Prp43p is a DEAH-box spliceosome disassembly factor essential for ribosome biogenesis.
The known function of the DEXH/D-box protein Prp43p is the removal of the U2, U5, and U6 snRNPs from the postsplicing lariat-intron ribonucleoprotein complex. We demonstrate that affinity-purified Prp43p-associated material includes the expected spliceosomal components; however, we also identify several preribosomal complexes that are specifically purified with Prp43p. Conditional prp43 mutant alleles confer a 35S pre-rRNA processing defect, with subsequent depletion of 27S and 20S precursors. Upon a shift to a nonpermissive temperature, both large and small-ribosomal-subunit proteins accumulate in the nucleolus of prp43 mutants. Pulse-chase analysis demonstrates delayed kinetics of 35S, 27S, and 20S pre-rRNA processing with turnover of these intermediates. Microarray analysis of pre-mRNA splicing defects in prp43 mutants shows a very mild effect, similar to that of nonessential pre-mRNA splicing factors. Prp43p is the first DEXH/D-box protein shown to function in both RNA polymerase I and polymerase II transcript metabolism. Its essential function is in its newly characterized role in ribosome biogenesis of both ribosomal subunits, positioning Prp43p to regulate both pre-mRNA splicing and ribosome biogenesis.
Combs
D Joshua
DJ
Program in Cellular and Molecular Biology, University of Texas at Austin, 1 University Station #A4800, 2500 Speedway 2.448, Austin, Texas 78712, USA.
Nagel
Roland J
RJ
Ares
Manuel
M
Stevens
Scott W
SW
D002466:Cell Nucleolus / Q000235:genetics / Q000502:physiology; D019295:Computational Biology; D053487:DEAD-box RNA Helicases; D007438:Introns; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D020365:RNA Helicases / Q000235:genetics / Q000502:physiology*; D012318:RNA Polymerase I / Q000235:genetics / Q000502:physiology; D012319:RNA Polymerase II / 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; D012270:Ribosomes / Q000235:genetics* / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*
D012322:RNA Precursors; D012342:RNA, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D012319:RNA Polymerase II; D012318:RNA Polymerase I; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases