title: Molecular basis of gyrase poisoning by the addiction toxin CcdB.
abstract: Gyrase is an ubiquitous bacterial enzyme that is responsible for disentangling DNA during DNA replication and transcription. It is the target of the toxin CcdB, a paradigm for plasmid addiction systems and related bacterial toxin-antitoxin systems. The crystal structure of CcdB and the dimerization domain of the A subunit of gyrase (GyrA14) dictates an open conformation for the catalytic domain of gyrase when CcdB is bound. The action of CcdB is one of a wedge that stabilizes a dead-end covalent gyrase:DNA adduct. Although CcdB and GyrA14 form a globally symmetric complex where the two 2-fold axes of both dimers align, the complex is asymmetric in its details. At the centre of the interaction site, the Trp99 pair of CcdB stacks with the Arg462 pair of GyrA14, explaining why the Arg462Cys mutation in the A subunit of gyrase confers resistance to CcdB. Overexpression of GyrA14 protects Escherichia coli cells against CcdB, mimicking the action of the antidote CcdA.
authors.affiliation: Laboratorium voor Ultrastructuur, Vrije Universiteit Brussel and Department of Molecular and Cellular Interactions, Vlaams Instituut voor Biotechnologie, Building E, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Minh-Hoa
authors.initials: MH
authors.lastname: Dao-Thi
authors.forename: Laurence
authors.initials: L
authors.lastname: Van Melderen
authors.forename: Erwin
authors.initials: E
authors.lastname: De Genst
authors.forename: Hassan
authors.initials: H
authors.lastname: Afif
authors.forename: Lieven
authors.initials: L
authors.lastname: Buts
authors.forename: Lode
authors.initials: L
authors.lastname: Wyns
authors.forename: Remy
authors.initials: R
authors.lastname: Loris
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D003461:Crystallography; D027081:DNA Gyrase / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D005144:F Factor / Q000235:genetics / Q000502:physiology; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D059005:Topoisomerase II Inhibitors
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; C068356:CcdB protein, Plasmid F; D059005:Topoisomerase II Inhibitors; D027081:DNA Gyrase