Penicillin-binding proteins of listeria monocytogenes--a re-evaluation.

Intact Listeria monocytogenes cells or membranes isolated from them were treated with [3H]penicillin to allow identification of the penicillin binding proteins (PBPs) located in the cytoplasmic membrane. In the former case the PBPs were released from the cells following disruption of the cell wall murein with Listeria monocytogenes bacteriophage lysin. The procedure described by Dougherty et al. (1996) for Escherichia coli, with some modifications, was used to evaluate the M(r)s of the individual PBPs and allowed direct quantitation of their copy number.