Abstract:
Escherichia coli (E. coli) has four known DD-carboxypeptidases (DD-CPases), namely
penicillin-binding protein (PBP) 4, 5, 6, and DacD, and are thought to restrict the
unwanted crosslink formation between the nascent peptidoglycan strands. So far, the in
vivo functions of these enzymes are mostly unknown, except for PBP 5, which helps
maintain cell shape. In spite of high degree of identity, PBP 6 is unable to imitate the
shape maintaining activity of PBP 5. A 20 amino acids (aa) segment near to the KTG
motif forms the morphology maintenance domain (MMD) in PBP 5 and the replacement
of the corresponding amino acids of PBP 6 with that of PBP 5 MMD restores normal
morphology in E. coli.
