SIR1/YKR101W Summary Help

SIR1 BASIC INFORMATION

Standard Name SIR1 1
Systematic Name YKR101W
Feature Type ORF, Verified
Description Protein involved in repression of transcription at the silent mating-type loci HML and HMR; recruitment to silent chromatin requires interactions with Orc1p and with Sir4p, through a common Sir1p domain; binds to centromeric chromatin (2, 3, 4 and see Summary Paragraph)
Name Description Silent Information Regulator 1
GO Annotations All SIR1 GO evidence and references
    View Computational GO annotations for SIR1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Mutant Phenotype All SIR1 Phenotype details and references
Classical genetics
null
overexpression
reduction of function
Large-scale survey
null
overexpression
Interactions SIR1 All interactions details and references
108 total interaction(s) for 55 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 7
  • Affinity Capture-RNA: 1
  • Affinity Capture-Western: 7
  • Co-crystal Structure: 2
  • Co-fractionation: 1
  • Co-localization: 5
  • PCA: 1
  • Reconstituted Complex: 3
  • Two-hybrid: 12
Genetic Interactions
  • Dosage Rescue: 16
  • Phenotypic Enhancement: 34
  • Phenotypic Suppression: 3
  • Synthetic Growth Defect: 8
  • Synthetic Rescue: 8
Sequence Information
ChrXI:640178 to 642142 | ORF Map | GBrowse
Gbrowse
Genetic position: 84 cM
Last Update Coordinates: 2009-02-20 | Sequence: 2009-02-20
Subfeature details
Relative
Coordinates		 Chromosomal
Coordinates		 Most Recent Updates
Coordinates Sequence
CDS 1..1965 640178..642142 2009-02-20 2009-02-20
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | UniProtKB
Primary SGDIDS000001809

SIR1 RESOURCES

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  • Functional Analysis

Click on histogram for expression summary
Expression Summary histogram

ADDITIONAL INFORMATION for SIR1

SUMMARY PARAGRAPH for SIR1

SIR1 is one of four Silent Information Regulator genes in yeast. It encodes a nuclear protein that helps silence transcription of the cryptic mating type loci HML and HMR (1, 2, 5). Unlike repressors that act by binding to promoters, the Sir proteins help repress transcription by creating a silent chromatin stucture in a gene- and promoter-independent manner (6, 7). The Sir proteins do not bind DNA directly, but rather seem to act via histones and other DNA binding proteins (6, 8, 9). The exact means by which the Sir proteins create a silenced domain is unknown.

Silencing at HML and HMR depends on the presence of a regulatory chromosomal domain that contains binding sites for such multifunctional nuclear proteins as the Origin Recognition Complex (ORC), Abf1p, and Rap1p, which are in turn thought to be recognized by silencing-specific proteins such as Sir1p, Sir2p, Sir3p, and Sir4p (10, 11, 5). The congregation of all these factors leads to the assembly of a chromatin silencing complex, and a domain of silenced chromatin (7). Sir1p seems to be involved in the establishment rather than the maintenance of a silenced state at HML and HMR (12, 13, 14). Sir1p likely recognizes a silencer element in the DNA through its interactions with ORC, because a small region of Sir1p found to be necessary for recognizing the HMR silencer was the same region of Sir1p required for interacting with Orc1p (11). Also, a Gal4-Sir1p fusion tethered at HMR bypassed the requirement for both the silencer element and ORC in silencing that locus, but still required passage through S phase and the presence of the other Sir proteins for silencing (5, 14, 15). Sir1p is the only Sir protein that appears not to be involved in telomeric silencing (13)

Last updated: 1999-09-01

REFERENCES CITED ON THIS PAGE [View Complete Literature Guide for SIR1]

1) Rine J, et al.  (1979) A suppressor of mating-type locus mutations in Saccharomyces cerevisiae: evidence for and identification of cryptic mating-type loci. Genetics 93(4):877-901
2) Rine J and Herskowitz I  (1987) Four genes responsible for a position effect on expression from HML and HMR in Saccharomyces cerevisiae. Genetics 116(1):9-22
3) Sharp JA, et al.  (2003) The budding yeast silencing protein Sir1 is a functional component of centromeric chromatin. Genes Dev 17(19):2356-61
4) Bose ME, et al.  (2004) The origin recognition complex and Sir4 protein recruit Sir1p to yeast silent chromatin through independent interactions requiring a common Sir1p domain. Mol Cell Biol 24(2):774-86
5) Triolo T and Sternglanz R  (1996) Role of interactions between the origin recognition complex and SIR1 in transcriptional silencing. Nature 381(6579):251-3
6) Laurenson P and Rine J  (1992) Silencers, silencing, and heritable transcriptional states. Microbiol Rev 56(4):543-60
7) Loo S and Rine J  (1994) Silencers and domains of generalized repression. Science 264(5166):1768-71
8) Shore D  (1994) RAP1: a protean regulator in yeast. Trends Genet 10(11):408-12
9) Loo S and Rine J  (1995) Silencing and heritable domains of gene expression. Annu Rev Cell Dev Biol 11:519-48
10) Kimmerly W, et al.  (1988) Roles of two DNA-binding factors in replication, segregation and transcriptional repression mediated by a yeast silencer. EMBO J 7(7):2241-53
11) Gardner KA, et al.  (1999) A region of the Sir1 protein dedicated to recognition of a silencer and required for interaction with the Orc1 protein in saccharomyces cerevisiae. Genetics 151(1):31-44
12) Pillus L and Rine J  (1989) Epigenetic inheritance of transcriptional states in S. cerevisiae. Cell 59(4):637-47
13) Aparicio OM, et al.  (1991) Modifiers of position effect are shared between telomeric and silent mating-type loci in S. cerevisiae. Cell 66(6):1279-87
14) Fox CA, et al.  (1997) The origin recognition complex, SIR1, and the S phase requirement for silencing. Science 276(5318):1547-51
15) Chien CT, et al.  (1993) Targeting of SIR1 protein establishes transcriptional silencing at HM loci and telomeres in yeast. Cell 75(3):531-41