The DNA end-binding protein Ku regulates silencing at the internal HML and HMR loci in Saccharomyces cerevisiae.
Heterochromatin resides near yeast telomeres and at the cryptic mating-type loci, HML and HMR, where it silences transcription of the alpha- and a-mating-type genes, respectively. Ku is a conserved DNA end-binding protein that binds telomeres and regulates silencing in yeast. The role of Ku in silencing is thought to be limited to telomeric silencing. Here, we tested whether Ku contributes to silencing at HML or HMR. Mutant analysis revealed that yKu70 and Sir1 act collectively to silence the mating-type genes at HML and HMR. In addition, loss of yKu70 function leads to expression of different reporter genes inserted at HMR. Quantitative chromatin-immunoprecipitation experiments revealed that yKu70 binds to HML and HMR and that binding of Ku to these internal loci is dependent on Sir4. The interaction between yKu70 and Sir4 was characterized further and found to be dependent on Sir2 but not on Sir1, Sir3, or yKu80. These observations reveal that, in addition to its ability to bind telomeric DNA ends and aid in the silencing of genes at telomeres, Ku binds to internal silent loci via protein-protein interactions and contributes to the efficient silencing of these loci.
Vandre
Catherine L
CL
Department of Cell and Developmental Biology, University of Illinois, Urbana, Illinois 61801, USA.
Kamakaka
Rohinton T
RT
Rivier
David H
DH
D047369:Chromatin Immunoprecipitation; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D049770:Genes, Mating Type, Fungal; D016133:Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism; D014158:Transcription, Genetic
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; C520769:YKU70 protein, S cerevisiae; C520770:YKU80 protein, S cerevisiae
Mol Cell Biol. 1991 Nov;11(11):5648-59
1922068
Yeast. 1994 Dec;10(13):1793-808
7747518
Nat Rev Genet. 2006 Oct;7(10):793-803
16983375
Curr Opin Cell Biol. 1997 Jun;9(3):383-7
9159071
Cell. 1990 Nov 16;63(4):751-62
2225075
EMBO Rep. 2001 Mar;2(3):197-202
11266360
Yeast. 1999 Jul;15(10B):963-72
10407276
J Biol Chem. 2004 Jan 2;279(1):86-94
14551211
Nat Struct Mol Biol. 2007 Apr;14(4):301-7
17351632
Nucleic Acids Res. 1993 Jul 11;21(14):3329-30
8341614
Curr Opin Cell Biol. 2002 Jun;14(3):377-83
12067662
Cell. 1989 Nov 17;59(4):637-47
2684414
Oncogene. 2002 Jan 21;21(4):512-21
11850776
Nature. 1997 Aug 28;388(6645):900-3
9278054
Annu Rev Genet. 2005;39:431-51
16285867
Genes Dev. 1993 Jul;7(7A):1146-59
8319907
Mol Biol Cell. 2001 Nov;12(11):3386-401
11694575
Cell. 1999 May 28;97(5):621-33
10367891
EMBO J. 2004 Mar 24;23(6):1301-12
15014445
EMBO Rep. 2001 Mar;2(3):203-10
11266361
Genes Dev. 1991 Apr;5(4):616-28
2010087
Curr Biol. 1998 May 21;8(11):657-60
9635193
Proc Natl Acad Sci U S A. 1979 Sep;76(9):4539-43
388445
Nature. 2001 Aug 9;412(6847):607-14
11493912
Annu Rev Biochem. 2007;76:75-100
17362198
Mol Cell. 2005 May 13;18(4):395-8
15893722
DNA Cell Biol. 2003 Feb;22(2):65-78
12713733
Mol Cell Biol. 1993 Jul;13(7):3919-28
8321199
Mol Biol Cell. 1999 Mar;10(3):567-80
10069804
Genes Dev. 1994 Oct 1;8(19):2257-69
7958893
Curr Opin Genet Dev. 2006 Apr;16(2):177-83
16503127
Yeast. 1995 Dec;11(16):1553-73
8720065
Methods Enzymol. 1991;194:3-21
2005794
Curr Biol. 1999 Oct 7;9(19):1123-6
10531008
Cell. 1989 Jun 2;57(5):725-37
2655930
Genetics. 1979 Dec;93(4):877-901
397913
Genetics. 1996 Dec;144(4):1425-36
8978031
Genetics. 2007 Dec;177(4):2541-6
18073447
J Cell Sci. 2008 Mar 1;121(Pt 5):590-600
18252799
Methods Enzymol. 1999;304:414-30
10372374
Science. 1998 May 1;280(5364):741-4
9563951
Biochim Biophys Acta. 2004 Mar 15;1677(1-3):120-8
15020053
Genes Dev. 2003 Oct 1;17(19):2347-50
14522942
J Cell Sci. 2005 Aug 1;118(Pt 15):3247-61
16014376
Genetics. 1999 Sep;153(1):13-23
10471696
Cell. 1985 May;41(1):41-8
3888409
Genetics. 2008 Oct;180(2):771-83
18716325
Genetics. 1999 Feb;151(2):521-9
9927448
Proc Natl Acad Sci U S A. 1997 Feb 4;94(3):867-72
9023348
Yeast. 1999 Aug;15(11):1141-9
10455237
BMC Mol Biol. 2006 Dec 22;7:48
17187679
Cell. 1987 Dec 4;51(5):721-32
3315231
Nat Rev Mol Cell Biol. 2006 Sep;7(9):657-66
16912715
DNA Repair (Amst). 2005 Nov 21;4(11):1215-26
15979949
Mol Cell Biol. 1988 Jan;8(1):210-25
3275867
Yeast. 1991 Apr;7(3):253-63
1882550
EMBO J. 1998 Mar 16;17(6):1819-28
9501103
Yeast. 1999 Oct;15(14):1541-53
10514571
Nucleic Acids Res. 2007;35(7):2302-10
17389650
Mol Cell Biol. 2008 Mar;28(6):1924-35
18195043
Mol Cell Biol. 1989 Nov;9(11):4621-30
2689860
Trends Genet. 1994 Nov;10(11):408-12
7809947
Genetics. 1979 Sep;93(1):13-35
16118901
Cell. 2004 Dec 29;119(7):955-67
15620354
Curr Genet. 1989 Oct;16(4):225-39
2697465
Annu Rev Cell Dev Biol. 1995;11:519-48
8689568
Annu Rev Biochem. 2003;72:481-516
12676793
Curr Biol. 1998 May 21;8(11):653-6
9635192