title: The Bloom's syndrome helicase promotes the annealing of complementary single-stranded DNA.
abstract: The product of the gene mutated in Bloom's syndrome, BLM, is a 3'-5' DNA helicase belonging to the highly conserved RecQ family. In addition to a conventional DNA strand separation activity, BLM catalyzes both the disruption of non-B-form DNA, such as G-quadruplexes, and the branch migration of Holliday junctions. Here, we have characterized a new activity for BLM: the promotion of single-stranded DNA (ssDNA) annealing. This activity does not require Mg(2+), is inhibited by ssDNA binding proteins and ATP, and is dependent on DNA length. Through analysis of various truncation mutants of BLM, we show that the C-terminal domain is essential for strand annealing and identify a 60 amino acid stretch of this domain as being important for both ssDNA binding and strand annealing. We present a model in which the ssDNA annealing activity of BLM facilitates its role in the processing of DNA intermediates that arise during repair of damaged replication forks.
authors: Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital Oxford OX3 9DS, UK.
authors: Chit Fang
authors: CF
authors: Cheok
authors: Leonard
authors: L
authors: Wu
authors: Patrick L
authors: PL
authors: Garcia
authors: Pavel
authors: P
authors: Janscak
authors: Ian D
authors: ID
authors: Hickson
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D008957:Models, Genetic; D017434:Protein Structure, Tertiary; D053484:RecQ Helicases
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases