Prp5-Spt8/Spt3 interaction mediates a reciprocal coupling between splicing and transcription

Area of Science:

• Molecular Biology
• Gene Expression Regulation
• RNA Splicing Mechanisms

Background:

• Transcription and pre-mRNA splicing are coupled processes crucial for gene expression.
• The spliceosomal ATPase Prp5p is essential for pre-spliceosome assembly and splicing proofreading.
• Mechanisms linking transcription and splicing remain incompletely understood.

Purpose of the Study:

• To identify genetic factors that suppress defects in the ATPase Prp5p.
• To elucidate the interplay between transcription initiation/elongation and pre-spliceosome assembly.
• To investigate the role of the SAGA complex in coupling transcription and splicing.

Main Methods:

• Open UV mutagenesis screen for genetic suppressors of prp5 defects.
• Chromatin immunoprecipitation (ChIP) and ChIP-seq to assess RNA polymerase II binding.
• In vitro interaction assays.
• Genetic analysis of mutant strains.

Main Results:

• Components of the SAGA complex, Spt8p and Spt3p, were identified as suppressors of prp5 defects.
• prp5 mutants and spt8Δ/spt3Δ mutants exhibit reciprocal genetic interactions.
• Spt8p rescues defects in RNA polymerase II recruitment and splicing caused by prp5 alleles.
• Prp5p directly interacts with Spt8p, and both Spt8p and Spt3p modulate Prp5p's splicing proofreading activity.

Conclusions:

• The TBP-binding module of the SAGA complex interacts with the spliceosomal ATPase Prp5p.
• This interaction mediates a balance between transcription and pre-spliceosome assembly.
• SAGA complex components play a regulatory role in the coupling of transcription and splicing.