Arabidopsis VRN genes mediate vernalization, the process by which a long period of cold induces mitotically stable state that leads to accelerated flowering during later development. VRN1 encodes protein binds DNA in vitro non–sequence-specific manner and functions repression major target vernalization pathway, floral repressor FLC . Overexpression reveals vernalization-independent function for , mediated predominantly through pathway integrator FT demonstrates requires vernalization-specific factors

Vernalization is the acceleration of flowering by prolonged cold that aligns onset reproductive development with spring conditions. A key step vernalization in Arabidopsis epigenetic silencing FLOWERING LOCUS C ( FLC ), which encodes a repressor flowering. The vernalization-induced associated histone deacetylation and H3K27me2 H3K9me2 methylation mediated VRN/VIN proteins. We have analyzed whether different methyltransferases chromodomain protein LIKE HETEROCHROMATIN PROTEIN (LHP)1 might...

Abstract Carbohydrate recognition is essential for growth, cell adhesion and signalling in all living organisms. A highly conserved carbohydrate binding module, LysM, found proteins from viruses, bacteria, fungi, plants mammals. LysM modules recognize polysaccharides containing N -acetylglucosamine (GlcNAc) residues including peptidoglycan, an component of the bacterial wall. However, molecular mechanism underpinning LysM–peptidoglycan interactions remains unclear. Here we describe basis...

The present study demonstrates the antibacterial potential of a phage endolysin against Gram-negative pathogens, particularly multidrug resistant strains Acinetobacter baumannii. We have cloned, heterologously expressed and characterized novel (ABgp46) from vb_AbaP_CEB1 tested its activity several multidrug-resistant A. baumannii strains. LC-MS revealed that ABgp46 is an N-acetylmuramidase, also active over broad pH range (4.0-10.0) temperatures up to 50°C. Interestingly, has intrinsic...

Summary Cell morphology and viability in Eubacteria is dictated by the architecture of peptidoglycan, major essential structural component cell wall. Although biochemical composition peptidoglycan well understood, how can accommodate dynamics growth division while maintaining shape remains largely unknown. Here, we elucidate bacteria with ovoid (ovococci), which includes a number important pathogens, combining analyses atomic force super‐resolution microscopies. Atomic microscopy analysis...

Abstract Biopolymer composite cell walls maintain shape and resist forces in plants, fungi bacteria. Peptidoglycan, a crucial antibiotic target immunomodulator, performs this role The textbook structural model of peptidoglycan is highly ordered, crystalline material. Here we use atomic force microscopy (AFM) to image individual glycan chains from Escherichia coli unprecedented detail. We quantify map the extent which are oriented similar direction (orientational order), showing it much less...

ABSTRACT Most bacterial cells are enclosed in a single macromolecule of the cell wall polymer, peptidoglycan, which is required for shape determination and maintenance viability, while peptidoglycan biosynthesis an important antibiotic target. It hypothesized that cellular enlargement requires regional expansion through coordinated insertion hydrolysis peptidoglycan. Here, group (apparent glucosaminidase) hydrolases identified together correct morphology Staphylococcus aureus , demonstrating...

The bacterial cell wall is essential for viability, but despite its ability to withstand internal turgor must remain dynamic permit growth and division. Peptidoglycan the major structural polymer, whose synthesis requires multiple interacting components. human pathogen Staphylococcus aureus a prolate spheroid that divides in three orthogonal planes. Here, we have integrated cellular morphology during division with molecular level resolution imaging of peptidoglycan components responsible....

Abstract Staphylococcus aureus frequently causes infections that are challenging to treat, leading high rates of persistent and relapsing infection. Here, understand how the host environment influences treatment outcomes, we study impact human serum on staphylococcal antibiotic susceptibility. We show triggers a degree tolerance lipopeptide daptomycin several other classes antibiotic. Serum-induced is due two independent mechanisms. Firstly, defence peptide LL-37 induces by triggering GraRS...

Summary Bacillus anthracis , the aetiological agent of anthrax, is a Gram‐positive spore‐forming bacterium. The cell wall vegetative cells B. surrounded by an S‐layer. An array remained when sap gene described as encoding S‐layer component, was deleted. remaining termed EA1, chromosomally encoded. EA1 (eag) obtained on two overlapping fragments in Escherichia coli and shown to be contiguous gene. amino acid sequence, deduced from eag nucleotide shows classical protein features (no cysteine,...

Lysozyme is a key component of the innate immune response in humans that provides first line defense against microbes. The bactericidal effect lysozyme relies both on cell wall lytic activity this enzyme and cationic antimicrobial peptide leads to membrane permeabilization. Among Gram-positive bacteria, opportunistic pathogen Enterococcus faecalis has been shown be extremely resistant lysozyme. This unusual resistance explained partly by peptidoglycan O-acetylation, which inhibits enzymatic...

The Gram-positive opportunistic pathogen Enterococcus faecalis is frequently responsible for nosocomial infections in humans and represents one of the most common bacteria isolated from recalcitrant endodontic (root canal) infections. E. intrinsically resistant to several antibiotics routinely used clinical settings (such as cephalosporins aminoglycosides) can acquire resistance vancomycin (vancomycin-resistant enterococci).

Enterococci are opportunistic pathogens responsible for hospital- and community-acquired infections. All enterococci produce a surface polysaccharide called EPA ( e nterococcal p olysaccharide ntigen) required biofilm formation, antibiotic resistance, pathogenesis. Despite the critical role of in cell growth division as major virulence factor, no information is available on its structure. Here, we report complete structure polymer produced by model strain E. faecalis V583. We describe...

Type VI secretion systems (T6SSs) are nanomachines used by bacteria to inject toxic effectors into competitors. The identity and mechanism of many remain unknown. We characterized a Salmonella T6SS antibacterial effector called Tlde1 that is in target-cell periplasm neutralized its cognate immunity protein (Tldi1). Microscopy analysis reveals cells expressing stop dividing lose cell envelope integrity. Bioinformatic uncovers similarities between the catalytic domain l,d-transpeptidases....

ABSTRACT Bacillus anthracis , the etiological agent of anthrax, is a gram-positive spore-forming bacterium. Fully virulent bacilli are toxinogenic and capsulated. Two abundant surface proteins, including major antigen, components B. layer (S-layer). The paracrystalline S-layer has previously only been found in noncapsulated vegetative cells. Here we report that proteins also synthesized under conditions where poly-γ- d -glutamic acid capsule present. Structural immunological analyses show...

Many surface proteins of Gram‐positive bacteria contain motifs, about 50 amino acids long, called S‐layer homology (SLH) motifs. Bacillus anthracis , the causal agent anthrax, synthesizes two proteins, each with three SLH motifs towards amino‐terminus. We used biochemical and genetic approaches to investigate involvement these in cell anchoring. Proteinase K digestion produced polypeptides lacking stable three‐motif were Escherichia coli that able bind B. walls vitro demonstrating organized...

Summary Adjustment of the synthesis abundant protein to requirements cell involves processes critical minimization energy expenditure. The regulation S‐layer genes might be a good model for such because expression must controlled, that encoded proteins exactly cover surface bacterium. Bacillus anthracis has two genes, sap and eag , encoding Sap EA1 respectively. We report production localization are under developmental control, suggesting an exponential phase ‘Sap layer’ is subsequently...

The major peptidoglycan hydrolase of Enterococcus faecalis, AtlA, has been identified, but its enzyme activity remains unknown. We have used tandem mass spectrometry analysis hydrolysis products obtained using the purified protein to show that AtlA is an N-acetylglucosaminidase. To gain insight into regulation activity, three domains were alone or in combination following expression truncated forms atlA gene Escherichia coli partial digestion by proteinase K. central domain was catalytically...

Identification of the full complement peptidoglycan hydrolases detected by zymogram in Enterococcus faecalis extracts led to characterization two novel that we named AtlB and AtlC. Both enzymes have a similar modular organization comprising central catalytic domain fused LysM peptidoglycan-binding modules. AtlC displayed N-acetylmuramidase activity, as demonstrated tandem mass spectrometry analyses fragments generated purified enzymes. The genes encoding were deleted either alone or...

Summary Gram‐positive surface proteins can be covalently or non‐covalently anchored to the cell wall and impart important properties on bacterium in respect of envelope organisation interaction with environment. We describe here a mechanism protein anchoring involving tandem CWB 2 motifs found large number Firmicutes. In Clostridium difficile family, we show three repeats CWB2 motif are essential for correct wall. non‐identical cannot substitute each other, as shown by secretion into culture...

Bacteriophage-encoded endolysins are highly diverse enzymes that cleave the bacterial peptidoglycan layer. Current research focuses on their potential applications in medicine, food conservation, and as biotechnological tools. Despite wealth of relying use endolysin, little is known about enzymatic properties these enzymes, especially case bacteriophages infecting Gram-negative species. Automated genome annotations therefore remain to be confirmed. Here, we report biochemical analysis...