9318918 Lustig The long-term goal of this research is to understand the protein-DNA interactions that confer the unique structural, replication and functional properties of telomeres. RAP1 is the first eukaryotic telomere binding protein amenable to both genetic and molecular analysis. A wide array of telomere-related phenotypes have been observed in rap1 mutant strains of the yeast Saccharomyces cerevisiae, including loss of telomere size control and stability, as well as the altered expression of telomere- adjacent genes. The genetic and molecular analysis of these rap1 mutant strains addresses three critical questions. First, what is the nature of binding protein interactions that influence telomere position effects, size control and stability? Second, what is the role of telomere structure in regulating long range position effects and telomere size control? Finally, what other factors associate with the telomere to maintain its structure and function? This project addresses these questions with three specific interrelated aims. The first aim is to evaluate the role of RAP1 in maintaining the fidelity of telomere addition or repair. The second aim is to investigate the domains of RAP1 important in telomere function. The third aim is to identify and characterize extragenic suppressors of rap1 nonsense and missense alleles. %%% Telomeres, the unique protein-DNA structures present at the termini of linear eukaryotic chromosomes, are essential for maintaining chromosome stability and structure. First, telomeres serves as "caps" to protect chromosomes against degradation and rearrangement. Second, telomeric DNA serves as substrate for a unique non-DNA templated mechanism of replication that prevents the loss of terminal (and ultimately essential) sequences. Third, telomeres have long range effects on the transcription, replication, and chromatin structures of adjacent genes and sequences. The functional importance of telomeres is underscored by ev idence linking loss of telomeric sequences to cellular senescence, tumor formation , and oncogenesis. Hence, an understanding of the proteins that interact with telomeric DNA is of general importance. This project is a genetic and molecular analysis of such a protein, designated RAP1, from the yeast Saccharomyces cerevisiae. ***
