Synthetic Lethality of Yeast slt Mutations with U2 Small Nuclear RNA Mutations Suggests Functional Interactions between U2 and U5 snRNPs That Are Important for Both Steps of Pre-mRNA Splicing

摘要: A genetic screen was devised to identify Saccharomyces cerevisiae splicing factors that are important for the function of 5′ end U2 snRNA. Six slt (stands synthetic lethality with U2) mutants were isolated on basis a snRNA mutation perturbs U2-U6 helix II interaction. SLT11 encodes new factor and SLT22 RNA-dependent ATPase RNA helicase (D. Xu, S. Nouraini, D. Field, J. Tang, Friesen, Nature 381:709–713, 1996). The remaining four mutations alleles previously identified genes: slt15, as prp17 (slt15/prp17-100), slt16/smd3-1, slt17/slu7-100, slt21/prp8-21. slt11-1 slt22-1 synthetically lethal in 3′ U6 snRNA, region affects II; however, slt17/slu7-100 slt21/prp8-21 not. This difference suggests latter two unlikely be involved interactions but rather specific Pairwise observed among (which first step splicing) several second-step factors, including slt15/prp17-100, prp16-1. Mutations loop 1 U5 is implicated alignment exons, slu4/prp17-2 slu7-1 Frank, B. Patterson, C. Guthrie, Mol. Cell. Biol. 12:5179–5205, 1992), well slt11-1, These same also interact genetically certain lie I regions structure. Our results suggest Slt protein may responsible coupling coordination reactions pre-mRNA splicing.