title: A two-subunit type I DNA topoisomerase (reverse gyrase) from an extreme hyperthermophile.
abstract: A recently described reverse gyrase from the hyperthermophilic methanogen Methanopyrus kandleri is the only known example of a heterodimeric type I topoisomerase. The enzyme is made up of a 42-kDa subunit which covalently interacts with DNA (RgyA) and a 138-kDa subunit which binds ATP (RgyB). We have now cloned and sequenced the genes for both subunits of this enzyme. Surprisingly, the universally conserved type I topoisomerase domain [Lima, C. D., Wang, J. C. & Mondragon, A. (1994) Nature (London) 367, 138-146] which has been found as a contiguous polypeptide in the prokaryotes and eukaryotes is shared between the protomers. The subdomain with the active-site tyrosine is entirely within RgyA, whereas the subdomain implicated in noncovalent binding of the cleaved DNA strand is contained entirely in RgyB. The appearance of this unique structure in a highly conserved enzyme family supports the hypothesis that the methanogens branched from other prokaryotes and eukaryotes very early in evolution.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: R
authors.initials: R
authors.lastname: Krah
authors.forename: S A
authors.initials: SA
authors.lastname: Kozyavkin
authors.forename: A I
authors.initials: AI
authors.lastname: Slesarev
authors.forename: M
authors.initials: M
authors.lastname: Gellert
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004264:DNA Topoisomerases, Type I / Q000737:chemistry*; D004250:DNA Topoisomerases, Type II / Q000737:chemistry*; D019605:Euryarchaeota / Q000201:enzymology*; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D046911:Macromolecular Substances; C041813:DNA reverse gyrase; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II