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The G132S mutation enhances the resistance of Mycobacterium tuberculosis β-lactamase against sulbactam

DOI: 10.1021/acs.biochem.1c00168 DOI Help

Authors: Ilona Van Alen (Leiden University) , Aleksandra Chikunova (Leiden University) , Adil A. Safeer (Leiden University) , Misbha Ud Din Ahmad (The Netherlands Cancer Institute) , Anastassis Perrakis (The Netherlands Cancer Institute) , Marcellus Ubbink (Leiden University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biochemistry

State: Published (Approved)
Published: July 2021
Diamond Proposal Number(s): 19800

Open Access Open Access

Abstract: The current rise of antibiotic resistant forms of Mycobacterium tuberculosis is a global health threat that calls for new antibiotics. The β-lactamase BlaC of this pathogen prevents the use of β-lactam antibiotics, except in combination with a β-lactamase inhibitor. To understand if exposure to such inhibitors can easily result in resistance, a BlaC evolution experiment was performed, studying the evolutionary adaptability against the inhibitor sulbactam. Several amino acid substitutions in BlaC were shown to confer reduced sensitivity to sulbactam. The G132S mutation causes a reduction in the rate of nitrocefin and ampicillin hydrolysis and simultaneously reduces the sensitivity for sulbactam inhibition. Introduction of the side chain moiety of Ser132 causes the 104–105 peptide bond to assume the cis conformation and the side chain of Ser104 to be rotated toward the sulbactam adduct with which it forms a hydrogen bond not present in the wild-type enzyme. The gatekeeper residue Ile105 also moves. These changes in the entrance of the active site can explain the decreased affinity of G132S BlaC for both substrates and sulbactam. Our results show that BlaC can easily acquire a reduced sensitivity for sulbactam, with a single-amino acid mutation, which could hinder the use of combination therapies.

Journal Keywords: Adducts; Peptides and proteins; Genetics; Crystal structure; Inhibitors

Diamond Keywords: Tuberculosis (TB); Bacteria; Enzymes

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I04-Macromolecular Crystallography

Other Facilities: PXIII at Swiss Light Source

Added On: 18/07/2021 09:13


Discipline Tags:

Pathogens Antibiotic Resistance Infectious Diseases Health & Wellbeing Biochemistry Genetics Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)