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Systematic substitutions at BLIP position 50 result in changes in binding specificity for class A β-lactamases
Carolyn J Adamski1,2, Timothy Palzkill3,4
1Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.
BMC Biochemistry
|March 8, 2017
Summary
Bacterial resistance to beta-lactam antibiotics is often due to beta-lactamases. Beta-lactamase inhibitory protein (BLIP) inhibits these enzymes, but substitutions at BLIP Tyr50 show varied effects on binding specificity for different beta-lactamases.
Area of Science:
- Biochemistry
- Microbiology
- Protein Engineering
Background:
- Bacterial resistance to beta-lactam antibiotics is a significant clinical challenge.
- Beta-lactamases are enzymes produced by bacteria that confer resistance by degrading beta-lactam antibiotics.
- Beta-lactamase inhibitory protein (BLIP) is a known inhibitor of class A beta-lactamases, acting through competitive inhibition.
Purpose of the Study:
- To investigate the impact of systematic substitutions at position 50 of BLIP on its binding affinity and specificity towards class A beta-lactamases.
- To explore the role of BLIP Tyr50 as a determinant of specificity in the interaction with various beta-lactamases.
Main Methods:
- Systematic amino acid substitutions were introduced at position 50 of BLIP.
- Binding affinities of BLIP variants to different class A beta-lactamases (e.g., Bacillus anthracis Bla1, TEM-1, KPC-2) were assessed.
- Analysis of sequence requirements at BLIP position 50 for effective inhibition of target beta-lactamases.
Main Results:
- Sequence requirements at BLIP position 50 vary significantly depending on the target beta-lactamase.
- Stringent requirements were observed for binding Bacillus anthracis Bla1.
- Moderate requirements were found for TEM-1, and relaxed requirements for KPC-2 beta-lactamase.
Conclusions:
- The effect of substitutions at BLIP Tyr50 is highly dependent on the specific target beta-lactamase.
- Observed differences in binding cannot be solely explained by direct contacts at the BLIP Tyr50 site, suggesting broader interface contributions.
- Predicting the impact of substitutions at protein-protein interaction interfaces, like that of BLIP and beta-lactamases, is complex and influenced by non-local interactions.
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