title: An enhanced H/ACA RNP assembly mechanism for human telomerase RNA.
abstract: The integral telomerase RNA subunit templates the synthesis of telomeric repeats. The biological accumulation of human telomerase RNA (hTR) requires hTR H/ACA domain assembly with the same proteins that assemble on other human H/ACA RNAs. Despite this shared RNP composition, hTR accumulation is particularly sensitized to disruption by disease-linked H/ACA protein variants. We show that contrary to expectation, hTR-specific sequence requirements for biological accumulation do not act at an hTR-specific step of H/ACA RNP biogenesis; instead, they enhance hTR binding to the shared, chaperone-bound scaffold of H/ACA core proteins that mediates initial RNP assembly. We recapitulate physiological H/ACA RNP assembly with a preassembled NAF1/dyskerin/NOP10/NHP2 scaffold purified from cell extract and demonstrate that distributed sequence features of the hTR 3' hairpin synergize to improve scaffold binding. Our findings reveal that the hTR H/ACA domain is distinguished from other human H/ACA RNAs not by a distinct set of RNA-protein interactions but by an increased efficiency of RNP assembly. Our findings suggest a unifying mechanism for human telomerase deficiencies associated with H/ACA protein variants.
authors.affiliation: Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, USA.
authors.forename: Emily D
authors.initials: ED
authors.lastname: Egan
authors.forename: Kathleen
authors.initials: K
authors.lastname: Collins
mesh_terms: D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D009690:Nucleic Acid Conformation; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D012313:RNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012320:RNA Polymerase III / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry / Q000378:metabolism; D020718:Ribonucleoproteins, Small Nucleolar / Q000737:chemistry / Q000378:metabolism; D019098:Telomerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C112148:DKC1 protein, human; D046911:Macromolecular Substances; C551999:NAF1 protein, human; C416929:NHP2 protein, human; C416930:NOP10 protein, human; D009687:Nuclear Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D020718:Ribonucleoproteins, Small Nucleolar; C422952:telomerase RNA; D012313:RNA; D012319:RNA Polymerase II; D019098:Telomerase; D012320:RNA Polymerase III