title: Pyrimidine motif triple helix in the Kluyveromyces lactis telomerase RNA pseudoknot is essential for function in vivo.
abstract: Telomerase is a ribonucleoprotein complex that extends the 3' ends of linear chromosomes. The specialized telomerase reverse transcriptase requires a multidomain RNA (telomerase RNA, TER), which includes an integral RNA template and functionally important template-adjacent pseudoknot. The structure of the human TER pseudoknot revealed that the loops interact with the stems to form a triple helix shown to be important for activity in vitro. A similar triple helix has been predicted to form in diverse fungi TER pseudoknots. The solution NMR structure of the Kluyveromyces lactis pseudoknot, presented here, reveals that it contains a long pyrimidine motif triple helix with unexpected features that include three individual bulge nucleotides and a C(+)•G-C triple adjacent to a stem 2-loop 2 junction. Despite significant differences in sequence and base triples, the 3D shape of the human and K. lactis TER pseudoknots are remarkably similar. Analysis of the effects of nucleotide substitutions on cell growth and telomere lengths provides evidence that this conserved structure forms in endogenously assembled telomerase and is essential for telomerase function in vivo.
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095-1569, USA.
authors.forename: Darian D
authors.initials: DD
authors.lastname: Cash
authors.forename: Osnat
authors.initials: O
authors.lastname: Cohen-Zontag
authors.forename: Nak-Kyoon
authors.initials: NK
authors.lastname: Kim
authors.forename: Kinneret
authors.initials: K
authors.lastname: Shefer
authors.forename: Yogev
authors.initials: Y
authors.lastname: Brown
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Ulyanov
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Tzfati
authors.forename: Juli
authors.initials: J
authors.lastname: Feigon
mesh_terms: D001483:Base Sequence; D006801:Humans; D007716:Kluyveromyces / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D016296:Mutagenesis; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D011743:Pyrimidines / Q000737:chemistry; D012313:RNA / Q000737:chemistry* / Q000235:genetics; D020871:RNA Stability; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D019098:Telomerase / Q000737:chemistry* / Q000235:genetics
chemical_list: D011743:Pyrimidines; D012329:RNA, Bacterial; D012331:RNA, Fungal; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; C030986:pyrimidine
keywords: Hoogsteen; RNA structure; RNA triplex; yeast