Mcm10 is required for the maintenance of transcriptional silencing in Saccharomyces cerevisiae.
Mcm10 is an essential protein that participates in both the initiation and the elongation of DNA replication. In this study we demonstrate a role for Mcm10 in the maintenance of heterochromatic silencing at telomeres and HM loci of budding yeast. Two mcm10 mutants drastically reduce silencing of both URA3 and ADE2 reporter genes integrated into these silent loci. When exposed to alpha-factor, mcm10 mutant cells display a "shmoo-cluster" phenotype associated with a defect in the maintenance of silencing. In addition, when combined with a defect in the establishment of silent chromatin, mcm10 mutants demonstrate a synergistic defect in HML silencing. Consistent with a direct silencing function, Mcm10p shows a two-hybrid interaction with Sir2p and Sir3p that is destroyed by the mcm10-1 mutation and dependent on the C-terminal 108 amino acids. Tethering GBD-MCM10 to a defective HMR-E silencer is not sufficient to restore silencing. Furthermore, mutations in MCM10 inhibit the ability of GBD-SIR3 to restore silencing when tethered to a defective HMR-E. Suppressor mutations in MCM2, which suppress the temperature sensitivity of mcm10-1, fail to overcome the mcm10-1 silencing defect, suggesting that MCM10's role in transcriptional silencing may be separate from its essential functions in DNA replication.
Liachko
Ivan
I
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Tye
Bik K
BK
D018797:Cell Cycle Proteins / Q000235:genetics* / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D006655:Histone Deacetylases / Q000378:metabolism; D000072235:Mating Factor; D064110:Minichromosome Maintenance Proteins; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000502:physiology; D037941:Silencer Elements, Transcriptional / Q000235:genetics*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000378:metabolism; D056565:Sirtuin 2; D037761:Sirtuins / Q000378:metabolism; D016615:Telomere / Q000235:genetics; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; C076365:MCM10 protein, S cerevisiae; D010455:Peptides; C084122:SIR3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D000072235:Mating Factor; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2; D037761:Sirtuins; D006655:Histone Deacetylases; D064110:Minichromosome Maintenance Proteins