TRANSCRIPTION OF A YEAST TELOMERE ALLEVIATES TELOMERE POSITION EFFECTWITHOUT AFFECTING CHROMOSOME STABILITY

Telomeres are required for the stable maintenance of chromosomes in th e yeast Saccharomyces cerevisiae. Telomeres also repress the expressio n of genes in their vicinity, a phenomenon known as telomere position effect. In an attempt to construct a conditional telomere, an inducibl e promoter was introduced adjacent to a single telomere of a chromosom e such that transcription could be induced toward the end of the chrom osome. Transcription toward two other essential chromosomal elements, centromeres and origins of replication, eliminates their function. In contrast, transcription toward a telomere did not affect the stability function of the telomere as measured by the loss rate of the transcri bed chromosome. Transcription proceeded through the entire length of t he telomeric tract and caused a modest reduction in the average length of the transcribed telomere. Transcription of the telomere substantia lly reduced the frequency of cells in which an adjacent URA3 gene was subject to telomere position effect. These results indicate that telom ere position effect can be alleviated without compromising chromosome stability.