Changes in penicillin-binding proteins during sporulation of Bacillus subtilis.

The penicillin-binding proteins (PBPs) of Bacillus subtilis were examined in samples collected at various times from sporulating cultures and compared with the PBPs in a presporulation sample. Large increases in vegetative PBPs 2B and 3 and the appearance of at least one new PBP (42,000 daltons) occurred at reproducible times during sporulation. In some strains a second new PBP (60,000 daltons) was also produced. By comparing the PBP activities in sporulating cells and two spo0 mutants we have classified these changes as sporulation-related events rather than the consequences of stationary-phase aging. The other vegetative PBPs (PBPs 1, 2A, 4, and 5) decreased during sporulation, but not in sufficient amount or at the appropriate time to account for the appearance of the new proteins. A possible connection between specific PBP changes and the penicillin-sensitive stages of sporulation is suggested.