title: Complex activities of the human Bloom's syndrome helicase are encoded in a core region comprising the RecA and Zn-binding domains.
abstract: Bloom's syndrome DNA helicase (BLM), a member of the RecQ family, is a key player in homologous recombination (HR)-based error-free DNA repair processes. During HR, BLM exerts various biochemical activities including single-stranded (ss) DNA translocation, separation and annealing of complementary DNA strands, disruption of complex DNA structures (e.g. displacement loops) and contributes to quality control of HR via clearance of Rad51 nucleoprotein filaments. We performed a quantitative mechanistic analysis of truncated BLM constructs that are shorter than the previously identified minimal functional module. Surprisingly, we found that a BLM construct comprising only the two conserved RecA domains and the Zn(2+)-binding domain (residues 642-1077) can efficiently perform all mentioned HR-related activities. The results demonstrate that the Zn(2+)-binding domain is necessary for functional interaction with DNA. We show that the extensions of this core, including the winged-helix domain and the strand separation hairpin identified therein in other RecQ-family helicases, are not required for mechanochemical activity per se and may instead play modulatory roles and mediate protein-protein interactions.
authors.affiliation: Department of Biochemistry, ELTE-MTA Momentum Motor Enzymology Research Group, Eötvös University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary.
authors.forename: Máté
authors.initials: M
authors.lastname: Gyimesi
authors.forename: Gábor M
authors.initials: GM
authors.lastname: Harami
authors.forename: Kata
authors.initials: K
authors.lastname: Sarlós
authors.forename: Eszter
authors.initials: E
authors.lastname: Hazai
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bikádi
authors.forename: Mihály
authors.initials: M
authors.lastname: Kovács
mesh_terms: D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D051135:Rad51 Recombinase / Q000378:metabolism; D011938:Rec A Recombinases / Q000737:chemistry; D053484:RecQ Helicases / Q000737:chemistry* / Q000378:metabolism; D015032:Zinc / Q000737:chemistry
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; C097151:Bloom syndrome protein; D053484:RecQ Helicases; D015032:Zinc