A large displacement of the SXN motif of Cys115-modified penicillin-binding protein 5 from Escherichia coli.Nicola, G., Fedarovich, A., Nicholas, R.A., Davies, C.
(2005) Biochem.J. 392: 55-63
- PubMed: 16038617
- DOI: 10.1042/BJ20050449
- Primary Citation of Related Structures:  1SDN
- PubMed Abstract:
- Effects of sulfhydryl reagents on the binding and release of penicillin G by D-alanine carboxypeptidase 1A of Escherichia coli
Curtis, S.J.,Strominger, J.L.
(1978) J.Biol.Chem. 253: 2584
- CRYSTAL STRUCTURE OF A DEACYLATION-DEFECTIVE MUTANT OF PENICILLIN-BINDING PROTEIN 5 AT 2.3 A RESOLUTION
Davies, C.,White, S.W.,Nicholas, R.A.
(2001) J.Biol.Chem. 276: 616
Penicillin-binding proteins (PBPs), which are the lethal targets of beta-lactam antibiotics, catalyse the final stages of peptidoglycan biosynthesis of the bacterial cell wall. PBP 5 of Escherichia coli is a D-alanine CPase (carboxypeptidase) that ha ...
Penicillin-binding proteins (PBPs), which are the lethal targets of beta-lactam antibiotics, catalyse the final stages of peptidoglycan biosynthesis of the bacterial cell wall. PBP 5 of Escherichia coli is a D-alanine CPase (carboxypeptidase) that has served as a useful model to elucidate the catalytic mechanism of low-molecular-mass PBPs. Previous studies have shown that modification of Cys115 with a variety of reagents results in a loss of CPase activity and a large decrease in the rate of deacylation of the penicilloyl-PBP 5 complex [Tamura, Imae and Strominger (1976) J. Biol. Chem. 251, 414-423; Curtis and Strominger (1978) J. Biol. Chem. 253, 2584-2588]. The crystal structure of wild-type PBP 5 in which Cys115 fortuitously had formed a covalent adduct with 2-mercaptoethanol was solved at 2.0 A (0.2 nm) resolution, and these results provide a structural rationale for how thiol-directed reagents lower the rate of deacylation. When compared with the structure of the unmodified wild-type enzyme, a major change in the architecture of the active site is observed. The two largest differences are the disordering of a loop comprising residues 74-90 and a shift in residues 106-111, which results in the displacement of Ser110 of the SXN active-site motif. These results support the developing hypothesis that the SXN motif of PBP 5, and especially Ser110, is intimately involved in the catalytic mechanism of deacylation.
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.