Structure of stem-loop IV of Tetrahymena telomerase RNA

• Published in: The EMBO journal Vol. 25; no. 13; pp. 3156 - 3166
• Main Authors: Chen, Yu, Fender, Jessica, Legassie, Jason D, Jarstfer, Michael B, Bryan, Tracy M, Varani, Gabriele
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 12.07.2006; Blackwell Publishing Ltd
• Subjects: Animals; Base Sequence; Binding sites; DNA-Binding Proteins - chemistry; Enzyme Activation; Enzymes; Models, Molecular; Molecular Sequence Data; Molecular structure; Mutation; NMR; Nucleic Acid Conformation; Proteins; Ribonucleic acid; ribonucleoprotein; RNA; RNA - chemistry; RNA - genetics; RNA structure; RNA, Protozoan - chemistry; stem-loop; telomerase; Telomerase - chemistry; Telomerase - genetics; Tetrahymena thermophila; Tetrahymena thermophila - enzymology
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7601195

Conserved domains within the RNA component of telomerase provide the template for reverse transcription, recruit protein components to the holoenzyme and are required for enzymatic activity. Among the functionally essential domains in ciliate telomerase RNA is stem‐loop IV, which strongly stimulates telomerase activity and processivity even when provided in trans. The NMR structure of Tetrahymena thermophila stem‐loop IV shows a highly structured distal stem‐loop linked to a conformationally flexible template‐proximal region by a bulge that severely kinks the entire RNA. Through extensive structure–function studies, we identify residues that contribute to both these structural features and to enzymatic activity, with no apparent effect on the binding of TERT protein. We propose that the bending induced by the GA bulge and the flexibility of the template‐proximal region allow positioning of the prestructured apical loop during the catalytic cycle.