Evidence for silencing compartments within the yeast nucleus: a role for telomere proximity and Sir protein concentration in silencer-mediated repression.
Open Access
- 15 July 1996
- journal article
- Published by Cold Spring Harbor Laboratory in Genes & Development
- Vol. 10 (14), 1796-1811
- https://doi.org/10.1101/gad.10.14.1796
Abstract
Transcriptional repression at the silent mating-type loci in yeast requires the targeting of silent information regulator (Sir) proteins through specific interactions formed at cis-acting silencer elements. We show here that a reporter gene flanked by two functional silencers is not repressed when integrated at >200 kb from a telomere. Repression is restored by creation of a new telomere 13 kb from the integrated reporter or by elevated expression of SIR1, SIR3, and/or SIR4. Coupled expression represses in an additive manner, suggesting that all three factors are in limiting concentrations. When overexpressed, Sir3 and Sir4 are dispersed throughout the nucleoplasm, in contrast to wild-type cells where they are clustered in a limited number of foci together with telomeres. Efficient silencer function thus seems to require either proximity to a pool of concentrated Sir proteins, that is, proximity to telomeres, or delocalization of the silencing factors.Keywords
This publication has 53 references indexed in Scilit:
- The carboxy termini of Sir4 and Rap1 affect Sir3 localization: evidence for a multicomponent complex required for yeast telomeric silencing.The Journal of cell biology, 1995
- Telomere maintenance and gene repression: a common end?Current Opinion in Cell Biology, 1994
- Internal tracts of telomeric DNA act as silencers in Saccharomyces cerevisiae.Genes & Development, 1994
- SIR3 and SIR4 proteins are required for the positioning and integrity of yeast telomeresCell, 1993
- Yeast origin recognition complex is involved in DNA replication and transcriptional silencingNature, 1993
- Localization of RAP1 and topoisomerase II in nuclei and meiotic chromosomes of yeastThe Journal of cell biology, 1992
- A position effect on the time of replication origin activation in yeastCell, 1992
- Modifiers of position effect are shared between telomeric and silent mating-type loci in S. cerevisiaeCell, 1991
- Generation of high specificity of effect through low-specificity binding of proteins to DNAFEBS Letters, 1988
- A yeast silencer contains sequences that can promote autonomous plasmid replication and transcriptional activationCell, 1987