The box H/ACA RNP assembly factor Naf1p contains a domain homologous to Gar1p mediating its interaction with Cbf5p

J Mol Biol. 2007 Aug 31;371(5):1338-53. doi: 10.1016/j.jmb.2007.06.031. Epub 2007 Jun 16.


Naf1 is an essential protein involved in the maturation of box H/ACA ribonucleoproteins, a group of particles required for ribosome biogenesis, modification of spliceosomal small nuclear RNAs and telomere synthesis. Naf1 participates in the assembly of the RNP at transcription sites and in the nuclear trafficking of the complex. The crystal structure of a domain of yeast Naf1p, Naf1Delta1p, reveals a striking structural homology with the core domain of archaeal Gar1, an essential protein component of the mature RNP; it suggests that Naf1p and Gar1p have a common binding site on the enzymatic protein component of the particle, Cbf5p. We propose that Naf1p is a competitive binder for Cbf5p, which is replaced by Gar1p during maturation of the H/ACA particle. The exchange of Naf1p by Gar1p might be prompted by external factors that alter the oligomerisation state of Naf1p and Gar1p. The structural homology with Gar1 suggests that the function of Naf1 involves preventing non-cognate RNAs from being loaded during transport of the particle by inducing a non-productive conformation of Cbf5.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Dimerization
  • Fungal Proteins / chemistry*
  • Fungal Proteins / physiology
  • Hydro-Lyases / chemistry*
  • Hydro-Lyases / physiology
  • Microtubule-Associated Proteins / chemistry*
  • Microtubule-Associated Proteins / physiology
  • Models, Molecular
  • Molecular Conformation
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / physiology
  • Protein Structure, Tertiary
  • RNA / chemistry
  • RNA, Small Nuclear / chemistry
  • Ribonucleoproteins, Small Nuclear / chemistry*
  • Ribonucleoproteins, Small Nuclear / physiology
  • Ribonucleoproteins, Small Nucleolar / chemistry*
  • Ribonucleoproteins, Small Nucleolar / physiology
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / physiology
  • Sequence Homology, Amino Acid
  • Surface Properties


  • Fungal Proteins
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • RNA, Small Nuclear
  • Ribonucleoproteins, Small Nuclear
  • Ribonucleoproteins, Small Nucleolar
  • Saccharomyces cerevisiae Proteins
  • GAR1 protein, S cerevisiae
  • RNA
  • Hydro-Lyases
  • CBF5 protein, S cerevisiae