title: An essential DNA strand-exchange activity is conserved in the divergent N-termini of BLM orthologs.
abstract: The gene mutated in Bloom's syndrome, BLM, encodes a member of the RecQ family of DNA helicases that is needed to suppress genome instability and cancer predisposition. BLM is highly conserved and all BLM orthologs, including budding yeast Sgs1, have a large N-terminus that binds Top3-Rmi1 but has no known catalytic activity. In this study, we describe a sub-domain of the Sgs1 N-terminus that shows in vitro single-strand DNA (ssDNA) binding, ssDNA annealing and strand-exchange (SE) activities. These activities are conserved in the human and Drosophila orthologs. SE between duplex DNA and homologous ssDNA requires no cofactors and is inhibited by a single mismatched base pair. The SE domain of Sgs1 is required in vivo for the suppression of hyper-recombination, suppression of synthetic lethality and heteroduplex rejection. The top3Delta slow-growth phenotype is also SE dependent. Surprisingly, the highly divergent human SE domain functions in yeast. This work identifies SE as a new molecular function of BLM/Sgs1, and we propose that at least one role of SE is to mediate the strand-passage events catalysed by Top3-Rmi1.
authors.affiliation: Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, USA.
authors.forename: Chi-Fu
authors.initials: CF
authors.lastname: Chen
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Brill
mesh_terms: D000483:Alleles; D000818:Animals; D001816:Bloom Syndrome / Q000235:genetics*; D017124:Conserved Sequence; D004247:DNA / Q000235:genetics; D004265:DNA Helicases / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics; D004331:Drosophila melanogaster; D006801:Humans; D007700:Kinetics; D009154:Mutation; D017434:Protein Structure, Tertiary; D053484:RecQ Helicases / Q000235:genetics* / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D004277:DNA, Single-Stranded; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; C097151:Bloom syndrome protein; C090472:SGS1 protein, S cerevisiae; D004265:DNA Helicases; D053484:RecQ Helicases
references.citation: Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):11108-13
references.pmid: 11553789
references.citation: J Biol Chem. 1998 Oct 16;273(42):27587-92
references.pmid: 9765292
references.citation: Crit Rev Biochem Mol Biol. 2004 Mar-Apr;39(2):79-97
references.pmid: 15217989
references.citation: Nat Rev Cancer. 2009 Sep;9(9):644-54
references.pmid: 19657341
references.citation: J Biol Chem. 2006 Aug 11;281(32):22839-46
references.pmid: 16766518
references.citation: Nucleic Acids Res. 2006 May 02;34(8):2269-79
references.pmid: 16670433
references.citation: Genetics. 2005 Feb;169(2):563-74
references.pmid: 15489516
references.citation: Nature. 2003 Dec 18;426(6968):870-4
references.pmid: 14685245
references.citation: J Biol Chem. 2000 Mar 31;275(13):9636-44
references.pmid: 10734115
references.citation: J Biol Chem. 2001 Jun 1;276(22):19375-81
references.pmid: 11278509
references.citation: Proc Natl Acad Sci U S A. 1974 Nov;71(11):4508-12
references.pmid: 4140506
references.citation: Nucleic Acids Res. 2005 Jul 15;33(12):3932-41
references.pmid: 16024743
references.citation: Hum Mutat. 2007 Aug;28(8):743-53
references.pmid: 17407155
references.citation: J Biol Chem. 2009 Sep 25;284(39):26349-59
references.pmid: 19632996
references.citation: Nature. 1996 Oct 24;383(6602):678-9
references.pmid: 8878475
references.citation: EMBO J. 2003 Oct 1;22(19):4910-21
references.pmid: 14517231
references.citation: Cell. 1989 Jul 28;58(2):409-19
references.pmid: 2546682
references.citation: J Biol Chem. 2005 Jul 29;280(30):28072-84
references.pmid: 15899892
references.citation: EMBO J. 2004 Jul 21;23(14):2882-91
references.pmid: 15241474
references.citation: Mol Genet Genomics. 2001 Jul;265(5):837-50
references.pmid: 11523801
references.citation: J Biol Chem. 2009 Nov 6;284(45):30845-52
references.pmid: 19759018
references.citation: EMBO J. 2009 Mar 4;28(5):568-77
references.pmid: 19177149
references.citation: Genetics. 2008 Jul;179(3):1157-67
references.pmid: 18562672
references.citation: Genes Genet Syst. 2000 Dec;75(6):319-26
references.pmid: 11280006
references.citation: DNA Repair (Amst). 2006 Feb 3;5(2):172-80
references.pmid: 16214424
references.citation: BMC Mol Biol. 2006 Jan 13;7:1
references.pmid: 16412221
references.citation: DNA Repair (Amst). 2008 Apr 2;7(4):558-71
references.pmid: 18272435
references.citation: J Biol Chem. 2005 Jun 17;280(24):23397-407
references.pmid: 15845538
references.citation: Mol Cell. 2005 Dec 9;20(5):783-92
references.pmid: 16337601
references.citation: Structure. 2005 Aug;13(8):1173-82
references.pmid: 16084389
references.citation: Curr Biol. 2003 Nov 11;13(22):1954-62
references.pmid: 14614820
references.citation: J Biol Chem. 2000 Sep 1;275(35):26898-905
references.pmid: 10862619
references.citation: EMBO J. 2009 Apr 8;28(7):915-25
references.pmid: 19214189
references.citation: J Biol Chem. 2009 Nov 6;284(45):30737-41
references.pmid: 19726668
references.citation: Proc Natl Acad Sci U S A. 2004 Jun 22;101(25):9315-20
references.pmid: 15199178
references.citation: Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):16906-11
references.pmid: 18971343
references.citation: Mol Cell Biol. 1994 Dec;14(12):8391-8
references.pmid: 7969174
references.citation: EMBO J. 2005 Jul 20;24(14):2679-87
references.pmid: 15990871
references.citation: Cell. 2008 Sep 19;134(6):981-94
references.pmid: 18805091
references.citation: Mol Cell Biol. 2005 May;25(9):3431-42
references.pmid: 15831450
references.citation: Proc Natl Acad Sci U S A. 2006 Jul 25;103(30):11118-23
references.pmid: 16849422
references.citation: Genetics. 2000 Mar;154(3):1101-14
references.pmid: 10757756
references.citation: Biochemistry. 2008 Sep 30;47(39):10247-54
references.pmid: 18771289
references.citation: PLoS Biol. 2007 Feb;5(2):e20
references.pmid: 17227144
references.citation: Mol Cell Biol. 2005 Jun;25(11):4476-87
references.pmid: 15899853
references.citation: Science. 2003 Jan 10;299(5604):265-7
references.pmid: 12522255
references.citation: Mol Cell Biol. 2006 Jun;26(11):4086-94
references.pmid: 16705162
references.citation: Nucleic Acids Res. 2007;35(4):1367-76
references.pmid: 17272294
references.citation: Mol Cell Biol. 2003 May;23(10):3527-35
references.pmid: 12724411
references.citation: Nature. 2008 Oct 9;455(7214):770-4
references.pmid: 18806779
references.citation: J Biol Chem. 2001 Mar 23;276(12):8848-55
references.pmid: 11124263
references.citation: J Biol Chem. 2007 Sep 28;282(39):28971-28979
references.pmid: 17693398
references.citation: Genetics. 2001 Jan;157(1):103-18
references.pmid: 11139495
references.citation: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6504-8
references.pmid: 10823897
references.citation: Nucleic Acids Res. 2005 Oct 31;33(19):6251-7
references.pmid: 16260474