An enhanced H/ACA RNP assembly mechanism for human telomerase RNA

Mol Cell Biol. 2012 Jul;32(13):2428-39. doi: 10.1128/MCB.00286-12. Epub 2012 Apr 23.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Base Sequence
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Macromolecular Substances / chemistry
  • Macromolecular Substances / metabolism
  • Models, Molecular
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism
  • Nucleic Acid Conformation
  • Protein Interaction Domains and Motifs
  • Protein Multimerization
  • RNA / chemistry*
  • RNA / genetics
  • RNA / metabolism
  • RNA Polymerase II / genetics
  • RNA Polymerase II / metabolism
  • RNA Polymerase III / genetics
  • RNA Polymerase III / metabolism
  • Ribonucleoproteins / chemistry*
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism
  • Ribonucleoproteins, Small Nuclear / chemistry
  • Ribonucleoproteins, Small Nuclear / metabolism
  • Ribonucleoproteins, Small Nucleolar / chemistry
  • Ribonucleoproteins, Small Nucleolar / metabolism
  • Telomerase / chemistry*
  • Telomerase / genetics
  • Telomerase / metabolism

Substances

  • Cell Cycle Proteins
  • DKC1 protein, human
  • Macromolecular Substances
  • NAF1 protein, human
  • NHP2 protein, human
  • NOP10 protein, human
  • Nuclear Proteins
  • Ribonucleoproteins
  • Ribonucleoproteins, Small Nuclear
  • Ribonucleoproteins, Small Nucleolar
  • telomerase RNA
  • RNA
  • RNA Polymerase II
  • Telomerase
  • RNA Polymerase III