title: Distinct effects of the UvrD helicase on topoisomerase-quinolone-DNA ternary complexes.
abstract: Quinolone antibacterial drugs target both DNA gyrase (Gyr) and topoisomerase IV (Topo IV) and form topoisomerase-quinolone-DNA ternary complexes. The formation of ternary complexes results in the inhibition of DNA replication and leads to the generation of double-strand breaks and subsequent cell death. Here, we have studied the consequences of collisions between the UvrD helicase and the ternary complexes formed with either Gyr, Topo IV, or a mutant Gyr, Gyr (A59), which does not wrap the DNA strand around itself. We show (i) that Gyr-norfloxacin (Norf)-DNA and Topo IV-Norf-DNA, but not Gyr (A59)-Norf-DNA, ternary complexes inhibit the UvrD-catalyzed strand-displacement activity, (ii) that a single-strand break is generated at small portions of the ternary complexes upon their collisions with UvrD, and (iii) that the majority of Topo IV-Norf-DNA ternary complexes become nonreversible when UvrD collides with the Topo IV-Norf-DNA ternary complexes, whereas the majority of Gyr-Norf-DNA ternary complexes remain reversible after their collision with the UvrD helicase. These results indicated that different DNA repair mechanisms might be involved in the repair of Gyr-Norf-DNA and Topo IV-Norf-DNA ternary complexes.
authors.affiliation: Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Shea
authors.forename: H
authors.initials: H
authors.lastname: Hiasa
mesh_terms: D042462:4-Quinolones; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000890:Anti-Infective Agents / Q000378:metabolism*; D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism*; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*
chemical_list: D042462:4-Quinolones; D000890:Anti-Infective Agents; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II