title: Reverse gyrase recruitment to DNA after UV light irradiation in Sulfolobus solfataricus.
abstract: Induction of DNA damage triggers a complex biological response concerning not only repair systems but also virtually every cell function. DNA topoisomerases regulate the level of DNA supercoiling in all DNA transactions. Reverse gyrase is a peculiar DNA topoisomerase, specific to hyperthermophilic microorganisms, which contains a helicase and a topoisomerase IA domain that has the unique ability to introduce positive supercoiling into DNA molecules. We show here that reverse gyrase of the archaean Sulfolobus solfataricus is mobilized to DNA in vivo after UV irradiation. The enzyme, either purified or in cell extracts, forms stable covalent complexes with UV-damaged DNA in vitro. We also show that the reverse gyrase translocation to DNA in vivo and the stabilization of covalent complexes in vitro are specific effects of UV light irradiation and do not occur with the intercalating agent actinomycin D. Our results suggest that reverse gyrase might participate, directly or indirectly, in the cell response to UV light-induced DNA damage. This is the first direct evidence of the recruitment of a topoisomerase IA enzyme to DNA after the induction of DNA damage. The interaction between helicase and topoisomerase activities has been previously proposed to facilitate aspects of DNA replication or recombination in both Bacteria and Eukarya. Our results suggest a general role of the association of such activities in maintaining genome integrity and a mutual effect of DNA topology and repair.
authors.affiliation: Institute of Protein Biochemistry, Consiglio Nazionale delle Ricerche, Via P. Castellino 111, 80131 Naples, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Napoli
authors.forename: Anna
authors.initials: A
authors.lastname: Valenti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Salerno
authors.forename: Marc
authors.initials: M
authors.lastname: Nadal
authors.forename: Florence
authors.initials: F
authors.lastname: Garnier
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Maria
authors.initials: M
authors.lastname: Ciaramella
mesh_terms: D004249:DNA Damage; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D016944:Sulfolobus / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D059004:Topoisomerase I Inhibitors; D014466:Ultraviolet Rays
chemical_list: D004269:DNA, Bacterial; D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D059004:Topoisomerase I Inhibitors; D003609:Dactinomycin; C041813:DNA reverse gyrase; D004264:DNA Topoisomerases, Type I