title: DNA transport by a type II topoisomerase: direct evidence for a two-gate mechanism.
abstract: Recent biochemical and crystallographic results suggest that a type II DNA topoisomerase acts as an ATP-modulated clamp with two sets of jaws at opposite ends: a DNA-bound enzyme can admit a second DNA through one set of jaws; upon binding ATP, this DNA is passed through an enzyme-mediated opening in the first DNA and expelled from the enzyme through the other set of jaws. Experiments based on the introduction of reversible disulfide links across one dimer interface of yeast DNA topoisomerase II have confirmed this mechanism. The second DNA is found to enter the enzyme through the gate formed by the N-terminal parts of the enzyme and leave it through the gate close to the C termini.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: J
authors.initials: J
authors.lastname: Roca
authors.forename: J M
authors.initials: JM
authors.lastname: Berger
authors.forename: S C
authors.initials: SC
authors.lastname: Harrison
authors.forename: J C
authors.initials: JC
authors.lastname: Wang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D001665:Binding Sites; D003196:Computer Graphics; D003198:Computer Simulation; D003432:Cross-Linking Reagents; D004250:DNA Topoisomerases, Type II / Q000737:chemistry* / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010957:Plasmids; D017354:Point Mutation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology
chemical_list: D003432:Cross-Linking Reagents; D004277:DNA, Single-Stranded; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D004250:DNA Topoisomerases, Type II