Cloning, characterization, and inactivation of the gene pbpC, encoding penicillin-binding protein 3 of Staphylococcus aureus

The gene pbpC from Staphylococcus aureus was sequenced: it encodes a 691-am ino-acid protein with all of the conserved motifs of a class B high-molecul ar-weight penicillin-binding protein (PBP), including the transpeptidase co nserved motifs SXXK, SXN, and KTG, Insertional inactivation of pbpC and int roduction of the intact gene in a laboratory mutant missing PBP 3 showed th at the pbpC gene encodes the staphylococcal PBP 3. Inactivation of pbpC cau sed no detectable change in the muropeptide composition of cell wall peptid oglycan and had only minimum, if any, effect on growth rates, but caused a small but significant decrease in rates of autolysis, Cells of abnormal siz e and shape and disoriented septa were produced when bacteria with inactiva ted pbpC were grown in the presence of a sub-MIC of methicillin.