SAGA‐mediated acetylation interacts with Prp5 ATPase activity in pre‐mRNA splicing (940.1)

Abstract

Regulation of gene expression occurs at multiple levels, including the removal of non‐coding sequences from protein‐coding pre‐messenger RNA transcripts, commonly known as RNA splicing. Correct gene expression requires high fidelity in pre‐mRNA splicing, as up to 15% of mutations leading to disease result in aberrant pre‐mRNA splicing. Though previously thought of as biologically distinct processes, recent studies have shown there is a complex interplay between transcription and pre‐mRNA splicing, however, the regulation underlying this coordination remains unclear. Using the budding yeast Saccharomyces cerevisiae, we have identified interactions between components of the SAGA (Spt/Ada/Gcn5/Ada) transcriptional coactivator complex and the ATP‐dependent spliceosomal DEAD‐box protein Prp5. Prp5 plays a critical role in mediating ATP‐dependent RNA remodeling in splicing, though its precise role in transcription or chromatin remodeling is unclear. Deletion of genes encoding components of the SAGA complex required for histone acetylation, including the histone acetyltransferase (HAT) gcn5, bypasses the Prp5 ATPase requirement in splicing. This regulation is specific to HAT components of the SAGA complex: deletion of non‐HAT SAGA components, or non‐SAGA histone acetyltransferases does not rescue the Prp5 ATPase mutant phenotype. The interaction of Prp5 ATPase activity with Gcn5 also involves chromatin, as deletion of histone targets acetylated by Gcn5 also bypasses the Prp5 ATPase requirement. Analysis of gene expression using splicing‐specific microarrays reveals that deletion of gcn5 results in improved splicing of a subset of genes dependent on Prp5 ATPase activity for splicing. These data suggest that Prp5 may coordinate co‐transcriptional splicing through its interaction with chromatin and chromatin‐interacting proteins, and indicates a possible role of chromatin and chromatin‐interacting proteins in regulating U2 snRNP assembly or structure.Grant Funding Source: Supported by NIH GM05474 and NIH K12 GM068524‐10