title: The reverse gyrase from Pyrobaculum calidifontis, a novel extremely thermophilic DNA topoisomerase endowed with DNA unwinding and annealing activities.
abstract: Reverse gyrase is a DNA topoisomerase specific for hyperthermophilic bacteria and archaea. It catalyzes the peculiar ATP-dependent DNA-positive supercoiling reaction and might be involved in the physiological adaptation to high growth temperature. Reverse gyrase comprises an N-terminal ATPase and a C-terminal topoisomerase domain, which cooperate in enzyme activity, but details of its mechanism of action are still not clear. We present here a functional characterization of PcalRG, a novel reverse gyrase from the archaeon Pyrobaculum calidifontis. PcalRG is the most robust and processive reverse gyrase known to date; it is active over a wide range of conditions, including temperature, ionic strength, and ATP concentration. Moreover, it holds a strong ATP-inhibited DNA cleavage activity. Most important, PcalRG is able to induce ATP-dependent unwinding of synthetic Holliday junctions and ATP-stimulated annealing of unconstrained single-stranded oligonucleotides. Combined DNA unwinding and annealing activities are typical of certain helicases, but until now were shown for no other reverse gyrase. Our results suggest for the first time that a reverse gyrase shares not only structural but also functional features with evolutionary conserved helicase-topoisomerase complexes involved in genome stability.
authors.affiliation: From the Institute of Protein Biochemistry and.
authors.forename: Anmbreen
authors.initials: A
authors.lastname: Jamroze
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Perugino
authors.forename: Anna
authors.initials: A
authors.lastname: Valenti
authors.forename: Naeem
authors.initials: N
authors.lastname: Rashid
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Muhammad
authors.initials: M
authors.lastname: Akhtar
authors.forename: Maria
authors.initials: M
authors.lastname: Ciaramella
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019641:DNA, Archaeal / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D042822:Genomic Instability / Q000502:physiology; D041543:Pyrobaculum / Q000201:enzymology* / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D000255:Adenosine Triphosphate; C041813:DNA reverse gyrase; D004264:DNA Topoisomerases, Type I
keywords: DNA Enzymes; DNA Helicase; DNA Recombination; DNA Repair; DNA Topoisomerase; Holliday Junction; Thermophiles