title: Rap1 binds single-stranded DNA at telomeric double- and single-stranded junctions and competes with Cdc13 protein.
abstract: The ends of eukaryotic chromosomes are protected by specialized telomere chromatin structures. Rap1 and Cdc13 are essential for the formation of functional telomere chromatin in budding yeast by binding to the double-stranded part and the single-stranded 3' overhang, respectively. We analyzed the binding properties of Saccharomyces castellii Rap1 and Cdc13 to partially single-stranded oligonucleotides, mimicking the junction of the double- and single-stranded DNA (ds-ss junction) at telomeres. We determined the optimal and the minimal DNA setup for a simultaneous binding of Rap1 and Cdc13 at the ds-ss junction. Remarkably, Rap1 is able to bind to a partially single-stranded binding site spanning the ds-ss junction. The binding over the ds-ss junction is anchored in a single double-stranded hemi-site and is stabilized by a sequence-independent interaction of Rap1 with the single-stranded 3' overhang. Thus, Rap1 is able to switch between a sequence-specific and a nonspecific binding mode of one hemi-site. At a ds-ss junction configuration where the two binding sites partially overlap, Rap1 and Cdc13 are competing for the binding. These results shed light on the end protection mechanisms and suggest that Rap1 and Cdc13 act together to ensure the protection of both the 3' and the 5' DNA ends at telomeres.
authors.affiliation: Department of Biology, Genetics Group, Lund University, SE-223 62 Lund, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gustafsson
authors.forename: Jenny
authors.initials: J
authors.lastname: Rhodin Edsö
authors.forename: Marita
authors.initials: M
authors.lastname: Cohn
mesh_terms: D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D012440:Saccharomyces / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D004277:DNA, Single-Stranded; D005656:Fungal Proteins; D034501:Telomere-Binding Proteins; D020827:rap1 GTP-Binding Proteins
references.citation: Science. 1999 Oct 1;286(5437):117-20
references.pmid: 10506558
references.citation: Curr Genet. 1998 Feb;33(2):83-91
references.pmid: 9506895
references.citation: Genome Integr. 2011 Jan 14;2(1):2
references.pmid: 21235754
references.citation: Science. 1995 Jul 21;269(5222):396-400
references.pmid: 7618104
references.citation: Yeast. 2002 Feb;19(3):241-56
references.pmid: 11816032
references.citation: Science. 1996 Oct 11;274(5285):249-52
references.pmid: 8824190
references.citation: J Mol Biol. 2006 Jan 20;355(3):335-46
references.pmid: 16318854
references.citation: Science. 2002 Aug 9;297(5583):1023-6
references.pmid: 12169735
references.citation: Mol Cell Biol. 1995 Nov;15(11):6128-38
references.pmid: 7565765
references.citation: Mol Cell Biol. 2004 Dec;24(24):10857-67
references.pmid: 15572688
references.citation: J Mol Biol. 2004 May 14;338(5):877-93
references.pmid: 15111054
references.citation: Cell. 1997 Mar 7;88(5):657-66
references.pmid: 9054505
references.citation: Cell. 2004 Apr 30;117(3):323-35
references.pmid: 15109493
references.citation: EMBO J. 2001 Oct 1;20(19):5532-40
references.pmid: 11574485
references.citation: Cell. 1996 Apr 5;85(1):125-36
references.pmid: 8620531
references.citation: J Mol Biol. 1993 May 20;231(2):293-310
references.pmid: 8510148
references.citation: Mol Biol Cell. 2003 Feb;14(2):556-70
references.pmid: 12589054
references.citation: Nat Genet. 2001 Aug;28(4):327-34
references.pmid: 11455386
references.citation: J Mol Biol. 2000 Nov 10;303(5):693-707
references.pmid: 11061969
references.citation: Nucleic Acids Res. 2000 Jun 15;28(12):2292-301
references.pmid: 10871358
references.citation: J Biol Chem. 2010 Nov 12;285(46):35814-24
references.pmid: 20826803
references.citation: Nature. 2003 Oct 16;425(6959):737-41
references.pmid: 14562106
references.citation: Genes Dev. 2000 Jul 15;14(14):1777-88
references.pmid: 10898792
references.citation: Nat Struct Mol Biol. 2007 Mar;14(3):208-14
references.pmid: 17293872
references.citation: J Biol Chem. 2005 Dec 30;280(52):42568-72
references.pmid: 16204246
references.citation: Genes Dev. 1994 Oct 1;8(19):2257-69
references.pmid: 7958893
references.citation: Biochem Biophys Res Commun. 2005 Mar 4;328(1):49-56
references.pmid: 15670749
references.citation: Mol Biol Cell. 1997 Nov;8(11):2145-55
references.pmid: 9362059
references.citation: Science. 1997 Feb 14;275(5302):986-90
references.pmid: 9020083
references.citation: EMBO J. 2001 Nov 1;20(21):6127-39
references.pmid: 11689452
references.citation: J Biol Chem. 2006 Dec 8;281(49):37486-95
references.pmid: 17052985
references.citation: Cell. 2001 Feb 9;104(3):387-96
references.pmid: 11239396
references.citation: Cell. 1993 Jan 15;72(1):51-60
references.pmid: 8422682
references.citation: EMBO J. 2009 Aug 19;28(16):2309-22
references.pmid: 19629031
references.citation: Proc Natl Acad Sci U S A. 1996 Nov 26;93(24):13760-5
references.pmid: 8943008
references.citation: Genome. 1989;31(2):553-60
references.pmid: 2698831
references.citation: Cell. 1996 May 3;85(3):423-33
references.pmid: 8616897
references.citation: Cell. 1987 Dec 4;51(5):721-32
references.pmid: 3315231
references.citation: Mol Cell. 2005 Apr 1;18(1):131-8
references.pmid: 15808515
references.citation: Cell. 1999 May 14;97(4):503-14
references.pmid: 10338214
references.citation: Genes Dev. 1993 Jul;7(7B):1364-76
references.pmid: 8330740
references.citation: J Mol Biol. 2004 Apr 23;338(2):241-55
references.pmid: 15066429