18S rRNA processing requires the RNA helicase-like protein Rrp3.
We report the identification of a new gene, RRP3 (rRNA processing), which is required for pre-rRNA processing. Rrp3 is a 60.9 kDa protein that is required for maturation of the 35S primary transcript of pre-rRNA and is required for cleavages leading to mature 18S RNA. RRP3 was identified in a PCR screen for DEAD box genes. DEAD box genes are part of a large family of proteins homologous to the eukaryotic transcription factor elF-4a. Most of these proteins are RNA-dependent ATPases and some of them have RNA helicase activity. This is the third yeast DEAD box protein that has been shown to be involved in rRNA assembly, but the only one required for the processing of 18S RNA. Mutants of the two other putative helicases, Spb4 and Drsl, both show processing defects in 25S rRNA maturation. In strains where Rrp3 is depleted, 35S precursor RNA is improperly processed. Cleavage normally occurs at sites A0O, Al and A2, but in the Rrp3 depletion stain cleavage occurs between A2 and B1. Rrp3 has been purified to homogeneity and has a weak RNA-dependent ATPase activity which is not specific for rRNA.
O'Day
C L
CL
Division of Biology 147-75, California Institute of Technology, Pasadena 91125, USA.
Chavanikamannil
F
F
Abelson
J
J
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D053487:DEAD-box RNA Helicases; D004794:Enzyme Repression; D005800:Genes, Fungal; D005804:Genes, Lethal; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017385:Sequence Homology; D014158:Transcription, Genetic
D012322:RNA Precursors; D012337:RNA, Ribosomal, 18S; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D012316:RNA Nucleotidyltransferases; D000251:Adenosine Triphosphatases; C101354:RRP3 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases