title: Human RECQ5beta helicase promotes strand exchange on synthetic DNA structures resembling a stalled replication fork.
abstract: The role of the human RECQ5beta helicase in the maintenance of genomic stability remains elusive. Here we show that RECQ5beta promotes strand exchange between arms of synthetic forked DNA structures resembling a stalled replication fork in a reaction dependent on ATP hydrolysis. BLM and WRN can also promote strand exchange on these structures. However, in the presence of human replication protein A (hRPA), the action of these RecQ-type helicases is strongly biased towards unwinding of the parental duplex, an effect not seen with RECQ5beta. A domain within the non-conserved portion of RECQ5beta is identified as being important for its ability to unwind the lagging-strand arm and to promote strand exchange on hRPA-coated forked structures. We also show that RECQ5beta associates with DNA replication factories in S phase nuclei and persists at the sites of stalled replication forks after exposure of cells to UV irradiation. Moreover, RECQ5beta is found to physically interact with the polymerase processivity factor proliferating cell nuclear antigen in vitro and in vivo. Collectively, these findings suggest that RECQ5beta may promote regression of stalled replication forks to facilitate the bypass of replication-blocking lesions by template-switching. Loss of such activity could explain the elevated level of mitotic crossovers observed in RECQ5beta-deficient cells.
authors.affiliation: Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Radhakrishnan
authors.initials: R
authors.lastname: Kanagaraj
authors.forename: Nurten
authors.initials: N
authors.lastname: Saydam
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Garcia
authors.forename: Lu
authors.initials: L
authors.lastname: Zheng
authors.forename: Pavel
authors.initials: P
authors.lastname: Janscak
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D002460:Cell Line; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication; D006367:HeLa Cells; D006801:Humans; D009841:Oligonucleotides / Q000737:chemistry; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017434:Protein Structure, Tertiary; D053484:RecQ Helicases / Q000737:chemistry / Q000378:metabolism*; D051716:Replication Protein A / Q000378:metabolism; D013698:Templates, Genetic
chemical_list: D009841:Oligonucleotides; D018809:Proliferating Cell Nuclear Antigen; C506732:RECQL5 protein, human; D051716:Replication Protein A; D004247:DNA; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases