Physiological functions of D-alanine carboxypeptidases in Escherichia coli.
Bacterial cell shape is, in part, mediated by the peptidoglycan (murein) sacculus. Penicillin-binding proteins (PBPs) catalyze the final stages of murein biogenesis and are the targets of beta-lactam antibiotics. Several low molecular mass PBPs including PBP4, PBP5, PBP6 and DacD seem to possess DD-carboxypeptidase (DD-CPase) activity, but these proteins are dispensable for survival in laboratory culture. The physiological functions of DD-CPases in vivo are unresolved and it is unclear why bacteria retain these seemingly non-essential and enzymatically redundant enzymes. However, PBP5 clearly contributes to maintenance of cell shape in some PBP mutant backgrounds. In this review, we focus on recent findings concerning the physiological functions of the DD-CPases in vivo, identify gaps in the current knowledge of these proteins and suggest some possible courses for future study that might help reconcile current models of bacterial cell morphology.
Department of Biotechnology, Indian Institute of Technology, Kharagpur, District-West Midnapore, West Bengal, PIN-721302, India. anindyain@yahoo.com
Anindya S
AS
Ghosh
Chiranjit
C
Chowdhury
David E
DE
Nelson
D002268:Carboxypeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D046915:Penicillin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D029968:Escherichia coli Proteins; D046915:Penicillin-Binding Proteins; D002268:Carboxypeptidases; C019632:alanine carboxypeptidase