Dob1p (Mtr4p) is a putative ATP-dependent RNA helicase required for the 3' end formation of 5.8S rRNA in Saccharomyces cerevisiae.

The temperature-sensitive mutation, dob1-1, was identified in a screen for dependence on overexpression of the yeast translation initiation factor eIF4B (Tif3p). Dob1p is an essential putative ATP-dependent RNA helicase. Polysome analyses revealed an under accumulation of 60S ribosomal subunits in the dob1-1 mutant. Pulse-chase labelling of pre-rRNA showed that this ...
was due to a defect in the synthesis of the 5.8S and 25S rRNAs. Northern and primer extension analyses in the dob1-1 mutant, or in a strain genetically depleted of Dob1p, revealed a specific inhibition of the 3' processing of the 5.8S rRNA from its 7S precursor. This processing recently has been attributed to the activity of the exosome, a complex of 3'-->5' exonucleases that includes Rrp4p. In vivo depletion of Dob1p also inhibits degradation of the 5' external transcribed spacer region of the pre-rRNA. A similar phenotype was observed in rrp4 mutant strains and, moreover, the dob1-1 and rrp4-1 mutations show a strong synergistic growth inhibition. We propose that Dob1p functions as a cofactor for the exosome complex that unwinds secondary structures in the pre-rRNA that otherwise block the progression of the 3'-->5' exonucleases.
Mesh Terms:
Cloning, Molecular, DEAD-box RNA Helicases, Eukaryotic Initiation Factors, Exoribonucleases, Fungal Proteins, Galactose, Mutagenesis, Nuclear Proteins, Peptide Initiation Factors, Phenotype, RNA Helicases, RNA Nucleotidyltransferases, RNA Precursors, RNA Processing, Post-Transcriptional, RNA, Ribosomal, 5S, RNA-Binding Proteins, Ribosomal Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
EMBO J.
Date: Feb. 16, 1998
Download Curated Data For This Publication
17117
Switch View:
  • Interactions 1