Keeping Signals Straight in Phosphorelay Signal Transduction

Abstract

The gene pbpC from Staphylococcus aureuswas sequenced: it encodes a 691-amino-acid protein with all of the conserved motifs of a class B high-molecular-weight penicillin-binding protein (PBP), including the transpeptidase conserved motifs SXXK, SXN, and KTG. Insertional inactivation of pbpC and introduction of the intact gene in a laboratory mutant missing PBP 3 showed that thepbpC gene encodes the staphylococcal PBP 3. Inactivation ofpbpC caused no detectable change in the muropeptide composition of cell wall peptidoglycan and had only minimum, if any, effect on growth rates, but caused a small but significant decrease in rates of autolysis. Cells of abnormal size and shape and disoriented septa were produced when bacteria with inactivated pbpCwere grown in the presence of a sub-MIC of methicillin.