Structure/function analysis of the human telomerase ribonucleoprotein

• Main Author: Mitchell, James Robert
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2000
• Subjects: Microbiology
• ISBN: 0599860138; 9780599860131

Telomerase is a cellular reverse transcriptase that regulates telomere length by adding simple sequence DNA repeats to the ends of chromosomes. All telomerase ribonucleoproteins (RNPs) are composed of at least two essential components: a catalytic telomerase reverse transcriptase (TERT) and a telomerase RNA containing the template for telomere repeat addition. In this thesis I have further characterized the RNA component of the human telomerase RNP. A structural motif shared with the H/ACA small nucleolar RNAs was identified in the 3′ end of the human telomerase RNA (hTR). The conserved elements of this motif are required in vivo but not in vitro for the processing and accumulation of the mature telomerase RNA. The presence of this domain suggests a role for the nucleolus in the biogenesis of the telomerase RNP. A novel telomerase protein component associated with this conserved H/ACA motif was also identified. Previously characterized alterations in this protein cause a rare X-linked disorder known as dyskeratosis congenita (DKC). This is the first human disease associated with a defect in telomerase activity and telomere maintenance, and the phenotypes of DKC shed light on the essential role of telomerase throughout human growth and development. Finally, the interaction between the telomerase RNA and the catalytic subunit TERT was examined. Two separable regions of the telomerase RNA interact with TERT independently and largely noncooperatively. These fragments are both required for telomerase activity in vitro and in vivo. These results lay the basis for an understanding of the critical RNA-protein interactions required for human telomerase catalytic activity and may some day be useful in developing a specific inhibitor of telomerase activity for use as a general anti-cancer agent.