title: Physical and functional interactions of Caenorhabditis elegans WRN-1 helicase with RPA-1.
abstract: The Caenorhabditis elegans Werner syndrome protein, WRN-1, a member of the RecQ helicase family, has a 3'-5' DNA helicase activity. Worms with defective wrn-1 exhibit premature aging phenotypes and an increased level of genome instability. In response to DNA damage, WRN-1 participates in the initial stages of checkpoint activation in concert with C. elegans replication protein A (RPA-1). WRN-1 helicase is stimulated by RPA-1 on long DNA duplex substrates. However, the mechanism by which RPA-1 stimulates DNA unwinding and the function of the WRN-1-RPA-1 interaction are not clearly understood. We have found that WRN-1 physically interacts with two RPA-1 subunits, CeRPA73 and CeRPA32; however, full-length WRN-1 helicase activity is stimulated by only the CeRPA73 subunit, while the WRN-1(162-1056) fragment that harbors the helicase activity requires both the CeRPA73 and CeRPA32 subunits for the stimulation. We also found that the CeRPA73(1-464) fragment can stimulate WRN-1 helicase activity and that residues 335-464 of CeRPA73 are important for physical interaction with WRN-1. Because CeRPA73 and the CeRPA73(1-464) fragment are able to bind single-stranded DNA (ssDNA), the stimulation of WRN-1 helicase by RPA-1 is most likely due to the ssDNA binding activity of CeRPA73 and the direct interaction of WRN-1 and CeRPA73.
authors.affiliation: Department of Life Sciences, University of Ulsan, Ulsan 680-749, Korea.
authors.forename: Moonjung
authors.initials: M
authors.lastname: Hyun
authors.forename: Sojin
authors.initials: S
authors.lastname: Park
authors.forename: Eunsun
authors.initials: E
authors.lastname: Kim
authors.forename: Do-Hyung
authors.initials: DH
authors.lastname: Kim
authors.forename: Se-Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Hyeon-Sook
authors.initials: HS
authors.lastname: Koo
authors.forename: Yeon-Soo
authors.initials: YS
authors.lastname: Seo
authors.forename: Byungchan
authors.initials: B
authors.lastname: Ahn
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004265:DNA Helicases / Q000737:chemistry*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D005838:Genotype; D006801:Humans; D010641:Phenotype; D053484:RecQ Helicases / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D051716:Replication Protein A / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D004277:DNA, Single-Stranded; D011994:Recombinant Proteins; D051716:Replication Protein A; D004247:DNA; D004265:DNA Helicases; D053484:RecQ Helicases; C488009:WRN-1 protein, C elegans