Penicillin-binding proteins in Streptomyces cacaoi. The effects on penicillin-binding proteins and the antibacterial activities of beta-lactams.

Penicillin-binding proteins (PBPs) in membrane of Streptomyces cacaoi were investigated by sodium dodecylsulfate-polyacrylamide gel electrophoresis-fluorography. At the same time, eleven beta-lactams were examined on the affinities for these PBPs and the antibacterial activities against S. cacaoi, comparing with those in Bacillus subtilis reported in the preceding paper. The affinity patterns of beta-lactams for PBPs both in S. cacaoi and B. subtilis were similar in many points. Here again, the grouping of beta-lactams based on the affinity for PBP-2 (M. W., 91,000) was in accord with that based on the antibacterial activity. These results suggest that among PBPs detected in S. cacaoi, PBP-2 is the most likely target of killing by these beta-lactam antibiotics.