Mutational analysis of the Tetrahymena telomerase RNA: identification of residues affecting telomerase activity in vitro
Greider, Carol W.
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Telomere-specific repeat sequences are essential for chromosome end stability. Telomerase maintains telomere length by adding sequences de novo onto chromosome ends. The template domain of the telomerase RNA component dictates synthesis of species-specific telomeric repeats and other regions of the RNA have been suggested to be important for enzyme structure and/or catalysis. Using enzyme reconstituted in vitro with RNAs containing deletions or substitutions we identified nucleotides in the RNA component that are important for telomerase activity. Although many changes to conserved features in the RNA secondary structure did not abolish enzyme activity, levels of activity were often greatly reduced, suggesting that regions other than the template play a role in telomerase function. The template boundary was only altered by changes in stem II that affected the conserved region upstream of the template, not by changes in other regions, such as stems I, III and IV, consistent with a role of the conserved region in defining the 5' boundary of the template. Surprisingly, telomerase RNAs with substitutions or deletion of residues potentially abolishing the conserved pseudoknot structure had wild-type levels of telomerase activity. This suggests that this base pairing interaction may not be required for telomerase activity per se but may be conserved as a regulatory site for the enzyme in vivo.
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Shay, Jerry W.; Avilion, Ariel A.; Piatyszek, Mieczyslaw A.; Gupta, Jyothi; Greider, Carol W.; Bacchetti, Silvia (American Association of Cancer Research, 1996-02-01)Telomerase activity has been detected in many human immortal cells lines and in tumor tissues, whereas it is generally absent from primary cell strains and from many tumor adjacent tissue samples. With the recently cloned ...
Herr, Winship; Greider, Carol W.; Villeponteau, Bryant; Feng, Junli; Funk, Walter D.; Blasco, Maria A.; Hinckley, Craig S. (Oxford University Press, 1998-01-15)Telomerase is a ribonucleoprotein enzyme with an essential RNA component. Embedded within the telomerase RNA is a template sequence for telomere synthesis. We have characterized the structure of the 5' regions of the human ...
Lebo, Kevin J (2014-06-30)In eukaryotic cells, the ends of the chromosomes are capped by structures known as telomeres, comprised of repeated DNA segments bound by proteins. Many organisms employ a ribonucleoprotein (RNP) complex, telomerase, to ...