title: Transpeptidase-mediated incorporation of D-amino acids into bacterial peptidoglycan.
abstract: The β-lactams are the most important class of antibiotics in clinical use. Their lethal targets are the transpeptidase domains of penicillin binding proteins (PBPs), which catalyze the cross-linking of bacterial peptidoglycan (PG) during cell wall synthesis. The transpeptidation reaction occurs in two steps, the first being formation of a covalent enzyme intermediate and the second involving attack of an amine on this intermediate. Here we use defined PG substrates to dissect the individual steps catalyzed by a purified E. coli transpeptidase. We demonstrate that this transpeptidase accepts a set of structurally diverse D-amino acid substrates and incorporates them into PG fragments. These results provide new information on donor and acceptor requirements as well as a mechanistic basis for previous observations that noncanonical D-amino acids can be introduced into the bacterial cell wall.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Tania J
authors.initials: TJ
authors.lastname: Lupoli
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsukamoto
authors.forename: Emma H
authors.initials: EH
authors.lastname: Doud
authors.forename: Tsung-Shing Andrew
authors.initials: TS
authors.lastname: Wang
authors.forename: Suzanne
authors.initials: S
authors.lastname: Walker
authors.forename: Daniel
authors.initials: D
authors.lastname: Kahne
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism*; D010458:Peptidyl Transferases / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D010457:Peptidoglycan; D010458:Peptidyl Transferases