Poster abstracts
Poster number 29 submitted by Kim Delaney
Trans-Splicing and the Co-Evolution of SNF Proteins with their RNA Targets
Rex Meade Strange (University of Southern Indiana), L. Peyton Russelburg (University of Southern Indiana), Kimberly J. Delaney (University of Southern Indiana)
Abstract:
Although the mechanism of pre-mRNA splicing has been well characterized, the evolution of spliceosomal proteins is poorly understood. The U1A/U2Bʺ/SNF family of RNA binding spliceosomal proteins participates in both the U1 and U2 small interacting nuclear ribonucleoproteins (snRNPs). Both snRNPs play a role in cis-slpicing, the predominant mode of pre-mRNA splicing in many eukaryotic organisms. However, some species are capable of trans-splicing, an alternative mechanism that does not employ the U1 snRNP. In SNF phylogenetic analysis of protostome species, we observed a correlation between trans-splicing species (nematodes and platyhelminths) and increased phylogenetic branch lengths of the U1A/U2Bʺ/SNF protein family. We found that nematodes (~70-80% of pre-mRNAs are trans-spliced) have experienced higher rates of SNF sequence evolution than arthropods (predominantly cis-spliced) at both the nucleotide and amino acid levels. We mapped substitutions to functionally important regions of the SNF protein, specifically to amino acids that are predicted to disrupt protein:RNA and protein:protein interactions. Finally, we investigated SNF’s RNA targets: the U1 and U2 snRNAs. Both exhibit reduced sequence conservation in comparison to that observed in arthropods, suggesting the RNAs have co-evolved with SNF in order to maintain the necessarily high affinity interaction that has been characterized in other species.
Keywords: Trans-Splicing, RRM, U1ASNF