title: DNA Topoisomerases.
abstract: DNA topoisomerases are enzymes that control the topology of DNA in all cells. There are two types, I and II, classified according to whether they make transient single- or double-stranded breaks in DNA. Their reactions generally involve the passage of a single- or double-strand segment of DNA through this transient break, stabilized by DNA-protein covalent bonds. All topoisomerases can relax DNA, but DNA gyrase, present in all bacteria, can also introduce supercoils into DNA. Because of their essentiality in all cells and the fact that their reactions proceed via DNA breaks, topoisomerases have become important drug targets; the bacterial enzymes are key targets for antibacterial agents. This article discusses the structure and mechanism of topoisomerases and their roles in the bacterial cell. Targeting of the bacterial topoisomerases by inhibitors, including antibiotics in clinical use, is also discussed.
authors.forename: Natassja G
authors.initials: NG
authors.lastname: Bush
authors.forename: Katherine
authors.initials: K
authors.lastname: Evans-Roberts
authors.forename: Anthony
authors.initials: A
authors.lastname: Maxwell
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000201:enzymology* / Q000378:metabolism; D001430:Bacteriocins / Q000494:pharmacology; D027081:DNA Gyrase / Q000737:chemistry / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000737:chemistry / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000737:chemistry / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry; D004278:DNA, Superhelical; D008958:Models, Molecular; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; C020411:microcin; D004264:DNA Topoisomerases, Type I; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II