ИСТИНА

Telomerase is a key participant of telomere length maintaining system in the majority of eukaryotes. It synthesizes telomere repeats at the 3′-end of telomeric DNA using its own RNA template. The Saccharomyces cerevisiae telomerase contains besides the reverse transcriptase subunit and RNA subunit Est1, which is necessary for telomerase attachment to telomeres and telomerase activation, and Est3 with an unknown function. It is also believed that Est1 is able to catalyze G-quadruplex formation from telomeric repeats. In the same time Est3 is predicted to have an OB-fold. Its ability to interact with single strand telomeric DNA has long been discussed in the literature. We have tested the ability of Est3 from two organisms (S. cerevisiae and H. polymorpha) to interact with telomeric quadruplexes and shown serious differences in the properties of these proteins.