Restoration of vegetative penicillin-binding proteins during germination and outgrowth of Bacillus subtilis spores: relationship of individual proteins to specific cell cycle events.

The order in which the vegetative penicillin-binding proteins (PBPs) are first synthesized and the rate of their return to normal levels during germination and outgrowth of Bacillus subtilis spores were determined. The rate of synthesis of most of the PBPs was much faster than that of the majority of other membrane proteins, which is consistent with the involvement of PBPs in biosynthesis of the rapidly expanding peptidoglycan. The pattern of PBP changes that occurred during the cell cycle, including sporulation, suggests a likely role for PBP 2A in cell elongation and a unique requirement for PBP 2B during both symmetric and asymmetric septum formation. PBP 3 is the only PBP that appears to be equally necessary for vegetative and cortical peptidoglycan synthesis.