1hd8
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as a | + | Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as a d-alanine carboxypeptidase, cleaving the C-terminal d-alanine residue from cell wall peptides. Like all PBPs, PBP 5 forms a covalent acyl-enzyme complex with beta-lactam antibiotics; however, PBP 5 is distinguished by its high rate of deacylation of the acyl-enzyme complex (t(12) approximately 9 min). A Gly-105 --> Asp mutation in PBP 5 markedly impairs this beta-lactamase activity (deacylation), with only minor effects on acylation, and promotes accumulation of a covalent complex with peptide substrates. To gain further insight into the catalytic mechanism of PBP 5, we determined the three-dimensional structure of the G105D mutant form of soluble PBP 5 (termed sPBP 5') at 2.3 A resolution. The structure is composed of two domains, a penicillin binding domain with a striking similarity to Class A beta-lactamases (TEM-1-like) and a domain of unknown function. In addition, the penicillin-binding domain contains an active site loop spatially equivalent to the Omega loop of beta-lactamases. In beta-lactamases, the Omega loop contains two amino acids involved in catalyzing deacylation. This similarity may explain the high beta-lactamase activity of wild-type PBP 5. Because of the low rate of deacylation of the G105D mutant, visualization of peptide substrates bound to the active site may be possible. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Davies, C.]] | [[Category: Davies, C.]] | ||
| - | [[Category: Nicholas, R | + | [[Category: Nicholas, R A.]] |
| - | [[Category: White, S | + | [[Category: White, S W.]] |
[[Category: dd-carboxypeptidase]] | [[Category: dd-carboxypeptidase]] | ||
[[Category: hydrolase]] | [[Category: hydrolase]] | ||
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[[Category: peptidoglycan synthesis]] | [[Category: peptidoglycan synthesis]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:00:02 2008'' |
Revision as of 11:00, 21 February 2008
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CRYSTAL STRUCTURE OF A DEACYLATION-DEFECTIVE MUTANT OF PENICILLIN-BINDING PROTEIN 5 AT 2.3 A RESOLUTION
Overview
Penicillin-binding protein 5 (PBP 5) of Escherichia coli functions as a d-alanine carboxypeptidase, cleaving the C-terminal d-alanine residue from cell wall peptides. Like all PBPs, PBP 5 forms a covalent acyl-enzyme complex with beta-lactam antibiotics; however, PBP 5 is distinguished by its high rate of deacylation of the acyl-enzyme complex (t(12) approximately 9 min). A Gly-105 --> Asp mutation in PBP 5 markedly impairs this beta-lactamase activity (deacylation), with only minor effects on acylation, and promotes accumulation of a covalent complex with peptide substrates. To gain further insight into the catalytic mechanism of PBP 5, we determined the three-dimensional structure of the G105D mutant form of soluble PBP 5 (termed sPBP 5') at 2.3 A resolution. The structure is composed of two domains, a penicillin binding domain with a striking similarity to Class A beta-lactamases (TEM-1-like) and a domain of unknown function. In addition, the penicillin-binding domain contains an active site loop spatially equivalent to the Omega loop of beta-lactamases. In beta-lactamases, the Omega loop contains two amino acids involved in catalyzing deacylation. This similarity may explain the high beta-lactamase activity of wild-type PBP 5. Because of the low rate of deacylation of the G105D mutant, visualization of peptide substrates bound to the active site may be possible.
About this Structure
1HD8 is a Single protein structure of sequence from Escherichia coli. Active as Serine-type D-Ala-D-Ala carboxypeptidase, with EC number 3.4.16.4 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Crystal structure of a deacylation-defective mutant of penicillin-binding protein 5 at 2.3-A resolution., Davies C, White SW, Nicholas RA, J Biol Chem. 2001 Jan 5;276(1):616-23. PMID:10967102
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