Role of the penicillin-sensitive transpeptidation reaction in attachment of newly synthesized peptidoglycan to cell walls of Micrococcus luteus.
Cell-wall preparations of Micrococcus luteus (lysodeikticus) catalyze in vitro peptidoglycan synthesis from UDP N-acetyl-D-glucosamine, UDP N-acetylmuramic acid-pentapeptide, and glycine. Newly synthesized peptidoglycan is partially cross-linked by a transpeptidation reaction with concomitant release of C-terminal D-alanine. Penicillin not only strongly inhibits release of D-alanine (98% at 1 mug/ml), but also markedly inhibits incorporation of acetylglucosamine and N-acetylmuramic acid-pentapeptide into the preformed cell-wall peptidoglycan. The simplest explanation for the results is that incorporation of newly synthesized strands of peptidoglycan and their attachment to "older" cell-wall peptidoglycan proceeds mainly by transpeptidation and that transglycosylation is responsible only for part of the elongation of the pre-existing peptidoglycan. Another possibility is that incorporation occurs by transglycosylation, but it cannot continue without concurrent formation of peptide cross-bridges.
D000596:Amino Acids / Q000378:metabolism; D002247:Carbon Isotopes; D002473:Cell Wall / Q000378:metabolism; D002509:Cephaloridine / Q000494:pharmacology; D005944:Glucosamine / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D008712:Methicillin / Q000494:pharmacology; D008837:Micrococcus / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D009112:Muramic Acids / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D010397:Penicillanic Acid / Q000494:pharmacology; D010400:Penicillin G / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology*; D010455:Peptides / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D014539:Uridine Diphosphate Sugars / Q000378:metabolism
D000596:Amino Acids; D002247:Carbon Isotopes; D009112:Muramic Acids; D009842:Oligopeptides; D010406:Penicillins; D010455:Peptides; D010457:Peptidoglycan; D011498:Protein Precursors; D014539:Uridine Diphosphate Sugars; D010397:Penicillanic Acid; D002509:Cephaloridine; D005944:Glucosamine; D010400:Penicillin G; D008712:Methicillin; D005998:Glycine