Many RNA nucleases and helicases participate in ribosome biogenesis, but how they cooperate with each other is largely unknown. Here we report that in vivo cleavage of the yeast pre-rRNA at site D, the 3' end of the 18S rRNA, requires functional interactions between PIN domain protein Nob1 and the DEAH box RNA helicase Prp43. Nob1 showed specific cleavage on a D-site substrate analogue in vitro, which was abolished by mutations in the Nob1 PIN domain or the RNA substrate. Genetic analyses linked Nob1 to the late pre-40S associated factor Ltv1, the RNA helicase Prp43 and its cofactor Pfa1. In strains lacking Ltv1, mutation of Prp43 or Pfa1 led to a striking accumulation of 20S pre-rRNA in the cytoplasm due to inhibition of site D cleavage. This phenotype was suppressed by increased dosage of wild-type Nob1, but not by Nob1 variants mutated in the catalytic site. In ltv1/pfa1 mutants the 20S pre-rRNA was susceptible to 3' to 5' degradation by the cytoplasmic exosome. This degraded into the 3' region of the 18S rRNA, strongly indicating that the pre-ribosomes are structurally defective.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|