Abstract:

Telomeres are nucleo-protein structures that cap the ends of linear chromosomes. These caps protect chromosome ends from degradation and end-to-end fusions. Telomeres also solve the end replication problem, which is the gradual loss of genetic sequence from chromosome ends over successive rounds of DNA replication. Telomeres consist of simple sequence repeats. As they do not contain critical genetic information, telomeres can shorten in length without a concomitant loss in the cell's genetic information. However, sequence loss cannot go unchecked as telomeres are of a finite length and sequence degradation can damage open reading frames internal to the telomeres.

Telomerase, a specialized reverse transcriptase, lengthens telomeres in Saccharomyces cerevisiae cells. This organism is more commonly known as Baker's yeast, and is a good model organism for the study of telomerase and telomase-associated proteins. Telomerase activity in yeast requires several key genes: TLC1, EST2, EST1, EST2 , and CDC13 .

In this thesis, chromatin immunoprecipitation (ChIP) experiments were used to determine the levels of binding of Myc epitope-tagged Est1p, Est2p, and Cdc13p with the yeast telomere over the course of the cell cycle in mec1Δ, tel1Δ, and mre11Δ single mutant strains, as well as wild-type. These three mutant strains have defects in telomere-length maintenance, and appear to be required for the telomerase pathway of telomere length maintenance. ChIP analysis showed that these mutant strains did show characteristic alterations in cell-cycle regulated association of these telomerase-associated proteins when compared to isogenic wild-type association profiles.