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Role of the penicillin-sensitive transpeptidation reaction in attachment of newly synthesized peptidoglycan to cell walls of Micrococcus luteus.

Authors
Type
Published Article
Journal
Proceedings of the National Academy of Sciences of the United States of America
Publication Date
Volume
69
Issue
11
Pages
3355–3359
Identifiers
PMID: 4343965
Source
Medline
License
Unknown

Abstract

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.

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