The H/ACA RNP assembly factor SHQ1 functions as an RNA mimic

Genes Dev. 2011 Nov 15;25(22):2398-408. doi: 10.1101/gad.176834.111.


SHQ1 is an essential assembly factor for H/ACA ribonucleoproteins (RNPs) required for ribosome biogenesis, pre-mRNA splicing, and telomere maintenance. SHQ1 binds dyskerin/NAP57, the catalytic subunit of human H/ACA RNPs, and this interaction is modulated by mutations causing X-linked dyskeratosis congenita. We report the crystal structure of the C-terminal domain of yeast SHQ1, Shq1p, and its complex with yeast dyskerin/NAP57, Cbf5p, lacking its catalytic domain. The C-terminal domain of Shq1p interacts with the RNA-binding domain of Cbf5p and, through structural mimicry, uses the RNA-protein-binding sites to achieve a specific protein-protein interface. We propose that Shq1p operates as a Cbf5p chaperone during RNP assembly by acting as an RNA placeholder, thereby preventing Cbf5p from nonspecific RNA binding before association with an H/ACA RNA and the other core RNP proteins.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Survival
  • Humans
  • Hydro-Lyases / chemistry
  • Hydro-Lyases / metabolism
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / metabolism
  • Models, Molecular*
  • Molecular Mimicry*
  • Mutation
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Folding
  • Protein Structure, Tertiary
  • RNA, Fungal / metabolism
  • Recombinant Proteins / metabolism
  • Ribonucleoproteins, Small Nuclear / chemistry
  • Ribonucleoproteins, Small Nuclear / metabolism
  • Ribonucleoproteins, Small Nucleolar / chemistry
  • Ribonucleoproteins, Small Nucleolar / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae* / chemistry
  • Saccharomyces cerevisiae* / genetics
  • Saccharomyces cerevisiae* / metabolism


  • Microtubule-Associated Proteins
  • NAP57
  • Nuclear Proteins
  • RNA, Fungal
  • Recombinant Proteins
  • Ribonucleoproteins, Small Nuclear
  • Ribonucleoproteins, Small Nucleolar
  • Saccharomyces cerevisiae Proteins
  • Shq1 protein, S cerevisiae
  • Hydro-Lyases
  • CBF5 protein, S cerevisiae