title: Structural study of elements of Tetrahymena telomerase RNA stem-loop IV domain important for function.
abstract: Tetrahymena telomerase RNA (TER) contains several regions in addition to the template that are important for function. Central among these is the stem-loop IV domain, which is involved in both catalysis and RNP assembly, and includes binding sites for both the holoenzyme assembly protein p65 and telomerase reverse transcriptase (TERT). Stem-loop IV contains two regions with high evolutionary sequence conservation: a central GA bulge between helices, and a terminal loop. We solved the solution structure of loop IV and modeled the structure of the helical region containing the GA bulge, using NMR and residual dipolar couplings. The central GA bulge with flanking C-G base pairs induces a approximately 50 degrees semi-rigid bend in the helix. Loop IV is highly structured, and contains a conserved C-U base pair at the top of the helical stem. Analysis of new and previous biochemical data in light of the structure provides a rationale for some of the sequence conservation in this region of TER. The results suggest that during holoenzyme assembly the protein p65 recognizes a bend in stem IV, and this binding to central stem IV helps to position the structured loop IV for interaction with TERT and other region(s) of TER.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of South Bohemia, Czech Republic.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Richards
authors.forename: Haihong
authors.initials: H
authors.lastname: Wu
authors.forename: Lukas
authors.initials: L
authors.lastname: Trantirek
authors.forename: Catherine M
authors.initials: CM
authors.lastname: O'Connor
authors.forename: Kathleen
authors.initials: K
authors.lastname: Collins
authors.forename: Juli
authors.initials: J
authors.lastname: Feigon
mesh_terms: D000818:Animals; D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D020035:Holoenzymes / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D016053:RNA, Protozoan / Q000378:metabolism*; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D013698:Templates, Genetic; D016808:Tetrahymena thermophila / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D020035:Holoenzymes; D015800:Protozoan Proteins; D016053:RNA, Protozoan; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase