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A new TEM beta-lactamase double mutant with broadened specificity reveals substrate-dependent functional interactions
1Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca.
The Journal of Biological Chemistry
|January 13, 1995
Summary
Mutations in TEM beta-lactamase enhance its activity against cephalosporins. The double mutant E104M/G238S shows a 1000-fold increase in catalytic efficiency, broadening antibiotic resistance mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzyme Kinetics
Background:
- TEM beta-lactamase is a key enzyme conferring antibiotic resistance.
- Understanding mutations that alter enzyme specificity is crucial for combating resistance.
Purpose of the Study:
- To engineer TEM beta-lactamase variants with altered substrate specificity.
- To characterize the kinetic properties of novel TEM beta-lactamase mutants.
Main Methods:
- Random combinatorial mutagenesis and selection.
- Site-directed mutagenesis and cloning.
- Enzyme kinetics and computational modeling.
Main Results:
- The double mutant E104M/G238S exhibited a 1000-fold increase in kcat/Km against cefotaxime.
- Single mutant E104M showed increased kcat, while G238S affected Km and kcat depending on the substrate.
- Computational modeling supported observed enzyme activities.
Conclusions:
- Specific mutations can significantly enhance TEM beta-lactamase activity and broaden substrate specificity.
- The combined effects of mutations can be additive or synergistic, depending on the substrate.
- Engineered TEM beta-lactamase variants provide insights into antibiotic resistance mechanisms.