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. 2001 May;158(1):167–176. doi: 10.1093/genetics/158.1.167

Protosilencers in Saccharomyces cerevisiae subtelomeric regions.

E Lebrun 1, E Revardel 1, C Boscheron 1, R Li 1, E Gilson 1, G Fourel 1
PMCID: PMC1461618  PMID: 11333227

Abstract

Saccharomyces cerevisiae subtelomeric repeats contain silencing elements such as the core X sequence, which is present at all chromosome ends. When transplaced at HML, core X can enhance the action of a distant silencer without acting as a silencer on its own, thus fulfilling the functional definition of a protosilencer. Here we show that an ACS motif and an Abf1p-binding site participate in the silencing capacity of core X and that their effects are additive. In addition, in a variety of settings, core X was found to bring about substantial gene repression only when a low level of silencing was already detectable in its absence. Adjoining an X-STAR sequence, which naturally abuts core X in subtelomeric regions, did not improve the silencing capacity of core X. We propose that protosilencers play a major role in a variety of silencing phenomena, as is the case for core X, which acts as a silencing relay, prolonging silencing propagation away from telomeres.

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Selected References

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