title: In vitro reconstitution of peptidoglycan assembly from the Gram-positive pathogen Streptococcus pneumoniae.
abstract: Understanding the molecular basis of bacterial cell wall assembly is of paramount importance in addressing the threat of increasing antibiotic resistance worldwide. Streptococcus pneumoniae presents a particularly acute problem in this respect, as it is capable of rapid evolution by homologous recombination with related species. Resistant strains selected by treatment with β-lactams express variants of the target enzymes that do not recognize the drugs but retain their activity in cell wall building, despite the antibiotics being mimics of the natural substrate. Until now, the crucial transpeptidase activity that is inhibited by β-lactams was not amenable to in vitro investigation with enzymes from Gram-positive organisms, including streptococci, staphylococci, or enterococci pathogens. We report here for the first time the in vitro assembly of peptidoglycan using recombinant penicillin-binding proteins from pneumococcus and the precursor lipid II. The two required enzymatic activities, glycosyl transferase for elongating glycan chains and transpeptidase for cross-linking stem-peptides, were observed. Most importantly, the transpeptidase activity was dependent on the chemical nature of the stem-peptide. Amidation of the second residue glutamate into iso-glutamine by the recently discovered amido-transferase MurT/GatD is required for efficient cross-linking of the peptidoglycan.
authors.affiliation: Université Grenoble Alpes, Institut de Biologie Structurale (IBS), Grenoble F-38027, France.
authors.forename: André
authors.initials: A
authors.lastname: Zapun
authors.forename: Jules
authors.initials: J
authors.lastname: Philippe
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Abrahams
authors.forename: Luca
authors.initials: L
authors.lastname: Signor
authors.forename: David I
authors.initials: DI
authors.lastname: Roper
authors.forename: Eefjan
authors.initials: E
authors.lastname: Breukink
authors.forename: Thierry
authors.initials: T
authors.lastname: Vernet
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005818:Genetic Engineering; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D059765:Homologous Recombination; D046915:Penicillin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D046928:Peptidoglycan Glycosyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010458:Peptidyl Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D018440:beta-Lactam Resistance / Q000187:drug effects / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D014538:Uridine Diphosphate N-Acetylmuramic Acid; D047090:beta-Lactams; C069249:muramyl-NAc-(pentapeptide)pyrophosphoryl-undecaprenol; D005973:Glutamine; D018698:Glutamic Acid; D010458:Peptidyl Transferases; D046928:Peptidoglycan Glycosyltransferase