Tethered Sir3p nucleates silencing at telomeres and internal loci in Saccharomyces cerevisiae Journal Article
| Authors: | Lustig, A. J.; Liu, C.; Zhang, C.; Hanish, J. P. |
| Article Title: | Tethered Sir3p nucleates silencing at telomeres and internal loci in Saccharomyces cerevisiae |
| Abstract: | Rap1p binds to sites embedded within the Saccharomyces cerevisiae telomeric TG1-3 tract. Previous studies have led to the hypothesis that Rap1p may recruit Sir3p and Sir3p-associating factors to the telomere. To test this, we tethered Sir3p adjacent to the telomere via LexA binding sites in the rap1-17 mutant that truncates the Rap1p C-terminal 165 amino acids thought to contain sites for Sir3p association. Tethering of LexA-Sir3p adjacent to the telomere is sufficient to restore telomeric silencing, indicating that Sir3p can nucleate silencing at the telomere. Tethering of LexA-Sir3p or the LexA-Sir3p(N205) gain-of-function protein to a telomeric LexA site hyperrepresses an adjacent ADE2 gene in wild-type cells. Hence, Sir3p recruitment to the telomere is limiting in telomeric silencing. In addition, LexA-Str3p(N205) hyperrepresses telomeric silencing when tethered to a subtelomeric site 3.6 kb from the telomeric tract. This hyperrepression is dependent on the C terminus of Rap1p, suggesting that subtelomeric LexA- Sir3p(N205) can interact with Rap1p-associated factors at the telomere. We also demonstrate that LexA-Sir3p or LexA-Sir3p(N205) tethered in cis with a short tract of telomeric TG1-3 sequences is sufficient to confer silencing at an internal chromosomal position. Internal silencing is enhanced in rap1- 17 strains. We propose that sequestration of silencing factors at the telomere limits the efficiency of internal silencing. |
| Keywords: | gene cluster; nonhuman; dna replication; telomere; cell cycle s phase; gene expression; gtp-binding proteins; gene locus; genotype; transcription, genetic; bacterial proteins; amino terminal sequence; recombinant fusion proteins; serine endopeptidases; saccharomyces cerevisiae; gene repression; plasmids; binding site; dna sequence; binding sites; trans-activators; mutagenesis; chromosomes, fungal; fungal proteins; suppression, genetic; priority journal; article; silent information regulator proteins, saccharomyces cerevisiae; models, structural; rap gtp-binding proteins; silencer gene |
| Journal Title: | Molecular and Cellular Biology |
| Volume: | 16 |
| Issue: | 5 |
| ISSN: | 0270-7306 |
| Publisher: | American Society for Microbiology |
| Date Published: | 1996-05-01 |
| Start Page: | 2483 |
| End Page: | 2495 |
| Language: | English |
| PUBMED: | 8628316 |
| PROVIDER: | scopus |
| PMCID: | PMC231237 |
| DOI: | 10.1128/MCB.16.5.2483 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 22 November 2017 -- Source: Scopus |
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