A dual role for BBP/ScSF1 in nuclear pre-mRNA retention and splicing.
The MSL5 gene, which codes for the splicing factor BBP/ScSF1, is essential in Saccharomyces cerevisiae, yet previous analyses failed to reveal a defect in assembly of (pre)-spliceosomes or in vitro splicing associated with its depletion. We generated 11 temperature-sensitive (ts) mutants and one cold-sensitive (cs) mutant in the corresponding gene and analyzed their phenotypes. While all mutants were blocked in the formation of commitment complex 2 (CC2) at non-permissive and permissive temperature, the ts mutants showed no defect in spliceosome formation and splicing in vitro. The cs mutant was defective in (pre)-spliceosome formation, but residual splicing activity could be detected. In vivo splicing of reporters carrying introns weakened by mutations in the 5' splice site and/or in the branchpoint region was affected in all mutants. Pre-mRNA leakage to the cytoplasm was strongly increased (up to 40-fold) in the mutants. A combination of ts mutants with a disruption of upf1, a gene involved in nonsense-mediated decay, resulted in a specific synthetic growth phenotype, suggesting that the essential function of SF1 in yeast could be related to the retention of pre-mRNA in the nucleus.
Rutz
B
B
EMBL, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Séraphin
B
B
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D010957:Plasmids; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*; D013696:Temperature; D014157:Transcription Factors
D004268:DNA-Binding Proteins; C409040:MSL5 protein, S cerevisiae; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C491516:SF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate