. Hence, a multifaceted relationship exists between viruses and the apoptotic response they induce. Examination of these interactions contributes to our understanding of both virus pathogenesis and the regulation of apoptotic enzymes in normal cellular functions.

    更新日期:2019-11-01
  • Subterfuge and sabotage: evasion of host innate defenses by invasive gram-positive bacterial pathogens.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2014-07-09
    Cheryl Y M Okumura,Victor Nizet

    The development of a severe invasive bacterial infection in an otherwise healthy individual is one of the most striking and fascinating aspects of human medicine. A small cadre of gram-positive pathogens of the genera Streptococcus and Staphylococcus stand out for their unique invasive disease potential and sophisticated ability to counteract the multifaceted components of human innate defense. This review illustrates how these leading human disease agents evade host complement deposition and activation, impede phagocyte recruitment and activation, resist the microbicidal activities of host antimicrobial peptides and reactive oxygen species, escape neutrophil extracellular traps, and promote and accelerate phagocyte cell death through the action of pore-forming cytolysins. Understanding the molecular basis of bacterial innate immune resistance can open new avenues for therapeutic intervention geared to disabling specific virulence factors and resensitizing the pathogen to host innate immune clearance.

    更新日期:2019-11-01
  • Introduction: Remembering Olaf Schneewind.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : null
    Susan Gottesman

    更新日期:2019-11-01
  • Introduction.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2018-09-12
    Susan Gottesman

    更新日期:2019-11-01
  • Introduction.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2017-09-10
    Susan Gottesman

    更新日期:2019-11-01
  • The importance of microbes in animal development: lessons from the squid-vibrio symbiosis.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2014-07-06
    Margaret J McFall-Ngai

    Developmental biology is among the many subdisciplines of the life sciences being transformed by our increasing awareness of the role of coevolved microbial symbionts in health and disease. Most symbioses are horizontally acquired, i.e., they begin anew each generation. In such associations, the embryonic period prepares the animal to engage with the coevolved partner(s) with fidelity following birth or hatching. Once interactions are underway, the microbial partners drive maturation of tissues that are either directly associated with or distant from the symbiont populations. Animal alliances often involve complex microbial communities, such as those in the vertebrate gastrointestinal tract. A series of simpler-model systems is providing insight into the basic rules and principles that govern the establishment and maintenance of stable animal-microbe partnerships. This review focuses on what biologists have learned about the developmental trajectory of horizontally acquired symbioses through the study of the binary squid-vibrio model.

    更新日期:2019-11-01
  • Ligand-binding PAS domains in a genomic, cellular, and structural context.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2011-06-15
    Jonathan T Henry,Sean Crosson

    Per-Arnt-Sim (PAS) domains occur in proteins from all kingdoms of life. In the bacterial kingdom, PAS domains are commonly positioned at the amino terminus of signaling proteins such as sensor histidine kinases, cyclic-di-GMP synthases/hydrolases, and methyl-accepting chemotaxis proteins. Although these domains are highly divergent at the primary sequence level, the structures of dozens of PAS domains across a broad section of sequence space have been solved, revealing a conserved three-dimensional architecture. An all-versus-all alignment of 63 PAS structures demonstrates that the PAS domain family forms structural clades on the basis of two principal variables: (a) topological location inside or outside the plasma membrane and (b) the class of small molecule that they bind. The binding of a chemically diverse range of small-molecule metabolites is a hallmark of the PAS domain family. PAS ligand binding either functions as a primary cue to initiate a cellular signaling response or provides the domain with the capacity to respond to secondary physical or chemical signals such as gas molecules, redox potential, or photons. This review synthesizes the current state of knowledge of the structural foundations and evolution of ligand recognition and binding by PAS domains.

    更新日期:2019-11-01
  • Adaptive mutation: the uses of adversity.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1993-01-01
    P L Foster

    When populations of microorganisms are subjected to certain nonlethal selections, useful mutants arise among the nongrowing cells whereas useless mutants do not. This phenomenon, known as adaptive, directed, or selection-induced mutation, challenges the long-held belief that mutations only arise at random and without regard for utility. In recent years a growing number of studies have examined adaptive mutation in both bacteria and yeast. Although conflicts and controversies remain, the weight of the evidence indicates that adaptive mutation cannot be explained by trivial artifacts and that nondividing cells accumulate mutations in the absence of genomic replication. Because this process tends to produce only useful mutations, the cells appear to have a mechanism for preventing useless genetic changes from occurring or for eliminating them after they occur. The model that most readily explains the evidence is that cells under stress produce genetic variants continuously and at random, but these variants are immortalized as mutations only if they allow the cell to grow.

    更新日期:2019-11-01
  • Lipoteichoic acid synthesis and function in gram-positive bacteria.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2014-05-14
    Matthew G Percy,Angelika Gründling

    Lipoteichoic acid (LTA) is an important cell wall polymer found in gram-positive bacteria. Although the exact role of LTA is unknown, mutants display significant growth and physiological defects. Additionally, modification of the LTA backbone structure can provide protection against cationic antimicrobial peptides. This review provides an overview of the different LTA types and their chemical structures and synthesis pathways. The occurrence and mechanisms of LTA modifications with D-alanyl, glycosyl, and phosphocholine residues will be discussed along with their functions. Similarities between the production of type I LTA and osmoregulated periplasmic glucans in gram-negative bacteria are highlighted, indicating that LTA should perhaps be compared to these polymers rather than lipopolysaccharide, as is presently the case. Lastly, current efforts to use LTAs as vaccine candidates, synthesis proteins as novel antimicrobial targets, and LTA mutant strains as improved probiotics are highlighted.

    更新日期:2019-11-01
  • Microbial population and community dynamics on plant roots and their feedbacks on plant communities.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2012-06-26
    James D Bever,Thomas G Platt,Elise R Morton

    The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology.

    更新日期:2019-11-01
  • Influence of nutrition in experimental infection.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    P F CLARK

    更新日期:2019-11-01
  • Brucellosis.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    M R CASTANEDA

    更新日期:2019-11-01
  • The immunology of the human mycoses.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    A M KLIGMAN,E D DeLAMATER

    更新日期:2019-11-01
  • Tularemia.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    L FOSHAY

    更新日期:2019-11-01
  • Immunological reactions in viral diseases.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    H KOPROWSKI

    更新日期:2019-11-01
  • Antibiosis in relation to plant diseases.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    R WEINDLING,H KATZNELSON,H P BEALE

    更新日期:2019-11-01
  • Chemotherapy of virus and rickettsial infections.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    M D EATON

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Genetics of viruses.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    F B GORDON

    更新日期:2019-11-01
  • Genetics of microorganisms.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    E L TATUM,D D PERKINS

    更新日期:2019-11-01
  • Newer antibiotics.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    W E HERRELL

    更新日期:2019-11-01
  • Bacterial metabolism.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    L O KRAMPITZ

    更新日期:2019-11-01
  • Mutualisms in protozoa.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    R E HUNGATE

    更新日期:2019-11-01
  • Constituents of mycobacteria.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    F B SEIBERT

    更新日期:2019-11-01
  • Bacteriophages.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1950-01-01
    T F ANDERSON

    更新日期:2019-11-01
  • 更新日期:2019-11-01
  • Kaposi's sarcoma-associated herpesvirus immunoevasion and tumorigenesis: two sides of the same coin?
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Patrick S Moore,Yuan Chang

    Kaposi's sarcoma-associated herpesvirus (KSHV) [or human herpesvirus 8 (HHV-8)] is the most frequent cause of malignancy among AIDS patients. KSHV and related herpesviruses have extensively pirated cellular cDNAs from the host genome, providing a unique opportunity to examine the range of viral mechanisms for controlling cell proliferation. Many of the viral regulatory homologs encode proteins that directly inhibit host adaptive and innate immunity. Other viral proteins target retinoblastoma protein and p53 control of tumor suppressor pathways, which also play key effector roles in intracellular immune responses. The immune evasion strategies employed by KSHV, by targeting tumor suppressor pathways activated during immune system signaling, may lead to inadvertent cell proliferation and tumorigenesis in susceptible hosts.

    更新日期:2019-11-01
  • Bacterial biofilms: an emerging link to disease pathogenesis.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Matthew R Parsek,Pradeep K Singh

    The role of biofilms in the pathogenesis of some chronic human infections is now widely accepted. However, the criteria used to determine whether a given infection is caused by biofilms remain unclear. In this chapter we discuss three infections that are caused by biofilms--infectious kidney stones, bacterial endocarditis, and cystic fibrosis lung infections--and focus on the role of the biofilm in disease pathogenesis. Biofilms are also important as environmental reservoirs for pathogens, and the biofilm growth mode may provide organisms with survival advantages in natural environments and increase their virulence. The consequences of pathogens living in environmental biofilms and an analysis of some specific environmental biofilm systems are presented.

    更新日期:2019-11-01
  • The secret lives of the pathogenic mycobacteria.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Christine L Cosma,David R Sherman,Lalita Ramakrishnan

    Pathogenic mycobacteria, including the causative agents of tuberculosis and leprosy, are responsible for considerable morbidity and mortality worldwide. A hallmark of these pathogens is their tendency to establish chronic infections that produce similar pathologies in a variety of hosts. During infection, mycobacteria reside in macrophages and induce the formation of granulomas, organized immune complexes of differentiated macrophages, lymphocytes, and other cells. This review summarizes our understanding of Mycobacterium-host cell interactions, the bacterial-granuloma interface, and mechanisms of bacterial virulence and persistence. In addition, we highlight current controversies and unanswered questions in these areas.

    更新日期:2019-11-01
  • DNA mismatch repair: molecular mechanisms and biological function.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Mark J Schofield,Peggy Hsieh

    DNA mismatch repair (MMR) guards the integrity of the genome in virtually all cells. It contributes about 1000-fold to the overall fidelity of replication and targets mispaired bases that arise through replication errors, during homologous recombination, and as a result of DNA damage. Cells deficient in MMR have a mutator phenotype in which the rate of spontaneous mutation is greatly elevated, and they frequently exhibit microsatellite instability at mono- and dinucleotide repeats. The importance of MMR in mutation avoidance is highlighted by the finding that defects in MMR predispose individuals to hereditary nonpolyposis colorectal cancer. In addition to its role in postreplication repair, the MMR machinery serves to police homologous recombination events and acts as a barrier to genetic exchange between species.

    更新日期:2019-11-01
  • The bacterial RecA protein as a motor protein.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Michael M Cox

    The bacterial RecA protein plays a central role in the repair of stalled replication forks, double-strand break repair, general recombination, induction of the SOS response, and SOS mutagenesis. The major activity of RecA in DNA metabolism is the promotion of DNA strand exchange reactions. RecA is the prototype for a ubiquitous family of proteins but exhibits a few activities that some of its eukaryotic, archaeal, and viral homologs appear to lack. In particular, the bacterial RecA protein possesses an apparent motor function that is not evident in the reactions promoted by the eukaryotic Rad51 protein. This motor may be needed only in a subset of the DNA metabolism contexts in which RecA protein functions. Models for the coupling of DNA strand exchange to ATP hydrolysis are examined.

    更新日期:2019-11-01
  • Molecular genetics of Mycobacterium tuberculosis pathogenesis.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Josephine E Clark-Curtiss,Shelley E Haydel

    Tuberculosis (TB) has afflicted humankind throughout history. Approximately one third of the world's population is currently infected with Mycobacterium tuberculosis and nearly two million people die of TB annually. Although much has been learned about the structure of the tubercle bacillus, the epidemiology of TB, the physiological and immunological responses of the host to infection, and the physiology of M. tuberculosis in laboratory broth cultures, much of the basic biology of M. tuberculosis in its natural setting (the infected human) remains to be elucidated. Within the past decade, there have been remarkable advances in the development of genetic and molecular biological tools with which to study M. tuberculosis. This review discusses the approaches that have been employed and the progress that has been made in discovering how M. tuberculosis has achieved its prowess as a successful pathogen.

    更新日期:2019-11-01
  • Archeal DNA replication: eukaryal proteins in a bacterial context.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Beatrice Grabowski,Zvi Kelman

    Genome sequences of a number of archaea have revealed an apparent paradox in the phylogenies of the bacteria, archaea, and eukarya, as well as an intriguing set of problems to be resolved in the study of DNA replication. The archaea, long thought to be bacteria, are not only different enough to merit their own domain but also appear to be an interesting mosaic of bacterial, eukaryal, and unique features. Most archaeal proteins participating in DNA replication are more similar in sequence to those found in eukarya than to analogous replication proteins in bacteria. However, archaea have only a subset of the eukaryal replication machinery, apparently needing fewer polypeptides and structurally simpler complexes. The archaeal replication apparatus also contains features not found in other organisms owing, in part, to the broad range of environmental conditions, some extreme, in which members of this domain thrive. In this review the current knowledge of the mechanisms governing DNA replication in archaea is summarized and the similarities and differences of those of bacteria and eukarya are highlighted.

    更新日期:2019-11-01
  • Natural selection and the emergence of a mutation phenotype: an update of the evolutionary synthesis considering mechanisms that affect genome variation.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Lynn Helena Caporale

    Most descriptions of evolution assume that all mutations are completely random with respect to their potential effects on survival. However, much like other phenotypic variations that affect the survival of the descendants, intrinsic variations in the probability, type, and location of genetic change can feel the pressure of natural selection. From site-specific recombination to changes in polymerase fidelity and repair of DNA damage, an organism's gene products affect what genetic changes occur in its genome. Through the action of natural selection on these gene products, potentially favorable mutations can become more probable than random. With examples from variation in bacterial surface proteins to the vertebrate immune response, it is clear that a great deal of genetic change is better than "random" with respect to its potential effect on survival. Indeed, some potentially useful mutations are so probable that they can be viewed as being encoded implicitly in the genome. An updated evolutionary theory includes emergence, under selective pressure, of genomic information that affects the probability of different classes of mutation, with consequences for genome survival.

    更新日期:2019-11-01
  • Multiple sigma subunits and the partitioning of bacterial transcription space.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Tanja M Gruber,Carol A Gross

    Promoter recognition in eubacteria is carried out by the initiation factor sigma, which binds RNA polymerase and initiates transcription. Cells have one housekeeping factor and a variable number of alternative sigma factors that possess different promoter-recognition properties. The cell can choose from its repertoire of sigmas to alter its transcriptional program in response to stress. Recent structural information illuminates the process of initiation and also shows that the two key sigma domains are structurally conserved, even among diverse family members. We use the sigma repertoire of Escherichia coli, Bacillus subtilis, Streptomyces coelicolor, and cyanobacteria to illustrate the different strategies utilized to organize transcriptional space using multiple sigma factors.

    更新日期:2019-11-01
  • Gene organization: selection, selfishness, and serendipity.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Jeffrey G Lawrence

    The apparati behind the replication, transcription, and translation of prokaryotic and eukaryotic genes are quite different. Yet in both classes of organisms, genes may be organized in their respective chromosomes in similar ways by virtue of similarly acting selective forces. In addition, some gene organizations reflect biology unique to each class of organisms. Levels of organization are more complex than those of the simple operon. Multiple transcription units may be organized into larger units, local control regions may act over large chromosomal regions in eukaryotic chromosomes, and cis-acting genes may control the expression of downstream genes in all classes of organisms. All these mechanisms lead to genomes being far more organized, in both prokaryotes and eukaryotes, than hitherto imagined.

    更新日期:2019-11-01
  • Pathways of oxidative damage.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    James A Imlay

    The phenomenon of oxygen toxicity is universal, but only recently have we begun to understand its basis in molecular terms. Redox enzymes are notoriously nonspecific, transferring electrons to any good acceptor with which they make electronic contact. This poses a problem for aerobic organisms, since molecular oxygen is small enough to penetrate all but the most shielded active sites of redox enzymes. Adventitious electron transfers to oxygen create superoxide and hydrogen peroxide, which are partially reduced species that can oxidize biomolecules with which oxygen itself reacts poorly. This review attempts to present our still-incomplete understanding of how reactive oxygen species are formed inside cells and the mechanisms by which they damage specific target molecules. The vulnerability of cells to oxidation lies at the root of obligate anaerobiosis, spontaneous mutagenesis, and the use of oxidative stress as a biological weapon.

    更新日期:2019-11-01
  • The uncultured microbial majority.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Michael S Rappé,Stephen J Giovannoni

    Since the delineation of 12 bacterial phyla by comparative phylogenetic analyses of 16S ribosomal RNA in 1987 knowledge of microbial diversity has expanded dramatically owing to the sequencing of ribosomal RNA genes cloned from environmental DNA. Currently, only 26 of the approximately 52 identifiable major lineages, or phyla, within the domain Bacteria have cultivated representatives. Evidence from field studies indicates that many of the uncultivated phyla are found in diverse habitats, and some are extraordinarily abundant. In some important environments, including seawater, freshwater, and soil, many biologically and geochemically important organisms are at best only remotely related to any strain that has been characterized by phenotype or by genome sequencing. Genome sequence information that would allow ribosomal RNA gene trees to be related to broader patterns in microbial genome evolution is scant, and therefore microbial diversity remains largely unexplored territory.

    更新日期:2019-11-01
  • Measles virus 1998-2002: progress and controversy.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Glenn F Rall

    Despite the extensive media exposure that viruses such as West Nile, Norwalk, and Ebola have received lately, and the emerging threat that old pathogens may reappear as new agents of terrorism, measles virus (MV) persists as one of the leading causes of death by infectious agents worldwide, approaching the annual mortality rate of human immunodeficiency virus (HIV)-1. For most MV victims, fatality is indirect: Virus-induced transient immunosuppression predisposes the individual to opportunistic infections that, left untreated, can result in mortality. In rare cases, MV may also cause progressive neurodegenerative disease. During the past five years (1998-2002), development of animal models and the application of reverse genetics and immunological assays have collectively contributed to major progress in our understanding of MV biology and pathogenesis. Nevertheless, questions and controversies remain that are the basis for future research. In this review, major advances and current debates are discussed, including MV receptor usage, the cellular basis of immunosuppression, the suspected role of MV in "nonviral" diseases such as multiple sclerosis and Paget's disease, and the controversy surrounding MV vaccine safety.

    更新日期:2019-11-01
  • Vaccinia virus motility.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Geoffrey L Smith,Brendan J Murphy,Mansun Law

    Vaccinia virus (VV), the virus smallpox vaccine, replicates in the cytoplasm of infected cells. The intracellular movement of this large virus would be inefficient without specific transport mechanisms; therefore, VV uses microtubules for movement during both entry and egress. In addition, the dissemination of virus from infected cells to adjacent cells is promoted by the polymerization of actin beneath cell surface virions to drive virus particles away from the cell. Last, the roles of different VV particles in virus movement within and between hosts are discussed.

    更新日期:2019-11-01
  • Bacteriophage-induced modifications of host RNA polymerase.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Sergei Nechaev,Konstantin Severinov

    Bacteriophages have developed an impressive array of ingenious mechanisms to modify bacterial host RNA polymerase to make it serve viral needs. In this review we summarize the current knowledge about two types of host RNA polymerase modifications induced by double-stranded DNA phages: covalent modifications and modifications through RNA polymerase-binding proteins. We interpret the biochemical and genetic data within the framework of a structure-function model of bacterial RNA polymerase and viral biology.

    更新日期:2019-11-01
  • Transposable elements in filamentous fungi.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Marie-Josée Daboussi,Pierre Capy

    The past 10 years have been productive in the characterization of fungal transposable elements (TEs). All eukaryotic TEs described are found including an extraordinary prevalence of active members of the pogo family. The role of TEs in mutation and genome organization is well documented, leading to significant advances in our perception of the mechanisms underlying genetic changes in these organisms. TE-mediated changes, associated with transposition and recombination, provide a broad range of genetic variation, which is useful for natural populations in their adaptation to environmental constraints, especially for those lacking the sexual stage. Interestingly, some fungal species have evolved distinct silencing mechanisms that are regarded as host defense systems against TEs. The examination of forces acting on the evolutionary dynamics of TEs should provide important insights into the interactions between TEs and the fungal genome. Another issue of major significance is the practical applications of TEs in gene tagging and population analysis, which will undoubtedly facilitate research in systematic biology and functional genomics.

    更新日期:2019-11-01
  • Bacterial motility on a surface: many ways to a common goal.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Rasika M Harshey

    When free-living bacteria colonize biotic or abiotic surfaces, the resultant changes in physiology and morphology have important consequences on their growth, development, and survival. Surface motility, biofilm formation, fruiting body development, and host invasion are some of the manifestations of functional responses to surface colonization. Bacteria may sense the growth surface either directly through physical contact or indirectly by sensing the proximity of fellow bacteria. Extracellular signals that elicit new gene expression include autoinducers, amino acids, peptides, proteins, and carbohydrates. This review focuses mainly on surface motility and makes comparisons to features shared by other surface phenomenon.

    更新日期:2019-11-01
  • Spatial and temporal control of differentiation and cell cycle progression in Caulobacter crescentus.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Nora Ausmees,Christine Jacobs-Wagner

    The dimorphic and intrinsically asymmetric bacterium Caulobacter crescentus has become an important model organism to study the bacterial cell cycle, cell polarity, and polar differentiation. A multifaceted regulatory network orchestrates the precise coordination between the development of polar organelles and the cell cycle. One master response regulator, CtrA, directly controls the initiation of chromosome replication as well as several aspects of polar morphogenesis and cell division. CtrA activity is temporally and spatially regulated by multiple partially redundant control mechanisms, such as transcription, phosphorylation, and targeted proteolysis. A multicomponent signal transduction network upstream CtrA, containing histidine kinases CckA, PleC, DivJ, and DivL and the essential response regulator DivK, contributes to the control of CtrA activity in response to cell cycle and developmental cues. An intriguing feature of this signaling network is the dynamic cell cycle-dependent polar localization of its components, which is believed to have a novel regulatory function.

    更新日期:2019-11-01
  • Assembly dynamics of the bacterial cell division protein FTSZ: poised at the edge of stability.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Laura Romberg,Petra Anne Levin

    FtsZ is a prokaryotic tubulin homolog that assembles into a ring at the future site of cell division. The resulting "Z ring" forms the framework for the division apparatus, and its assembly is regulated throughout the bacterial cell cycle. A highly dynamic structure, the Z ring exhibits continual subunit turnover and the ability to rapidly assemble, disassemble, and, under certain circumstances, relocalize. These in vivo properties are ultimately due to FtsZ's capacity for guanosine triphosphate (GTP)-dependent, reversible polymerization. FtsZ polymer stability appears to be fine-tuned such that subtle changes in its assembly kinetics result in large changes in the Z ring structure. Thus, regulatory proteins that modulate FtsZ's assembly dynamics can cause the ring to rapidly remodel in response to developmental and environmental cues.

    更新日期:2019-11-01
  • Bacterial membrane lipids: where do we stand?
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    John E Cronan

    Phospholipids play multiple roles in bacterial cells. These are the establishment of the permeability barrier, provision of the environment for many enzyme and transporter proteins, and they influence membrane-related processes such as protein export and DNA replication. The lipid synthetic pathway also provides precursors for protein modification and for the synthesis of other molecules. This review concentrates on the phospholipid synthetic pathway and discusses recent data on the synthesis and function of phospholipids mainly in the bacterium Escherichia coli.

    更新日期:2019-11-01
  • On the trail of a cereal killer: Exploring the biology of Magnaporthe grisea.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Nicholas J Talbot

    The blast fungus Magnaporthe grisea causes a serious disease on a wide variety of grasses including rice, wheat, and barley. Rice blast is the most serious disease of cultivated rice and therefore poses a threat to the world's most important food security crop. Here, I review recent progress toward understanding the molecular biology of plant infection by M. grisea, which involves development of a specialized cell, the appressorium. This dome-shaped cell generates enormous turgor pressure and physical force, allowing the fungus to breach the host cuticle and invade plant tissue. The review also considers the role of avirulence genes in M. grisea and the mechanisms by which resistant rice cultivars are able to perceive the fungus and defend themselves. Finally, the likely mechanisms that promote genetic diversity in M. grisea and our current understanding of the population structure of the blast fungus are evaluated.

    更新日期:2019-11-01
  • Molecular pathogenicity of the oral opportunistic pathogen Actinobacillus actinomycetemcomitans.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Brian Henderson,Sean P Nair,John M Ward,Michael Wilson

    Periodontitis is mankind's most common chronic inflammatory disease. One severe form of periodontitis is localized aggressive periodontitis (LAP), a condition to which individuals of African origin demonstrate an increased susceptibility. The main causative organism of this disease is Actinobacillus actinomycetemcomitans. A member of the Pasteurellaceae, A. actinomycetemcomitans produces a number of interesting putative virulence factors including (a) an RTX leukotoxin that targets only neutrophils and monocytes and whose action is influenced by a novel type IV secretion system involved in bacterial adhesion; (b) the newly discovered toxin, cytolethal distending toxin (CDT); and (c) a secreted chaperonin 60 with potent leukocyte-activating and bone resorbing activities. This organism also produces a plethora of proteins able to inhibit eukaryotic cell cycle progression and proteins and peptides that can induce distinct forms of proinflammatory cytokine networks. A range of other proteins interacting with the host is currently being uncovered. In addition to these secreted factors, A. actinomycetemcomitans is invasive with an unusual mechanism for entering, and traveling within, eukaryotic cells. This review focuses on recent advances in our understanding of the molecular and cellular pathogenicity of this fascinating oral bacterium.

    更新日期:2019-11-01
  • Gathering no moss.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 2003-10-07
    Julian Davies

    I never imagined that I would be asked to write an autobiography in a microbiology tome. For that matter, little did I think that I would consider microbiology the most intriguing subject in the life sciences and the only field I wanted to study. My formal scientific training was in chemistry. This is a recounting of my conversion and the opportunities I have had to work in the microbial sciences with some of the major figures (and characters) during a period of marvelous intensity and productivity. I want to recognize and thank my many distinguished colleagues for the ways in which they have helped me to experience a fruitful and stimulating life as a microbiologist.

    更新日期:2019-11-01
  • GENETIC ASPECTS OF METABOLIC CONTROL.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1964-01-01
    W K MAAS,E MCFALL

    更新日期:2019-11-01
  • THE GENETICS OF ANIMAL VIRUSES.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1964-01-01
    F FENNER,J F SAMBROOK

    更新日期:2019-11-01
  • BIOCHEMICAL MECHANISMS OF DRUG RESISTANCE.
    Annu. Rev. Microbiol. (IF 10.242) Pub Date : 1964-01-01
    H S MOYED

    更新日期:2019-11-01
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