Rap1p telomere association is not required for mitotic stability of a C(3)TA(2) telomere in yeast.
Telomeric DNA usually consists of a repetitive sequence: C(1-3)A/TG(1-3) in yeast, and C(3)TA(2)/T(2)AG(3) in vertebrates. In yeast, the sequence-specific DNA- binding protein Rap1p is thought to be essential for telomere function. In a tlc1h mutant, the templating region of the telomerase RNA gene is altered so that telomerase adds the vertebrate telomere sequence instead of the yeast sequence to the chromosome end. A tlc1h strain has short but stable telomeres and no growth defect. We show here that Rap1p and the Rap1p-associated Rif2p did not bind to a telomere that contains purely vertebrate repeats, while the TG(1-3) single-stranded DNA binding protein Cdc13p and the normally non-telomeric protein Tbf1p did bind this telomere. A chromosome with one entirely vertebrate-sequence telomere had a wild-type loss rate, and the telomere was maintained at a short but stable length. However, this telomere was unable to silence a telomere-adjacent URA3 gene, and the strain carrying this telomere had a severe defect in meiosis. We conclude that Rap1p localization to a C(3)TA(2) telomere is not required for its essential mitotic functions.
Alexander
Mary Kate
MK
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Zakian
Virginia A
VA
D001483:Base Sequence; D002872:Chromosome Deletion; D015825:Chromosomes, Fungal; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005800:Genes, Fungal; D008938:Mitosis; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D016615:Telomere; D034501:Telomere-Binding Proteins / Q000378:metabolism; D014157:Transcription Factors; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
C452219:Cdc13 protein, S cerevisiae; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C079376:TBF1 protein, S cerevisiae; D034501:Telomere-Binding Proteins; D014157:Transcription Factors; D020827:rap1 GTP-Binding Proteins