Positive epistasis drives clavulanic acid resistance in double mutant libraries of BlaC β-lactamase.

ABSTRACT: Phenotypic effects of mutations are highly dependent on the genetic backgrounds in which they occur, due to epistatic effects. To test how easily the loss of enzyme activity can be compensated for, we screen mutant libraries of BlaC, a β-lactamase from Mycobacterium tuberculosis, for fitness in the presence of carbenicillin and the inhibitor clavulanic acid. Using a semi-rational approach and deep sequencing, we prepare four double-site saturation libraries and determine the relative fitness effect for 1534/1540 (99.6%) of the unique library members at two temperatures. Each library comprises variants of a residue known to be relevant for clavulanic acid resistance as well as residue 105, which regulates access to the active site. Variants with greatly improved fitness were identified with

SUBMITTER: Radojkovic M 

PROVIDER: S-EPMC10874438 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature