The splicing factor Prp43p, a DEAH box ATPase, functions in ribosome biogenesis.
Biogenesis of the small and large ribosomal subunits requires modification, processing, and folding of pre-rRNA to yield mature rRNA. Here, we report that efficient biogenesis of both small- and large-subunit rRNAs requires the DEAH box ATPase Prp43p, a pre-mRNA splicing factor. By steady-state analysis, a cold-sensitive prp43 mutant accumulates 35S pre-rRNA and depletes 20S, 27S, and 7S pre-rRNAs, precursors to the small- and large-subunit rRNAs. By pulse-chase analysis, the prp43 mutant is defective in the formation of 20S and 27S pre-rRNAs and in the accumulation of 18S and 25S mature rRNAs. Wild-type Prp43p immunoprecipitates pre-rRNAs and mature rRNAs, indicating a direct role in ribosome biogenesis. The Prp43p-Q423N mutant immunoprecipitates 27SA2 pre-rRNA threefold more efficiently than the wild type, suggesting a critical role for Prp43p at the earliest stages of large-subunit biogenesis. Consistent with an early role for Prp43p in ribosome biogenesis, Prp43p immunoprecipitates the majority of snoRNAs; further, compared to the wild type, the prp43 mutant generally immunoprecipitates the snoRNAs more efficiently. In the prp43 mutant, the snoRNA snR64 fails to methylate residue C2337 in 27S pre-rRNA, suggesting a role in snoRNA function. We propose that Prp43p promotes recycling of snoRNAs and biogenesis factors during pre-rRNA processing, similar to its recycling role in pre-mRNA splicing. The dual function for Prp43p in the cell raises the possibility that ribosome biogenesis and pre-mRNA splicing may be coordinately regulated.
Leeds
Nina B
NB
Department of Molecular Genetics and Cell Biology, University of Chicago, 920 E. 58th St., Chicago, Illinois 60637, USA.
Small
Eliza C
EC
Hiley
Shawna L
SL
Hughes
Timothy R
TR
Staley
Jonathan P
JP
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D053487:DEAD-box RNA Helicases; D009154:Mutation; D020365:RNA Helicases / Q000235:genetics / Q000502:physiology*; D012322:RNA Precursors / Q000235:genetics* / Q000502:physiology; D012326:RNA Splicing / Q000235:genetics* / Q000502:physiology; D012342:RNA, Small Nuclear / Q000235:genetics / Q000502:physiology; D020537:RNA, Small Nucleolar / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics* / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*
D012322:RNA Precursors; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases