Multiple Yeast Genes Affect Telomere Length via Telomerase RNA Abundance, Including the Paf1 Complex

Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA

^* To whom correspondence should be addressed. Email: amy.mozdy{at}utah.edu.

	Abstract

Two-fold reductions in telomerase RNA levels cause telomere shortening in both humans and yeast. To test whether multiple genes that affect telomere length act through telomerase RNA abundance, we used real-time RT-PCR to screen Saccharomyces cerevisiae deletion strains reported to maintain shorter or longer telomeres for their telomerase RNA (TLC1) abundance. Of 290 strains screened, five have increased TLC1 levels; four of these maintain longer telomeres. Twenty strains have decreased TLC1 levels; eighteen of these are known to maintain shorter telomeres. Four strains with decreased TLC1 RNA are deleted for subunits of Paf1C (Polymerase II-associated factor complex). While Paf1C has been implicated in the transcription of both polyadenylated and nonpolyadenylated RNAs, Paf1C has not been previously associated with the non-coding telomerase RNA. In Paf1C mutant strains, TLC1 overexpression partially rescues telomere length and cell growth defects, suggesting that telomerase RNA is a critical direct or indirect Paf1C target. Other factors newly identified as affecting TLC1 RNA levels include cyclin-dependent kinase, the mediator complex, protein phosphatase 2A, and ribosomal proteins L13B and S16A. This study establishes the generality of telomere length genes acting at the level of telomerase RNA abundance.