Mutational analysis of U1 function in Schizosaccharomyces pombe: pre-mRNAs differ in the extent and nature of their requirements for this snRNA in vivo.

摘要: The U1 snRNP is known to play a critical role in spliceosome assembly, at least part through base pairing of its RNA moiety the substrate, but many details remain be elucidated. To further dissect snRNA function, we have analyzed 14 single point mutations six nucleotides complementary 5' splice site for their effects on growth and splicing fission yeast Schizosaccharomyces pombe. Three four alleles previously found support Saccharomyces cerevisiae are lethal S. pombe, implying more end yeast. Furthermore, comparison phenotypes individual nucleotide substitutions suggests that two yeasts use different strategies modulate extent between site. importance function pombe underscored by lethality several mutants not examined cerevisiae. In total, only three complement gene disruption, these strains temperature-sensitive growth. Each viable mutant was tested impaired introns. Among these, second intron cdc2 (cdc2-I2) showed dramatic accumulation linear precursor. Notably, cdc2-I2 spliced inefficiently even cells containing wild-type U1, due presence stable hairpin encompassing Although no discernible effect pre-U6, significant unspliced observed metabolic depletion experiment. Taken together, observations indicate repertoire activities used varying extents pre-mRNAs