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A two-subunit type I DNA topoisomerase (reverse gyrase) from an extreme hyperthermophile.

1996; National Academy of Sciences; Volume: 93; Issue: 1 Linguagem: Inglês

10.1073/pnas.93.1.106

1091-6490

Regis Krah, Sergei A. Kozyavkin, Alexeï Slesarev, Martin Gellert,

Antibiotic Resistance in Bacteria

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.