Mode of peptidoglycan synthesis in Salmonella typhimurium: single-strand insertion

The synthesis of peptidoglycan by Salmonella typhimurium at the molecular level has been analyzed by studying the pattern of insertion of newly synthesized strands into the preexisting cell wall. We have measured the acceptor-donor radioactivity ratio during short labeling periods, and we found values between 0 and 0.2. This is less than the ratio observed by Burman and Park (Proc. Natl. Acad. Sci. USA, 81:1844-1848) for peptidoglycan synthesis in Escherichia coli. We propose that insertion of new strands occurs as single strands.