Dependence of pre-mRNA introns on PRP17, a non-essential splicing factor: implications for efficient progression through cell cycle transitions.
Saccharomyces cerevisiae PRP17 (CDC40) encodes a second-step pre-mRNA splicing factor with a role in cell division. The functions of Prp17 in specific cell cycle transitions were examined using temperature-sensitive alleles in arrest/release experiments. We find that G(1)/S and G(2)/M transitions depend on Prp17. G(1)-synchronized prp17::LEU2 cells arrest at non-permissive temperatures as unbudded haploid cells with low levels of CLN1, CLB5 and RNR1 transcripts. This indicates a Prp17 execution point at or prior to Start. Reduced levels of alpha-tubulin protein, a mitotic spindle component, underlie the benomyl sensitivity of prp17 mutants and possibly their G(2)/M arrest. Splicing of TUB1 and TUB3 transcripts, which encode alpha-tubulin, was analyzed in prp17 and other second-step factor mutants. TUB1 splicing is inefficient in prp17, prp16 and prp22, and marginally affected in prp18, slu7-1 and psf1-1. TUB3 splicing is similarly affected. In vitro splicing with TUB3 pre-mRNA demonstrates a compromised second step in prp17::LEU2 extracts, implicating a direct role for Prp17 in its efficient splicing. Genomic replacement of an intronless TUB1 gene relieves the benomyl sensitivity of prp17 mutants; however, they remain temperature sensitive, implying multiple limiting factors for mitosis. The data suggest that integration of splicing with the cell cycle is important for G(1)/S and G(2)/M transitions.
Chawla
Geetanjali
G
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
Sapra
Aparna K
AK
Surana
Uttam
U
Vijayraghavan
Usha
U
D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D016193:G1 Phase / Q000502:physiology; D016195:G2 Phase / Q000502:physiology; D007438:Introns / Q000235:genetics*; D009154:Mutation; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus / Q000235:genetics / Q000502:physiology; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014404:Tubulin / Q000235:genetics
C093570:CDC40 protein, S cerevisiae; C082721:CLN2 protein, S cerevisiae; D018797:Cell Cycle Proteins; D016213:Cyclins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin