title: Biosynthesis of peptidoglycan in Staphylococcus aureus: incorporation of the Nepsilon-Ala-Lys moiety into the peptide subunit of nascent peptidoglycan.
abstract: UDP-MurNAc-Ala-DGlu-Lys(Nepsilon-Ala)-DAla-DAla was isolated from extracts of Staphylococcus aureus Copenhagen. This nucleotide accumulated in media deficient in glycine. To establish its role in peptidoglycan biosynthesis, the nucleotide-hexapeptide was compared with UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla in the reaction catalyzed by phospho-MurNAc-pentapeptide translocase and in the membrane-catalyzed nascent peptidoglycan-synthetizing system. In the exchange reaction catalyzed by the translocase, the Rmax and Rmax/Km are 1.79 muM/min and 4.47 X 10(-2)/min, respectively, for UDP-MurNAc-pentapeptide and 1.81 muM/min and 4.46 X 10(-2)/min, respectively, for UDP-Mur-NAc-hexapeptide. In the synthesis of nascent peptidoglycan, the Vmax is 1.8 muM/min X 10(-2) for both the nucleotide-hexapeptide and -pentapeptide. The Vmax/Km is 5.6 X 10(-4) and 4.3 X 10(-4)/min for the nucleotide-pentapeptide and -hexapeptide, respectively. Schleifer, Hammes, and Kandler (Adv. Microb. Physiol. in press) observed that growth of S. aureus Copenhagen on a glycine-poor medium results in a peptidoglycan structure in which 20% of the lysine residues are substituted at the epsilon-amino group by L-alanine residues that do not participate in interpeptide bridge information. The in vitro studies demonstrate that UDP-MurNAc-Ala-DGlu-Lys(Nepsilon-Ala)-DAla-DAla is a possible precursor of the Nepsilon-Ala-Lys moiety.
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002474:Cell-Free System; D005998:Glycine / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism*; D010400:Penicillin G / Q000494:pharmacology; D010452:Peptide Biosynthesis; D010455:Peptides / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis*; D010770:Phosphotransferases / Q000378:metabolism; D013211:Staphylococcus aureus / Q000201:enzymology / Q000378:metabolism*
chemical_list: D009711:Nucleotides; D010455:Peptides; D010457:Peptidoglycan; D010770:Phosphotransferases; D010400:Penicillin G; D005998:Glycine; D000117:Acetylglucosamine