Telomerase function and binding at endogenous G-rich regions (ChIP)

Telomerase majorly functions at telomeres but under adverse conditions acts at endogenous regions, which is often observed in cancer calls. By mapping the global occupancy of the catalytic subunit of telomerase (Est2), we reveal that telomerase binds to multiple genomic loci, which we termed ‘non-telomere-binding sites’ (NTBS). We characterized under when and why Est2 binds to such sites and could show that telomerase is inactive but becomes activated upon global DNA damage. Indicating that those regions are of particular risk for genome stability. Using biochemical and molecular experiments we further characterized Est2 binding to NTBS. In contrast to Est2 binding to telomere neither Cdc13 nor Ku70/80 is crucial for the binding to NTBS. Strikingly, using Hi-C, we demonstrate that chromatin organization is essential and drives the interaction of Est2-NTBS binding. The here presented results provide a novel model of telomerase regulation using endogenous regions as “parking spots” awaiting its canonical function at telomeres. Wild type Saccharomyces cerevisiae cells were subjected to Hi-C to examine the interaction between teloemric and non-telomeric binding sites of catalytic subunit of telomerase.