Functional determinants of gate-DNA selection and cleavage by bacterial type II topoisomerases.

ABSTRACT: Antibacterial fluoroquinolones trap a cleavage complex of gyrase and topoisomerase (topo) IV inducing site-specific DNA breakage within a bent DNA gate engaged in DNA transport. Despite its importance for drug action and in revealing potential sites of topoisomerase catalysis, the mechanism of DNA selectivity is poorly understood. To explore its functional basis, we generated mutant versions of the strongly cleaved E-site and used a novel competitive assay to examine their gemifloxacin-mediated DNA breakage by Streptococcus pneumoniae topo IV and gyrase. Parallel studies of Ca(2+)-induced cleavage distinguished 'intrinsic recognition' of DNA cleavage sites by topo IV from drug-induced preferences. Analysis revealed strong enzyme-determined requirements for -4G, -2A and -1T bases preceding

SUBMITTER: Arnoldi E 

PROVIDER: S-EPMC3814380 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature