Intellectual Merit. Maintaining the genome in the form of linear chromosomes poses significant challenges for eukaryotic cells. In particular, how to fully duplicate the chromosome termini (telomeres) and how to prevent sequence loss or inappropriate rearrangements at telomeres are critical issues. Key factors involved in solving these problems include the telomerase enzyme, which adds short G-rich repeats to one DNA strand of the telomere, and capping proteins that bind to telomeric sequences. Telomerase compensates for loss of telomeric sequences during replication, while capping proteins afford protection from enzymes that would otherwise degrade, unwind, or inappropriately recombine the ends. Interestingly, the DNA replication machinery, and the polymerase alpha-primase complex (Pol alpha) in particular, has been shown to have functional and physical connections with both telomerase and telomere capping activities. Based on this, the goal of this project is to understand at a molecular level how the function of telomere capping proteins and telomerase are coordinated with the DNA replication machinery. The budding yeast, Saccharomyces cerevisiae, will be used to investigate three issues that are relevant to this goal. First, do the telomere capping proteins Cdc13, Stn1 and Ten1 recruit Pol alpha; to newly extended telomeres? Second, do Cdc13, Stn1 and Ten1 enhance terminal replication fork progression or stability? Third, does Pol alpha; negatively regulate the processivity of telomerase? Answers to these questions have the potential to significantly expand our understanding of the mechanisms that coordinate telomere replication and telomere capping, and will undoubtedly provide insights that can be further tested in other organisms.
Broader Impacts. Undergraduate and graduate students will carry out this project and participate in weekly presentations and discussions of experiments and related literature. The findings will be shared through participation of the students in local, national, and international conferences as well as publication in peer-reviewed journals. Since a relatively large proportion of the student population at UCR comprises underrepresented groups in science, increasing the opportunities for hands-on research will help to broaden the participation of these groups in science, exposing them to the excitement of discovery.
