Analysis of Sir2p Domains Required for rDNA and Telomeric Silencing in <i>Saccharomyces cerevisiae</i>

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Analysis of Sir2p Domains Required for rDNA and Telomeric Silencing in Saccharomyces cerevisiae

COCKELL, Moira M., PERROD, Severine, GASSER, Susan Margaret


Silent information regulator (Sir) 2 is a limiting component of the Sir2/3/4 complex, which represses transcription at subtelomeric and HM loci. Sir2p also acts independently of Sir3p and Sir4p to influence chromatin organization in the rDNA locus. Deleted and mutated forms of Sir2p have been tested for their ability to complement and/or to disrupt silencing. The highly conserved C-terminal domain of Sir2p (aa 199-562) is insufficient to restore repression at either telomeric or rDNA reporters in a sir2Delta background and fails to nucleate silencing when targeted to an appropriate reporter gene. However, its expression in an otherwise wild-type strain disrupts telomeric repression. Similarly, a point mutation (P394L) within this conserved core inactivates the full-length protein but renders it dominant negative for all types of silencing. Deletion of aa 1-198 from Sir2(394L) eliminates its dominant negative effect.

Thus we define two distinct functional domains in Sir2p, both essential for telomeric and rDNA repression: the conserved core domain found within aa 199-562 and a second domain that encompasses aa 94-198. [...]

COCKELL, Moira M., PERROD, Severine, GASSER, Susan Margaret. Analysis of Sir2p Domains Required for rDNA and Telomeric Silencing in Saccharomyces cerevisiae . Genetics , 2000, vol. 154, no. 3, p. 1069-1083

PMID : 10757754

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Copyright2000 by the Genetics Society of America


In the article byMoira M. Cockell, Severine Perrod andSusan M. Gasser(Genetics154:1069–1083) entitled

“Analysis of Sir2p Domains RequiredforrDNA and Telomeric SilencinginSaccharomycescerevisiae,”the plasmids usedinthis study carrying the full-length or coreSIR2gene labeled as sir2-394Lhave point mutations that resultin the substitution of amino acid residues Arg403 and Arg404 by glycines, in addition to the reported replacement of the conserved pro- line residue at amino acid 394 by leucine. The Pro394 to Leu mutation alone eliminates Sir2p function and confers a dominant negative phenotypefortelomeric silencing similar tothatreported. A detailed analysis of differences contributed bythesetwo additional mutations will be presented elsewhere.

In the article byLuiz O. F. Penalva, M. Fernanda Ruiz, Angeles Ortega, Begon˜a Granadino, Luis Vicente, Car- men Segarra,Jua´n Valca´rcelandLucas Sa´nchez(Genet- ics155:129–139) entitled “The Drosophilafl(2)dGene, Re- quiredfor Female-Specific Splicing ofSxlandtraPre-mRNAs, Encodes a Novel Nuclear Protein With a HQ-Rich Domain,”

on page 129inthe second paragraphinlines 8to 12thetext should be:“virilizer(vir)(Hilfikeret al.1995), which encodes a protein of 1854 amino acids withoutsignificant homologies to proteins in databases (M. Niessen andR. No¨thiger,per- sonal communication).”

Genetics155:2021 (August 2000)



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