Abstract
Box H/ACA small nucleolar ribonucleoprotein particles (snoRNPs) contain four essential proteins, Cbf5p, Gar1p, Nhp2p, and Nop10p, each of which, with the exception of Gar1p, is required for box H/ACA snoRNA accumulation. Database searches identified a novel essential protein, which we termed Naf1p, with a region of homology to the RNA-binding domain of Gar1p and other features in common with hnRNP-like proteins. Naf1p is localized to the nucleus and is not a stable component of the H/ACA snoRNPs, but it is required for the accumulation of all box H/ACA snoRNAs. This requirement is not at the level of snoRNA transcription initiation or termination. Naf1 p shows in vitro RNA-binding activity and also binds directly to Cbf5p and Nhp2p. Naf1p was shown to bind to the CTD in vivo in a two-hybrid assay, and the phosphorylated CTD, but not the nonphosphorylated CTD, was shown to precipitate tagged Naf1p from a cell lysate. We propose that Naf1 p is recruited to the CTD of RNA polymerase II and binds to nascent box H/ACA snoRNAs promoting snoRNP assembly.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Amino Acid Motifs
-
Amino Acid Sequence
-
Binding Sites
-
Cell Nucleus / metabolism
-
Fungal Proteins / genetics
-
Fungal Proteins / metabolism*
-
Hydro-Lyases / genetics
-
Hydro-Lyases / metabolism
-
Microtubule-Associated Proteins / genetics
-
Microtubule-Associated Proteins / metabolism
-
Molecular Sequence Data
-
Nuclear Proteins / genetics
-
Nuclear Proteins / metabolism*
-
RNA Polymerase II / genetics
-
RNA Polymerase II / metabolism*
-
RNA Processing, Post-Transcriptional
-
RNA, Ribosomal / metabolism
-
RNA, Small Nucleolar / biosynthesis
-
RNA-Binding Proteins / genetics
-
RNA-Binding Proteins / metabolism
-
Recombinant Proteins / genetics
-
Recombinant Proteins / metabolism
-
Ribonucleoproteins, Small Nuclear / genetics
-
Ribonucleoproteins, Small Nuclear / metabolism
-
Ribonucleoproteins, Small Nucleolar / genetics
-
Ribonucleoproteins, Small Nucleolar / metabolism*
-
Saccharomyces cerevisiae Proteins / genetics
-
Saccharomyces cerevisiae Proteins / metabolism
-
Sequence Homology, Amino Acid
-
Transcription, Genetic
-
Yeasts / genetics
-
Yeasts / metabolism
Substances
-
Fungal Proteins
-
Microtubule-Associated Proteins
-
Nuclear Proteins
-
RNA, Ribosomal
-
RNA, Small Nucleolar
-
RNA-Binding Proteins
-
Recombinant Proteins
-
Ribonucleoproteins, Small Nuclear
-
Ribonucleoproteins, Small Nucleolar
-
Saccharomyces cerevisiae Proteins
-
NHP2 protein, S cerevisiae
-
GAR1 protein, S cerevisiae
-
RNA Polymerase II
-
Hydro-Lyases
-
CBF5 protein, S cerevisiae