Protosilencers in Saccharomyces cerevisiae subtelomeric regions.
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.
Lebrun
E
E
Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665 CNRS/ENSL, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Revardel
E
E
Boscheron
C
C
Li
R
R
Gilson
E
E
Fourel
G
G
D001483:Base Sequence; D017931:DNA Primers; D005656:Fungal Proteins / Q000235:genetics; D020868:Gene Silencing; D005800:Genes, Fungal; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D016615:Telomere; D015534:Trans-Activators / Q000235:genetics
D017931:DNA Primers; D005656:Fungal Proteins; C084122:SIR3 protein, S cerevisiae; C061573:SIR4 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D015534:Trans-Activators