Pettitt, Jonathan, Soto-Martin, Eva, Eiljers, Peter, Elmassoudi, Haitem, Wenzel, Marius, Muller, Berndt, Connolly, Bernadette, Fasimoye, Rotimi, Spencer, Rosie
[
International Worm Meeting,
2021]
We are investigating spliced leader (SL) trans-splicing and its key RNA and protein components as potential anthelmintic targets, using Caenorhabditis elegans as a model system. SL trans-splicing is an essential process in nematode gene expression that facilitates translation by replacement of the 5' untranslated region of most mRNAs with the spliced leader 1 (SL1). The splicing reaction involves an interaction between the SL1 snRNP, the nascent pre-mRNA and the spliceosome. Although SL trans-splicing was discovered more than 30 years ago, we know little about the molecular mechanism(s) by which this is achieved. To address this, we have carried out a comprehensive molecular characterisation of the SL1 snRNP. This work expands and refines our understanding of the proteins involved in SL1 trans-splicing: we have analysed factors co-immunoprecipitating with the SL1-specific protein SNA-1, giving us insight into the interaction of the SL1 snRNP with the spliceosome. Proteins critical for SL1 trans-splicing were identified using established RNAi-based qPCR and gfp-reporter gene assays (https://doi.org/10.1093/nar/gkx500). This led to the identification of a novel, essential trans-splicing factor termed SNA-3. SNA-3 is a highly conserved, nematode specific protein containing NADAR domains, which have been linked to NAD/ADP-ribose metabolism and may have N-glycosidase activity. SNA-3 interacts with several highly-conserved proteins associated with RNA processing including the CBC-ARS2 complex components NCBP-1 and SRRT/ARS2 involved in co-transcriptional determination of transcript fate. Together, these observations implicate SNA-3 in key steps linking SL1 trans-splicing to the transcriptional control of gene expression. The identification of another essential, nematode-specific protein involved in SL1trans-splicing strengthens the hypothesis that the acquisition of SL trans-splicing requires the evolution of novel machinery required to modify the activity of the spliceosome. The novelty of these proteins makes them ideal targets for the development of new anthelmintics.