Biosynthesis of the Peptidoglycan of Bacterial Cell Walls

The lipid intermediates in peptidoglycan synthesis in Staphylococcus aureus, N-acetylmuramyl(-pentapeptide)-P-P-lipid and N-acetylglucosaminyl-N-acetylmuramyl(-pentapeptide)-P-P-lipid, act as acceptors of ammonia in an ATP-dependent reaction in which the α-carboxyl group of glutamic acid is amidated. Procedures have been developed for the separation of the amide and the amide-free forms of the lipid intermediates, and it has been shown that the amide-free lipid intermediate can substitute for the uridine nucleotide substrates in the amidation reaction. Some properties of the reaction are reported.