Talk abstracts

Talk on Saturday 09:00-09:20am submitted by Edward Turk

Yeast SUV3 Promotes Group I Intron Splicing by Recycling Co-factors from Excised Intron RNPs

Edward M. Turk (The Center for RNA Molecular Biology - Case Western Reserve University), Alycia Conway (Gilmour Academy), Mark G. Caprara (The Center for RNA Molecular Biology - Case Western Reserve University)

Abstract:
The yeast SUV3 gene encodes a SKI2-like DExH helicase that is an essential component of the mitochondrial degradosome (mtEXO) that functions in RNA processing and turnover. Defects in SUV3 result in loss of respiration and molecular phenotypes associated with impaired RNA degradation, such as accumulation of excised introns and high-molecular-weight, unprocessed transcripts. A perplexing phenotype associated with inactivation of SUV3 is decreased splicing of the aI5&beta and bI3 group I introns. We have analyzed a weak allele of SUV3 that is respiratory incompetent, accumulates excised aI5&beta intron, and is defective in splicing of aI5&beta and bI3. Each of these phenotypes can be partially rescued by over expression of MRS1, which encodes a protein co-factor essential for the in vivo splicing of aI5&beta and bI3. In addition, we use an in vitro splicing assay to demonstrate that recombinant Suv3p protein can recycle recombinant Mrs1p protein from excised aI5&beta. These results suggest a model whereby Suv3p acts to promote Mrs1p dissociation, leading to the degradation of the excised aI5&beta intron. Collectively, this prevents the sequestration of Mrs1p and thereby promotes splicing of aI5&beta and bI3. Furthermore, this work has generated a novel system whereby the mechanisms by which a DExH helicase can displace RNA-bound proteins can be investigated in the context of a native RNP substrate.

Keywords: Helicase, Splicing, Turnover