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Peptidoglycan Biosynthesis (peptidoglycan + biosynthesis)
Selected AbstractsEvolution of peptidoglycan biosynthesis under the selective pressure of antibiotics in Gram-positive bacteriaFEMS MICROBIOLOGY REVIEWS, Issue 2 2008Jean-Luc Mainardi Abstract Acquisition of resistance to the two classes of antibiotics therapeutically used against Gram-positive bacteria, the glycopeptides and the ,-lactams, has revealed an unexpected flexibility in the peptidoglycan assembly pathway. Glycopeptides select for diversification of the fifth position of stem pentapeptides because replacement of d -Ala by d -lactate or d -Ser at this position prevents binding of the drugs to peptidoglycan precursors. The substitution is generally well tolerated by the classical d,d -transpeptidases belonging to the penicillin-binding protein family, except by low-affinity enzymes. Total elimination of the fifth residue by a d,d -carboxypeptidase requires a novel cross-linking enzyme able to process the resulting tetrapeptide stems. This enzyme, an l,d -transpeptidase, confers cross-resistance to ,-lactams and glycopeptides. Diversification of the side chain of the precursors, presumably in response to the selective pressure of peptidoglycan endopeptidases, is controlled by aminoacyl transferases of the Fem family that redirect specific aminoacyl-tRNAs from translation to peptidoglycan synthesis. Diversification of the side chains has been accompanied by a parallel divergent evolution of the substrate specificity of the l,d -transpeptidases, in contrast to the d,d -transpeptidases, which display an unexpected broad specificity. This review focuses on the role of antibiotics in selecting or counter-selecting diversification of the structure of peptidoglycan precursors and their mode of polymerization. [source] Structure and function of the Mur enzymes: development of novel inhibitorsMOLECULAR MICROBIOLOGY, Issue 1 2003Ahmed El Zoeiby Summary One of the biggest challenges for recent medical research is the continuous development of new antibiotics interacting with bacterial essential mechanisms. The machinery for peptidoglycan biosynthesis is a rich source of crucial targets for antibacterial chemotherapy. The cytoplasmic steps of the biosynthesis of peptidoglycan precursor, catalysed by a series of Mur enzymes, are excellent candidates for drug development. There has been growing interest in these bacterial enzymes over the last decade. Many studies attempted to understand the detailed mechanisms and structural features of the key enzymes MurA to MurF. Only MurA is inhibited by a known antibiotic, fosfomycin. Several attempts made to develop novel inhibitors of this pathway are discussed in this review. Three novel inhibitors of MurA were identified recently. 4-Thiazolidinone compounds were designed as MurB inhibitors. Many phosphinic acid derivatives and substrate analogues were identified as inhibitors of the MurC to MurF amino acid ligases. [source] Role of phosphoglucosamine mutase on virulence properties of Streptococcus mutansMOLECULAR ORAL MICROBIOLOGY, Issue 4 2009X. D. Liu Introduction:,Streptococcus mutans has been strongly implicated as the principal etiological agent in dental caries. As a gram-positive bacterium, S. mutans has a thick and compact cell wall to maintain the cell shape and protect the cells against mechanical or osmotic damage. Previous studies have proved that peptidoglycan is the main component of the cell wall involved in the autolysis or biofilm formation processes. Methods:, In this study, we investigated the gene SMU.1426c in the amino-sugar metabolism pathway of S. mutans UA159, which encodes phosphoglucosamine mutase (GlmM). The glmM gene that functions in the biosynthesis of peptidoglycan has been well investigated in Escherichia coli. Here a glmM mutant strain of S. mutans UA159 was constructed and several virulence properties were investigated. Results:, The mutant devoid of the glmM gene displayed long chains, reduced growth rate and increased autolysis. Biofilm formation by the mutant was found to be attenuated. Conclusion:, These results proved that peptidoglycan biosynthesis plays an important part in a series of bacterial morphologies. The glmM gene may have a constructive role in the virulence properties of S. mutans. [source] Residues Asp164 and Glu165 at the substrate entryway function potently in substrate orientation of alanine racemase from E. coli: Enzymatic characterization with crystal structure analysisPROTEIN SCIENCE, Issue 6 2008Dalei Wu Abstract Alanine racemase (Alr) is an important enzyme that catalyzes the interconversion of L-alanine and D-alanine, an essential building block in the peptidoglycan biosynthesis. For the small size of the Alr active site, its conserved substrate entryway has been proposed as a potential choice for drug design. In this work, we fully analyzed the crystal structures of the native, the D-cycloserine-bound, and four mutants (P219A, E221A, E221K, and E221P) of biosynthetic Alr from Escherichia coli (EcAlr) and studied the potential roles in substrate orientation for the key residues involved in the substrate entryway in conjunction with the enzymatic assays. Structurally, it was discovered that EcAlr is similar to the Pseudomonas aeruginosa catabolic Alr in both overall and active site geometries. Mutation of the conserved negatively charged residue aspartate 164 or glutamate 165 at the substrate entryway could obviously reduce the binding affinity of enzyme against the substrate and decrease the turnover numbers in both D- to L-Ala and L- to D-Ala directions, especially when mutated to lysine with the opposite charge. However, mutation of Pro219 or Glu221 had only negligible or a small influence on the enzymatic activity. Together with the enzymatic and structural investigation results, we thus proposed that the negatively charged residues Asp164 and Glu165 around the substrate entryway play an important role in substrate orientation with cooperation of the positively charged Arg280 and Arg300 on the opposite monomer. Our findings are expected to provide some useful structural information for inhibitor design targeting the substrate entryway of Alr. [source] The 1.9 Å crystal structure of Escherichia coli MurG, a membrane-associated glycosyltransferase involved in peptidoglycan biosynthesisPROTEIN SCIENCE, Issue 6 2000Sha Ha Abstract The 1.9 Å X-ray structure of a membrane-associated glycosyltransferase involved in peptidoglycan biosynthesis is reported. This enzyme, MurG, contains two ,/, open sheet domains separated by a deep cleft. Structural analysis suggests that the C-terminal domain contains the UDP-GlcNAc binding site while the N-terminal domain contains the acceptor binding site and likely membrane association site. Combined with sequence data from other MurG homologs, this structure provides insight into the residues that are important in substrate binding and catalysis. We have also noted that a conserved region found in many UDP-sugar transferases maps to a ,/,/,/, supersecondary structural motif in the donor binding region of MurG, an observation that may be helpful in glycosyltransferase structure prediction. The identification of a conserved structural motif involved in donor binding in different UDP-sugar transferases also suggests that it may be possible to identify,and perhaps alter,the residues that help determine donor specificity. [source] Structure of d -alanine- d -alanine ligase from Thermus thermophilus HB8: cumulative conformational change and enzyme,ligand interactionsACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2009Yoshiaki Kitamura d -Alanine- d -alanine ligase (Ddl) is one of the key enzymes in peptidoglycan biosynthesis and is an important target for drug discovery. The enzyme catalyzes the condensation of two d -Ala molecules using ATP to produce d -Ala- d -Ala, which is the terminal peptide of a peptidoglycan monomer. The structures of five forms of the enzyme from Thermus thermophilus HB8 (TtDdl) were determined: unliganded TtDdl (2.3,Å resolution), TtDdl,adenylyl imidodiphosphate (2.6,Å), TtDdl,ADP (2.2,Å), TtDdl,ADP,d -Ala (1.9,Å) and TtDdl,ATP,d -Ala- d -Ala (2.3,Å). The central domain rotates as a rigid body towards the active site in a cumulative manner in concert with the local conformational change of three flexible loops depending upon substrate or product binding, resulting in an overall structural change from the open to the closed form through semi-open and semi-closed forms. Reaction-intermediate models were simulated using TtDdl-complex structures and other Ddl structures previously determined by X-ray methods. The catalytic process accompanied by the cumulative conformational change has been elucidated based on the intermediate models in order to provide new insights regarding the details of the catalytic mechanism. [source] Crystallization and initial crystallographic analysis of phosphoglucosamine mutase from Bacillus anthracisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2009Ritcha Mehra-Chaudhary The enzyme phosphoglucosamine mutase catalyzes the conversion of glucosamine 6-phosphate to glucosamine 1-phosphate, an early step in the formation of the nucleotide sugar UDP- N -acetylglucosamine, which is involved in peptidoglycan biosynthesis. These enzymes are part of the large ,- d -phosphohexomutase enzyme superfamily, but no proteins from the phosphoglucosamine mutase subgroup have been structurally characterized to date. Here, the crystallization of phosphoglucosamine mutase from Bacillus anthracis in space group P3221 by hanging-drop vapor diffusion is reported. The crystals diffracted to 2.7,Å resolution under cryocooling conditions. Structure determination by molecular replacement was successful and refinement is under way. The crystal structure of B. anthracis phosphoglucosamine mutase should shed light on the substrate-specificity of these enzymes and will also serve as a template for inhibitor design. [source] | |||||||||||||