Approaching the physiological functions of penicillin-binding proteins in Escherichia coli

A rigid shell of peptidoglycan encases and shapes bacteria and is construct ed and maintained by a diverse set of enzymes. among which are the penicill in-binding proteins (PBPs). Although a great deal has been learned about ho w these proteins synthesize and modify peptidoglycan, the physiological fun ctions of the multitude of bacterial PBPs remain enigmatic. We approached t his problem by combining PBP mutations in a comprehensive manner and screen ing for effects on biochemical processes involving the passage of proteins or nucleic acids across the cell wall. The results indicate that the PBPs o r their peptidoglycan product do have significant biological functions, inc luding roles in determination of cell shape, in phage resistance, in induct ion of capsule synthesis, and in regulation of autolysis. (C) 2001 Societe francaise de biochimie et biologie moleculaire / Editions scientifiques et medicales Elsevier SAS.