Telomerase is a special reverse transcriptase that extends one strand of the telomere repeat by using a template embedded in an RNA subunit. Like other polymerases, telomerase is believed to use a pair of divalent metal ions (coordinated by a triad of aspartic acid residues) for catalyzing nucleotide addition. Here we show that, in the presence of manganese, both yeast and human telomerase can switch to a template- and RNA-independent mode of DNA synthesis, acting in effect as a terminal transferase. Even as a terminal transferase, yeast telomerase retains a species-dependent preference for GT-rich, telomere-like DNA on the 5′ end of the substrate. The terminal transferase activity of telomerase may account for some of the hitherto unexplained effects of telomerase overexpression on cell physiology. © 2005 by The National Academy of Sciences of the USA.
Lue, N. F., Bosoy, D., Moriarty, T. J., Autexier, C., Altman, B., & Leng, S. (2005). Telomerase can act as a template- and RNA-independent terminal transferase. Proceedings of the National Academy of Sciences of the United States of America, 102(28), 9778–9783. https://doi.org/10.1073/pnas.0502252102