title: Functional Analyses of the Toxoplasma gondii DNA Gyrase Holoenzyme: A Janus Topoisomerase with Supercoiling and Decatenation Abilities.
abstract: A number of important protozoan parasites including those responsible for toxoplasmosis and malaria belong to the phylum Apicomplexa and are characterised by their possession of a relict plastid, the apicoplast. Being required for survival, apicoplasts are potentially useful drug targets and their attractiveness is increased by the fact that they contain "bacterial" gyrase, a well-established antibacterial drug target. We have cloned and purified the gyrase proteins from the apicoplast of Toxoplasma gondii (the cause of toxoplasmosis), reconstituted the functional enzyme and succeeded in characterising it. We discovered that the enzyme is inhibited by known gyrase inhibitors and that, as well as the expected supercoiling activity, it is also able to decatenate DNA with high efficiency. This unusual dual functionality may be related to the apparent lack of topoisomerase IV in the apicoplast.
authors.affiliation: Heddle Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lin
authors.affiliation: Heddle Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Soshichiro
authors.initials: S
authors.lastname: Nagano
authors.affiliation: Heddle Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gardiner Heddle
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D027081:DNA Gyrase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D026942:DNA Topoisomerases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D020035:Holoenzymes; D020128:Inhibitory Concentration 50; D055503:Protein Multimerization; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D014122:Toxoplasma / Q000378:metabolism*
chemical_list: D020035:Holoenzymes; D059005:Topoisomerase II Inhibitors; D004247:DNA; D000251:Adenosine Triphosphatases; D026942:DNA Topoisomerases; D027081:DNA Gyrase; D002118:Calcium