title: Unveiling two distinct ribonuclease activities and a topoisomerase activity in a site-specific DNA recombinase.
abstract: The site-specific DNA recombinase Flp shows two types of RNA cleavage activities on hybrid DNA-RNA substrates. One targets the phosphodiester position involved in DNA recombination and follows a related mechanistic path. In this two-step reaction, first-strand scission is mediated by a nucleophilic attack of the scissile phosphodiester bond by the active site tyrosine of Flp. The resultant 3'-O-phosphoryl tyrosine bond is then attacked by the adjacent 2'-hydroxyl group. The second activity targets the immediately adjacent phosphodiester bond to the 3' side using a distinct mechanism. In this reaction, the vicinal 2'-hydroxyl directly attacks the phosphate group in a manner that is reminiscent of the pancreatic RNase mechanism. The Flp protein can also be shown to possess a topoisomerase-like activity.
authors.affiliation: Department of Microbiology, University of Texas at Austin 78712, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Xu
authors.forename: I
authors.initials: I
authors.lastname: Grainge
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.forename: R M
authors.initials: RM
authors.lastname: Harshey
authors.forename: M
authors.initials: M
authors.lastname: Jayaram
mesh_terms: D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D012331:RNA, Fungal / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D004254:DNA Nucleotidyltransferases; C045119:FLP recombinase; D012260:Ribonucleases; D004264:DNA Topoisomerases, Type I