SRA

Transcription and pre-mRNA splicing are coupled to promote gene expression and regulation. However, mechanisms by which transcription and splicing influence each other are still under investigation. The ATPase Prp5p is required for pre-spliceosome assembly and splicing proofreading at the branch-point region. From an open UV mutagenesis screen for genetic suppressors of prp5 defects and subsequent targeted testing, we identify components of the TBP-binding module of the Spt–Ada–Gcn5 Acetyltransferase (SAGA) complex, Spt8p and Spt3p. Spt8? and spt3? rescue the cold-sensitivity of prp5-GAR allele, and prp5 mutants restore growth of spt8? and spt3? strains on 6-azauracil. By chromatin immunoprecipitation (ChIP), we find that prp5 alleles decrease recruitment of RNA polymerase II (Pol II) to an intron-containing gene, which is rescued by spt8?. Further ChIP-seq reveals that global effects on Pol II-binding is mutually rescued by prp5 mutant and spt8?. Inhibited splicing caused by prp5-GAR is also restored by spt8?. In vitro assay indicates that Prp5p directly interacts with Spt8p, but not Spt3p. We demonstrate that Prp5p's splicing proofreading is modulated by Spt8p and Spt3p. Therefore, this study reveals that interactions between the TBP-binding module of SAGA and the spliceosomal ATPase Prp5p mediate a balance between transcription initiation/elongation and pre-spliceosome assembly. Overall design: Examining the Pol II profile in WT and Spt8? strains with Prp5-WT or Prp5-GAR mutation at 16°C and 30°C