title: Characterisation of the DNA gyrase from the thermophilic eubacterium Thermus thermophilus.
abstract: DNA gyrase is a type IIA topoisomerase found in bacteria but not in humans. The enzyme is required for bacterial DNA replication and transcription, and is an important antibacterial target that is sensitive to the widely-used fluoroquinolone drugs. Due to the emergence of fluoroquinolone resistance, the discovery of new classes of drugs that target DNA gyrase is urgent. The DNA gyrase holoenzyme is a heterodimer of subunit pairs (A2B2). The 90 kDa A subunits bind, cleave, and rejoin double stranded DNA. The enzyme introduces negative supercoils into closed circular bacterial DNA using ATP hydrolysis catalysed by the 70 kDa B subunits. Subdomains of DNA gyrase subunits have been crystallised for structural analysis and the resulting models used to improve drugs that target the DNA binding region and active site. While crystal structures are available for topoisomerase IV complexes with cleaved DNA, there is none for the complete DNA gyrase complex with substrate DNA bound. Thermophiles offer significant advantages in obtaining stable enzymes for structural and functional studies. In order to develop a capability for drug screening and structure-directed drug discovery we have reconstituted a functional and drug-sensitive DNA gyrase complex using heterologously expressed subunits from the thermophile Thermus thermophilus.
authors.affiliation: Department of Oral Sciences, School of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Htin Lin
authors.initials: HL
authors.lastname: Aung
authors.affiliation: Department of Oral Sciences, School of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Chamil U K
authors.initials: CU
authors.lastname: Samaranayaka
authors.affiliation: Department of Oral Sciences, School of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Rochelle
authors.initials: R
authors.lastname: Enright
authors.affiliation: Department of Oral Sciences, School of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Kyle T
authors.initials: KT
authors.lastname: Beggs
authors.affiliation: Department of Oral Sciences, School of Dentistry, University of Otago, Dunedin, New Zealand. Electronic address: brian.monk@otago.ac.nz.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Monk
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D027081:DNA Gyrase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D006868:Hydrolysis; D008958:Models, Molecular; D016963:Thermus thermophilus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D027081:DNA Gyrase
keywords: DNA gyrase; Drug screening; Gyrase-DNA ternary complex; Structure-directed drug discovery