Penicillin-binding Protein (PBP); class-C1 LMM PBP
Abstract :
[en] Bacillus subtilis PBP4a belongs to the class-C1 PBPs characterized by two internal additional domains of unknown function. Seven lysine residues (K) are protruding from domain II. Four of them: K86, K114, K119 and K265 have been mutated in glutamine residues (Q). Both proteins (WT and Mut4KQ PBP4a) have been produced without signal peptide in E. coli and their sub-cellular localizations determined by measuring the DD-carboxypeptidase activities in the different compartments (cytoplasmic vs membrane attached proteins). After purification, their binding to B. subtilis membranes has been compared: WT PBP4a interacts in vitro with membranes isolated from this organism in contrast to Mut4KQ PBP4a that remains entirely unbound. In absence of any amphiphilic peptide in PBP4a, the crown of positive charges on the surface of domain II is likely responsible for the PBP cellular localization in interaction with the cytoplasmic membrane.
