The splicing ATPase prp43p is a component of multiple preribosomal particles.
Prp43p is a putative helicase of the DEAH family which is required for the release of the lariat intron from the spliceosome. Prp43p could also play a role in ribosome synthesis, since it accumulates in the nucleolus. Consistent with this hypothesis, we find that depletion of Prp43p leads to accumulation of 35S pre-rRNA and strongly reduces levels of all downstream pre-rRNA processing intermediates. As a result, the steady-state levels of mature rRNAs are greatly diminished following Prp43p depletion. We present data arguing that such effects are unlikely to be solely due to splicing defects. Moreover, we demonstrate by a combination of a comprehensive two-hybrid screen, tandem-affinity purification followed by mass spectrometry, and Northern analyses that Prp43p is associated with 90S, pre-60S, and pre-40S ribosomal particles. Prp43p seems preferentially associated with Pfa1p, a novel specific component of pre-40S ribosomal particles. In addition, Prp43p interacts with components of the RNA polymerase I (Pol I) transcription machinery and with mature 18S and 25S rRNAs. Hence, Prp43p might be delivered to nascent 90S ribosomal particles during pre-rRNA transcription and remain associated with preribosomal particles until their final maturation steps in the cytoplasm. Our data also suggest that the ATPase activity of Prp43p is required for early steps of pre-rRNA processing and normal accumulation of mature rRNAs.
Lebaron
Simon
S
Laboratoire de Biologie Moléculaire Eucaryote, UMR5099 CNRS-Université Paul Sabatier, IFR109, 118 route de Narbonne, 31062 Toulouse cedex 09, France.
Froment
Carine
C
Fromont-Racine
Micheline
M
Rain
Jean-Christophe
JC
Monsarrat
Bernard
B
Caizergues-Ferrer
Michèle
M
Henry
Yves
Y
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D013058:Mass Spectrometry; D019154:Protein Splicing; D020365:RNA Helicases / Q000235:genetics* / Q000378:metabolism; D012318:RNA Polymerase I / Q000235:genetics / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000235:genetics* / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D012322:RNA Precursors; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012318:RNA Polymerase I; D000251:Adenosine Triphosphatases; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases