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Crystal Structure of a Deacylation-defective Mutant of Penicillin-binding Protein 5 at 2.3-Å Resolution
- Source :
- Journal of Biological Chemistry. 276:616-623
- Publication Year :
- 2001
- Publisher :
- Elsevier BV, 2001.
-
Abstract
- 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.
- Subjects :
- Models, Molecular
Penicillin binding proteins
Stereochemistry
Acylation
Molecular Sequence Data
Mutant
Peptide
Penicillins
Muramoylpentapeptide Carboxypeptidase
Crystallography, X-Ray
Biochemistry
Protein Structure, Secondary
beta-Lactamases
Bacterial Proteins
Hydrolase
Escherichia coli
polycyclic compounds
Penicillin-Binding Proteins
Amino Acid Sequence
Molecular Biology
chemistry.chemical_classification
Binding Sites
biology
Active site
Cell Biology
Carboxypeptidase
Protein Structure, Tertiary
Amino acid
Kinetics
Hexosyltransferases
chemistry
Mutation
Peptidyl Transferases
biology.protein
Penicillin binding
Carrier Proteins
Sequence Alignment
Protein Binding
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 276
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....27345d1dd02d50ba72e5c1c520c02d0c