A point mutation leads to altered product specificity in β-lactamase catalysis
| Autor: | Kelly M. Winterberg, Anthony L. Fink, Evan R. Lewis |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Magnetic Resonance Spectroscopy
Stereochemistry Bacillus Carboxypeptidases Catalysis Mass Spectrometry beta-Lactamases Substrate Specificity Structure-Activity Relationship Leucine Point Mutation Structure–activity relationship Asparagine Bacillus licheniformis Chromatography High Pressure Liquid chemistry.chemical_classification Multidisciplinary biology Point mutation Penicillin G Biological Sciences biology.organism_classification Carboxypeptidase Enzyme chemistry Covalent bond biology.protein |
| Zdroj: | Proceedings of the National Academy of Sciences. 94:443-447 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.94.2.443 |
| Popis: | β-Lactamases are the primary cause of β-lactam antibiotic resistance in many pathogenic organisms. The β-lactamase catalytic mechanism has been shown to involve a covalent acyl-enzyme. Examination of the structure of the class A β-lactamase from Bacillus licheniformis suggested that replacement of Asn-170 by leucine would disrupt the deacylation reaction by displacing the hydrolytic water molecule. When N170L β-lactamase was reacted with penicillins, a novel product was formed. We postulate that with leucine at position 170 the acyl-enzyme undergoes deacylation by an intramolecular rearrangement (rather than hydrolysis) to form a thiazolidine–oxazolinone as the initial product. The oxazolinone subsequently undergoes rapid breakdown leading to the formation of N -phenylacetylglycine and N -formylpenicillamine. This appears to be the first reported case where a point mutation leads to a change in enzyme mechanism resulting in a substantially altered product, effectively changing the product specificity of β-lactamase into that of d -Ala- d -Ala-carboxypeptidase interacting with benzylpenicillin. |
| Databáze: | OpenAIRE |
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