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

Several beta-lactams were investigated on the affinity for the penicillin-binding proteins (PBPs) and the antibacterial activity in Bacillus subtilis. The beta-lactams such as ampicillin, PS-5, methicillin and SCE-963, which had high affinities for PBP-2 showed strong antibacterial activities and the beta-lactams such as cephamycin C, Y-G19Z-GG and Y-G19Z-G, which had high affinities for PBP-1 but low affinities for PBP-2, showed weak antibacterial activities. Clavulanic acid and nocardicin A, which had almost no affinities for all the PBPs detected, showed very low antibacterial activities. These results suggest that PBP-2 in Bacillus subtilis is the lethal target of these beta-lactam antibiotics.