title: Mycobacterium tuberculosis DNA gyrase possesses two functional GyrA-boxes.
abstract: In contrast with most bacteria which possess two type II topoisomerases (topoisomerase IV and DNA gyrase), Mycobacterium tuberculosis possesses only one, DNA gyrase, which is functionally a hybrid enzyme. Functional differences between the two type IIA topoisomerases are thought to be specified by a CTD (C-terminal DNA-binding domain), which controls DNA recognition. To explore the molecular mechanism responsible for the hybrid functions of the M. tuberculosis DNA gyrase, we conducted a series of sequence analyses and structural and biochemical experiments with the isolated GyrA CTD and the holoenzyme. Although the CTD displayed a global structure similar to that of bona fide GyrA and ParC paralogues, it harbours a second key motif similar in all respects to that of the conserved GyrA-box sequence motif. Biochemical assays showed that the GyrA-box is responsible for DNA supercoiling, whereas the second GyrA-box-l (GyrA-box-like motif) is responsible for the enhanced decatenation activity, suggesting that the mechanistic originality of M. tuberculosis DNA gyrase depends largely on the particular DNA path around the CTD allowed for by the presence of GyrA-box-l. The results of the present study also provide, through phylogenetic exploration of the entire Corynebacterineae suborder, a new and broader insight into the functional diversity of bacterial type IIA topoisomerases.
authors.affiliation: *UPMC Université Paris 06, ER5, EA 1541, Laboratoire de Bactériologie-Hygiène, 91 bd de l'Hôpital, F 75013 Paris, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Bouige
authors.forename: Amélie
authors.initials: A
authors.lastname: Darmon
authors.forename: Jérémie
authors.initials: J
authors.lastname: Piton
authors.forename: Mélanie
authors.initials: M
authors.lastname: Roue
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Petrella
authors.forename: Estelle
authors.initials: E
authors.lastname: Capton
authors.forename: Patrick
authors.initials: P
authors.lastname: Forterre
authors.forename: Alexandra
authors.initials: A
authors.lastname: Aubry
authors.forename: Claudine
authors.initials: C
authors.lastname: Mayer
mesh_terms: D027081:DNA Gyrase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D020035:Holoenzymes; D027081:DNA Gyrase