title: Structure and sequence elements of the CR4/5 domain of medaka telomerase RNA important for telomerase function.
abstract: Telomerase is a unique reverse transcriptase that maintains the 3' ends of eukaryotic chromosomes by adding tandem telomeric repeats. The RNA subunit (TR) of vertebrate telomerase provides a template for reverse transcription, contained within the conserved template/pseudoknot domain, and a conserved regions 4 and 5 (CR4/5) domain, all essential for catalytic activity. We report the nuclear magnetic resonance (NMR) solution structure of the full-length CR4/5 domain from the teleost fish medaka (Oryzias latipes). Three helices emanate from a structured internal loop, forming a Y-shaped structure, where helix P6 stacks on P5 and helix P6.1 points away from P6. The relative orientations of the three helices are Mg2+ dependent and dynamic. Although the three-way junction is structured and has unexpected base pairs, telomerase activity assays with nucleotide substitutions and deletions in CR4/5 indicate that none of these are essential for activity. The results suggest that the junction is likely to change conformation in complex with telomerase reverse transcriptase and that it provides a flexible scaffold that allows P6 and P6.1 to correctly fold and interact with telomerase reverse transcriptase.
authors: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA, Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 136-791, Republic of Korea and Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors: Nak-Kyoon
authors: NK
authors: Kim
authors: Qi
authors: Q
authors: Zhang
authors: Juli
authors: J
authors: Feigon
mesh_terms: D000818:Animals; D008274:Magnesium / Q000737:chemistry; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D009990:Oryzias / Q000235:genetics*; D012313:RNA / Q000737:chemistry*; D019098:Telomerase / Q000737:chemistry / Q000378:metabolism*
chemical_list: C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; D008274:Magnesium