The PPR-related splicing cofactor MSP1/EMB1025 protein, encoded by At4g20090, encode an essential protein that is required for the splicing ofnad1intron 1 and for the biogenesis of complex I in Arabidopsis mitochondria

• DOI: 10.1101/615856
• Publication Date: 2019-04-23T04:55:15Z
• Authors: Corinne Best; Michal Zmudjak; Oren Ostersetzer-...
• Keywords: 0301 basic medicine; 03 medical and health sciences

AbstractGroup II introns are particularly plentiful within plant mitochondrial genomes (mtDNAs), where they interrupt the coding-regions of many organellar genes, especialy within complex I (CI) subunits. Their splicing is essential for the biogenesis of the respiratory system and is facilitated by various protein-cofactors that belong to a diverse set of RNA-binding cofactors. These including maturases, which co-evolved with their host-introns, and varioustrans-acting factors, such as members of the pentatricopeptide-repeat (PPR) protein family. The genomes of angiosperms contain hundreds ofPPR-related genes that are postulated to reside within the organelles and affect diverse posttranscriptional steps, such as editing, RNA-stability and processing or translation. Here, we report the characterization of MSP1 (Mitochondria Splicing PPR-factor 1; also denoted as EMB1025), which plays a key role in the processing ofnad1pre-RNAs in Arabidopsis mitochondria. Mutations inMSP1gene-locus (At4g20090) result in early embryonic arrest. To analyze the putative roles of MSP1 in organellar RNA-metabolism we used a modified embryo-rescue method, which allowed us to obtain sufficient plant tissue for the analysis of the RNA and protein profiles associated withmsp1mutants. Our data indicate that MSP1 is essential for thetrans-splicing ofnad1intron 1 in Arabidopsis mitochondria. Accordingly,msp1mutants show CI biogenesis defects and reduced respiratory-mediated functions. These results provide with important insights into the roles of nuclear-encoded factors during early plant development, and contribute to our limited understanding of the importance of RNA-maturation and splicing in plant mitochondria during early embryogenesis.