A novel assay of bacterial peptidoglycan synthesis for natural product screening.

Although a large number of microbial metabolites have been discovered as inhibitors of bacterial peptidoglycan biosynthesis, only a few inhibitors were reported for the pathway of UDP-MurNAc-pentapeptide formation, partly because of the lack of assays appropriate for natural product screening. Among the pathway enzymes, D-Ala racemase (Alr), D-Ala:D-Ala ligase (Ddl) and UDP-MurNAc-tripeptide:D-Ala-D-Ala transferase (MurF) are particularly attractive as antibacterial targets, because these enzymes are essential for growth and utilize low-molecular-weight substrates. Using dansylated UDP-MurNAc-tripeptide and L-Ala as the substrates, we established a cell-free assay to measure the sequential reactions of Alr, Ddl and MurF coupled with translocase I.

Studies on novel bacterial translocase I inhibitors, A-500359s. V. Enhanced production of capuramycin and A-500359 A in Streptomyces griseus SANK 60196.

Streptomyces griseus SANK 60196 produces the novel nucleoside antibiotics A-500359 A, C, D and capuramycin. Enhanced production of capuramycin and A-500359 A was achieved through a number of medium modifications and a series of single colony isolations. The addition of maltose instead of glucose as the carbon source in a primary medium resulted in a 20-fold increase in the productivity of capuramycin.