Bacterial cytokinesis is mediated by the Z-ring, which is formed by the prokaryotic tubulin homolog FtsZ. Recent data indicate that the Z-ring is composed of small patches of FtsZ protofilaments that travel around the bacterial cell by treadmilling. Treadmilling involves a switch from a relaxed (R) state, favored for monomers, to a tense (T) conformation, which is favored upon association into filaments

FtsZ, a tubulin-like GTPase, is essential for bacterial cell division. In the presence of GTP, FtsZ polymerizes into filamentous structures, which are key to generating force in cell division. However, the structural basis for the molecular mechanism underlying FtsZ function remains to be elucidated. In this study, crystal structures of the enzymatic domains of FtsZ from Klebsiella pneumoniae (KpFtsZ)

Calpain is a Ca2+-activated, heterodimeric cysteine protease consisting of a large catalytic subunit and a small regulatory subunit. Dysregulation of this enzyme is involved in a range of pathological conditions such as cancer, Alzheimer's disease and rheumatoid arthritis, and thus calpain I is a drug target with potential therapeutic applications. Difficulty in the production of this enzyme has hindered

Cytisine, a natural product with high affinity for clinically relevant nicotinic acetylcholine receptors (nAChRs), is used as a smoking-cessation agent. The compound displays an excellent clinical profile and hence there is an interest in derivatives that may be further improved or find use in the treatment of other conditions. Here, the binding of a cytisine derivative modified by the addition of

Serine racemase (SR) is a pyridoxal 5'-phosphate (PLP)-containing enzyme that converts L-serine to D-serine, an endogenous co-agonist for the N-methyl-D-aspartate receptor (NMDAR) subtype of glutamate ion channels. SR regulates D-serine levels by the reversible racemization of L-serine to D-serine, as well as the catabolism of serine by α,β-elimination to produce pyruvate. The modulation of SR activity

Adeno-associated viruses (AAVs) are used as in vivo gene-delivery vectors in gene-therapy products and have been heavily investigated for numerous indications. Over 100 naturally occurring AAV serotypes and variants have been isolated from primate samples. Many reports have described unique properties of these variants (for instance, differences in potency, target cell or evasion of the immune response)

The structure of the MP-4 protein was previously determined at a resolution of 2.8 Å. Owing to the unavailability of gene-sequence information at the time, the side-chain assignment was carried out on the basis of a partial sequence available through Edman degradation, sequence homology to orthologs and electron density. The structure of MP-4 has now been determined at a higher resolution (2.22 Å)

RcnR is a transcription factor that regulates the homeostasis of cobalt and nickel in bacterial cells. Escherichia coli RcnR was crystallized with DNA that encompasses the DNA-binding site. X-ray diffraction data were collected to 2.9 Å resolution. The crystal belonged to space group P6122 or P6522, with unit-cell parameters a = b = 73.59, c = 157.66 Å, α = β = 90, γ = 120°.

This study presents the crystal structure of a thiol variant of the human mitochondrial branched-chain aminotransferase protein. Human branched-chain aminotransferase (hBCAT) catalyzes the transamination of the branched-chain amino acids leucine, valine and isoleucine and α-ketoglutarate to their respective α-keto acids and glutamate. hBCAT activity is regulated by a CXXC center located approximately

Direct soaking of protein crystals with small-molecule fragments grouped into complementary clusters is a useful technique when assessing the potential of a new crystal system to support structure-guided drug discovery. It provides a robustness check prior to any extensive crystal screening, a double check for assay binding cutoffs and structural data for binding pockets that may or may not be picked

The Escherichia coli rnlAB operon encodes a toxin-antitoxin module that is involved in protection against infection by bacteriophage T4. The full-length RnlA-RnlB toxin-antitoxin complex as well as the toxin RnlA were purified to homogeneity and crystallized. When the affinity tag is placed on RnlA, RnlB is largely lost during purification and the resulting crystals exclusively comprise RnlA. A homogeneous

Eisenia hydrolysis-enhancing protein (EHEP), which is a novel protein that has been identified in Aplysia kurodai, protects β-glucosidases from phlorotannin inhibition to facilitate the production of glucose from the laminarin abundant in brown algae. Hence, EHEP has attracted attention for its potential applications in producing biofuel from brown algae. In this study, EHEP was purified from the natural

PitA is the putative tip adhesin of the pilus islet 2 (PI-2)-encoded sortase-dependent pilus in the Gram-positive Streptococcus oralis, an opportunistic pathogen that often flourishes within the diseased human oral cavity. Early colonization by S. oralis and its interaction with Actinomyces oris seeds the development of oral biofilm or dental plaque. Here, the PI-2 pilus plays a vital role in mediating

Mitochondrial E3 ubiquitin ligase 1 (MUL1) is located in the mitochondrial outer membrane and regulates various biological processes, including apoptosis, cell growth, mitophagy and mitochondrial dynamics. The C-terminal region of MUL1 faces the cytoplasm and contains the RING domain (MUL1-RING) where the Ub~E2 thioester binds. Unlike most RING-type E3 enzymes, MUL1-RING alone does not have an additional

A high-affinity anti-cocaine monoclonal antibody, designated h2E2, is entering phase 1 clinical trials for cocaine abuse therapy. To gain insight into the molecular details of its structure that are important for binding cocaine and cocaine metabolites, the Fab fragment was generated and crystallized with and without ligand. Structures of the unliganded Fab and the Fab fragment bound to benzoylecgonine

The Gram-positive bacterium Streptococcus pneumoniae, a major human pathogen, is a regular colonizer of the upper and lower respiratory tracts. Pneumococcal adherence and virulence factor A (PavA), a fibronectin-binding bacterial protein, from S. pneumoniae is an important facilitator of its colonization of host cells. In this study, the crystal structure of the N-terminal domain of PavA (SpPavA-N)

The structure of a 22-base-pair RNA helix with mismatched pyrimidine base pairs is reported. The helix contains two symmetry-related CUG sequences: a triplet-repeat motif implicated in myotonic dystrophy type 1. The CUG repeat contains a U-U mismatch sandwiched between Watson-Crick pairs. Additionally, the center of the helix contains a dimerized UUCG motif with tandem pyrimidine (U-C/C-U) mismatches

Acyl carrier proteins (ACPs) are important components in fatty-acid biosynthesis in prokaryotes. Rv0100 is predicted to be an essential ACP in Mycobacterium tuberculosis, the pathogen that is the causative agent of tuberculosis, and therefore has the potential to be a novel antituberculosis drug target. Here, the successful cloning and purification of Rv0100 using Mycobacterium smegmatis as a host

Bovine β-lactoglobulin was crystallized from 3 M NaCl buffered at pH 3.8 with sodium citrate as thick hexagonal prisms of greater than 1 mm in edge length. Analyses of the X-ray diffraction intensities using three different current algorithms were unanimous in specifying the space group to be P6322, with unit-cell dimensions a = b = 75.47, c = 140.79 Å. No progress could be made, however, towards an

An increased level of granulocyte-macrophage colony-stimulating factor has a potential role in the development of autoimmune diseases, and the neutralization of its activity by monoclonal antibodies is a promising therapy for some diseases. Here, the crystal structure of the Fab region of EV1007, a fully human antibody expressed in Chinese hamster ovary cells that was developed from human peripheral

Prolyl aminodipeptidase (PepX) is an enzyme that hydrolyzes peptide bonds from the N-terminus of substrates when the penultimate amino-acid residue is a proline. Prolyl peptidases are of particular interest owing to their ability to hydrolyze food allergens that contain a high percentage of proline residues. PepX from Lactobacillus helveticus was cloned and expressed in Escherichia coli as an N-terminally

Archaea are motile by the rotation of the archaellum. The archaellum switches between clockwise and counterclockwise rotation, and movement along a chemical gradient is possible by modulation of the switching frequency. This modulation involves the response regulator CheY and the archaellum adaptor protein CheF. In this study, two new crystal forms and protein structures of CheY are reported. In both

A putative open reading frame encoding GTP cyclohydrolase I from Listeria monocytogenes was expressed in a recombinant Escherichia coli strain. The recombinant protein was purified and was confirmed to convert GTP to dihydroneopterin triphosphate (Km = 53 µM; vmax = 180 nmol mg-1 min-1). The protein was crystallized from 1.3 M sodium citrate pH 7.3 and the crystal structure was solved at a resolution

The crystallization of amidase, the ultimate enzyme in the Trp-dependent auxin-biosynthesis pathway, from Arabidopsis thaliana was attempted using protein samples with at least 95% purity. Cube-shaped crystals that were assumed to be amidase crystals that belonged to space group I4 (unit-cell parameters a = b = 128.6, c = 249.7 Å) were obtained and diffracted to 3.0 Å resolution. Molecular replacement

Yersinia pestis, the causative agent of bubonic plague, is one of the most lethal pathogens in recorded human history. Today, the concern is the possible misuse of Y. pestis as an agent in bioweapons and bioterrorism. Current therapies for the treatment of plague include the use of a small number of antibiotics, but clinical cases of antibiotic resistance have been reported in some areas of the world

Hygromycin B (HygB) is one of the aminoglycoside antibiotics, and it is widely used as a reagent in molecular-biology experiments. Two kinases are known to inactivate HygB through phosphorylation: aminoglycoside 7''-phosphotransferase-Ia [APH(7'')-Ia] from Streptomyces hygroscopicus and aminoglycoside 4-phosphotransferase-Ia [APH(4)-Ia] from Escherichia coli. They phosphorylate the hydroxyl groups

Stimulator of interferon genes (STING) binds cyclic dinucleotides (CDNs), which induce a large conformational change of the protein. The structural basis of activation of STING by CDNs is rather well understood. Unliganded STING forms an open dimer that undergoes a large conformational change (∼10 Å) to a closed conformation upon the binding of a CDN molecule. This event activates downstream effectors

Moenomycin-type antibiotics are phosphoglycolipids that are notable for their unique modes of action and have proven to be useful in animal nutrition. The gene clusters tchm from Actinoplanes teichomyceticus and moe from Streptomyces are among a limited number of known moenomycin-biosynthetic pathways. Most genes in tchm have counterparts in the moe cluster, except for tchmy and tchmz, the functions

Described here are instructions for building and using an inexpensive automated microscope (AMi) that has been specifically designed for viewing and imaging the contents of multi-well plates. The X, Y, Z translation stage is controlled through dedicated software (AMiGUI) that is being made freely available. Movements are controlled by an Arduino-based board running grbl, and the graphical user interface

Endoplasmic reticulum (ER)-associated degradation (ERAD) is a protein quality-control pathway in eukaryotes in which misfolded ER proteins are polyubiquitylated, extracted and ultimately degraded by the proteasome. This process involves ER membrane-embedded ubiquitin E2 and E3 enzymes, as well as a soluble E2 enzyme (Ubc7 in Saccharomyces cerevisiae and UBE2G2 in mammals). E2-binding regions (E2BRs)

Turn-on aptamers are in vitro-selected RNAs that bind to conditionally fluorescent small molecules and enhance their fluorescence. Upon binding TO1-biotin, the iMango-III aptamer achieves the largest fluorescence enhancement reported for turn-on aptamers (over 5000-fold). This aptamer was generated by structure-guided engineering and functional reselection of the parental aptamer Mango-III. Structures

The stringent response, controlled by (p)ppGpp, enables bacteria to trigger a strong phenotypic resetting that is crucial to cope with adverse environmental changes and is required for stress survival and virulence. In the bacterial cell, (p)ppGpp levels are regulated by the concerted opposing activities of RSH (RelA/SpoT homologue) enzymes that can transfer a pyrophosphate group of ATP to the 3' position

The crystal structure of haemoglobin from Atlantic cod has been solved to 2.54 Å resolution. The structure consists of two tetramers in the crystallographic asymmetric unit. The structure of haemoglobin obtained from one individual cod suggests polymorphism in the tetrameric assembly.

Kallikrein 4 (KLK4) is a serine protease that is predominantly expressed in the prostate and is overexpressed in prostate cancer. As such, it has gained attention as an attractive target for prostate cancer therapeutics. Currently, only liganded structures of KLK4 exist in the Protein Data Bank. Until now, inferences about the subtle structural changes in KLK4 upon ligand binding have been made by

Successful pathogenesis is a cumulative effect of the virulence factors of a pathogen and its capability to efficiently utilize the available nutrients from the host. Streptococcus pneumoniae, a Gram-positive opportunistic pathogen, may either reside asymptomatically as a nasopharyngeal commensal inside the human host or cause lethal diseases, including pneumonia, meningitis and sepsis. S. pneumoniae

Protein kinase CK2a1 is a serine/threonine kinase that plays a crucial role in the growth, proliferation and survival of cells and is a well known target for tumour and glomerulonephritis therapies. Here, the crystal structure of the kinase domain of CK2a1 complexed with 5-iodotubercidin (5IOD), an ATP-mimetic inhibitor, was determined at 1.78 Å resolution. The structure shows distinct structural features

The crystal structure is reported of p-hydroxybenzoate hydroxylase (PobA) from Pseudomonas putida, a possible drug target to combat tetracycline resistance, in complex with flavin adenine dinucleotide (FAD). The structure was refined at 2.2 Å resolution with four polypeptide chains in the asymmetric unit. Based on the results of pairwise structure alignments, PobA from P. putida is structurally very

Riboswitches are conformationally dynamic RNAs that regulate gene expression by binding specific small molecules. ZTP riboswitches bind the purine-biosynthetic intermediate 5-aminoimidazole-4-carboxamide riboside 5'-monophosphate (ZMP) and its triphosphorylated form (ZTP). Ligand binding to this riboswitch ultimately upregulates genes involved in folate and purine metabolism. Using an X-ray free-electron

Biofilms are microbial communities that are embedded in the extracellular matrix. The exopolysaccharide (EPS) is a key component of the biofilm matrix that maintains the structure of the biofilm and protects the bacteria from antimicrobials. Microbial glycoside hydrolases have been exploited to disrupt biofilms by breaking down EPSs. PssZ has recently been identified as a glycoside hydrolase that can

The phylogenetically divergent spirochete bacterium Treponema pallidum subsp. pallidum is the causative agent of syphilis. Central to the capacity of T. pallidum to establish infection is the ability of the pathogen to attach to a diversity of host cells. Many pathogenic bacteria employ leucine-rich repeat (LRR) domain-containing proteins to mediate protein-protein interactions, including attachment

The iron superoxide dismutase found in the pathogenic amoeba Acanthamoeba castellanii (AcFeSOD) may play essential roles in the survival of the parasite, not only by protecting it from endogenous oxidative stress but also by detoxifying oxidative killing of the parasite by host immune effector cells. The AcFeSOD protein was expressed in a stable form using an Escherichia coli expression system and

(S)-3-O-Geranylgeranylglyceryl phosphate synthase (GGGPS) catalyzes the initial ether-bond formation between sn-glycerol 1-phosphate (G1P) and geranylgeranyl pyrophosphate to synthesize (S)-3-O-geranylgeranylglyceryl phosphate in the production of an archaeal cell-membrane lipid molecule. Archaeal GGGPS proteins are divided into two groups (group I and group II). In this study, the crystal structure

Human liver pyruvate kinase (hLPYK) converts phosphoenolpyruvate to pyruvate in the final step of glycolysis. hLPYK is allosterically activated by fructose-1,6-bisphosphate (Fru-1,6-BP). The allosteric site, as defined by previous structural studies, is located in domain C between the phosphate-binding loop (residues 444-449) and the allosteric loop (residues 527-533). In this study, the X-ray crystal

Interferon-inducible protein 204 (p204) binds to microbial DNA to elicit inflammatory responses and induce interferon production. p204 also modulates cell proliferation and differentiation by regulating various transcription factors. The C-terminal HIN domains in p204 are believed to be responsible for DNA binding, but the binding mode is not fully understood. The DNA-binding affinity of the p204 HIN1

The thymidylate synthases ThyA and Thy1 are enzymes that catalyse the formation of thymidine monophosphate from 2'-deoxyuridine monophosphate. Thy1 (or ThyX) requires flavin for catalytic reactions, while ThyA does not. In the present study, the crystal structure of the flavin-dependent thymidylate synthase Thy1 from Thermus thermophilus HB8 (TtThy1, TTHA1096) was determined in complex with FAD and

The mechanism by which potassium ions are transported through ion channels is currently being investigated by several groups using many different techniques. Clarification of the location of water molecules during transport is central to understanding how these integral membrane proteins function. Neutrons have a unique sensitivity to both hydrogen and potassium, rendering neutron crystallography capable

Splicing factor proline/glutamine-rich (SFPQ) is an essential RNA-binding protein that is implicated in many aspects of nuclear function. The structures of SFPQ and two paralogs, non-POU domain-containing octamer-binding protein and paraspeckle component 1, from the Drosophila behavior human splicing protein family have previously been characterized. The unusual arrangement of the four domains, two

Aerobic thermoacidophilic archaea belonging to the genus Sulfolobus harbor peroxiredoxins, thiol-dependent peroxidases that assist in protecting the cells from oxidative damage. Here, the crystal structure of the 1-Cys peroxiredoxin from Sulfolobus islandicus, named 1-Cys SiPrx, is presented. A 2.75 Å resolution data set was collected from a crystal belonging to space group P212121, with unit-cell

Chagas disease, which is caused by Trypanosoma cruzi, affects more than six million people worldwide. Cruzain is the major cysteine protease involved in the survival of this parasite. Here, the expression, purification and crystallization of this enzyme are reported. The cruzain crystals diffracted to 1.2 Å resolution, yielding two novel cruzain structures: apocruzain and cruzain bound to the reversible

Neutral endopeptidase (neprilysin; NEP) is a proteinase that cleaves a wide variety of peptides and has been implicated in Alzheimer's disease, cardiovascular conditions, arthritis and other inflammatory diseases. The structure of the soluble extracellular domain (residues 55-750) of rabbit neprilysin was solved both in its native form at 2.1 Å resolution, and bound to the inhibitors phosphoramidon

The SPRY domain-containing SOCS box protein 2 (SPSB2) is one of four mammalian SPSB proteins that are characterized by a C-terminal SOCS box and a central SPRY/B30.2 domain. SPSB2 interacts with inducible nitric oxide synthase (iNOS) via the SPRY domain and polyubiquitinates iNOS, resulting in its proteasomal degradation. Inhibitors that can disrupt SPSB2-iNOS interaction and augment NO production

β-1,4-Galactanases are glycoside hydrolases that are involved in the degradation of pectin and belong to family 53 in the classification of glycoside hydrolases. Previous studies have elucidated the structures of several fungal and two bacterial galactanases, while biochemical studies have indicated differences in the product profiles of different members of the family. Structural studies of ligand