PBP1 is a component of the Bacillus subtilis cell division machinery

Bacillus subtilis penicillin-binding protein PBP1 has been implicated in cell division. We show here that a PBP1 knockout strain is affected in the formation of the asymmetric sporulation septum and that green fluorescent protein-PBP1 localizes to the sporulation septum. Localization of PBP1 to the vegetative septum is dependent on various cell division proteins. This study proves that PBP1 forms part of the B. subtilis cell division machinery. The cell wall is the principal shape-maintaining and stress-bearing element of the bacterial cell (for reviews, see refer-ences 9, 12, and 24). The Bacillus subtilis cell wall consists of peptidoglycan (PG), glycan strands with peptide side chains that are highly cross-linked, and covalently linked anionic poly-mers (9). The polymerization and cross-linking of PG is medi-ated by penicillin-binding proteins (PBPs). Various studies have indicated that PG synthesis is likely to be mediated by holoenzyme complexes, comprising PBPs and lytic transglyco-sylases that can perform the murein synthesis and hydrolysi