Arabidopsis POT1A interacts with TERT-V(18), an N-terminal splicing variant of telomerase

Chromosome integrity is maintained via the actions of ribonucleoprotein complexes that can add telomeric repeats or can protect the chromosome end from being degraded. POT1 ( protection of telomeres 1), a class of single- stranded- DNA- binding proteins, is a regulator of telomeric length. The Arabidopsis genome contains three POT1 homologues: POT1A, POT1B and POT1C. Using yeast two- hybrid assays to identify components of a potential POT1A complex, we retrieved three interactors: the N- terminus of the telomerase, a protein kinase and a plant- specific protein. Further analysis of the interaction of POT1 proteins with telomerase showed that this interaction is specific to POT1A, suggesting a specific role for this paralogue. The interaction is specific to the N- terminal region of the telomerase, which can be encoded by splicing variants. This interaction indicates possible mechanisms for telomerase regulation by alternative splicing and by POT1 proteins.