Modulation of RNA editing efficiencies to investigate protein function and homeostasis in the mitochondria of plants

• Applicant: Dr. Nils Rugen
• Subject Area: Plant Physiology ; Plant Biochemistry and Biophysics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559930175

Transcripts of organellar genes may be edited in plants. As a result, the encoded information of the transcripts (the RNAs) no longer corresponds exactly to the information encoded by the respective gene segments at the DNA level. There are numerous editing sites in the organelles of plants, especially in the mitochondria, but also in the chloroplasts. The editing sites are defined by specificity factors. In many cases, RNA editing leads to altered amino acid sequences of the corresponding proteins. However, the biological background of this process is still not understood. In many but not all cases, RNA editing leads to increased sequence similarity of proteins compared to those from other groups of organisms in which no RNA editing occurs. It has been interpreted that RNA editing may serve to compensate for unfavorable mutations that have become established during evolution. However, there is also evidence that RNA editing in the organelles of plant cells represents a regulatory level of protein biosynthesis. Of particular interest in this context are partially edited transcripts, which are known to be translated into proteins in some cases. As a result, several proteoforms of a protein are derived from individual genes. In the proposed project, proteins derived from incompletely edited transcripts will be identified and quantified using the latest methods of the "deep proteomics" strategy. Subsequently, the functions and fates of these proteins will be systematically traced. In order to better investigate this question, we will work with Arabidopsis mutants that are characterized by a reduced editing rate, so that proteins derived from non-edited RNAs can be expected in increased quantities. There are indications that these proteins are rapidly degraded. The lifespan of such proteins will therefore be determined experimentally. In some cases, however, it has been shown that proteins derived from partially edited RNAs are incorporated into protein complexes (Rugen et al. 2024, Plant Physiology 195, pp 1180-1199). Corresponding protein complexes are to be characterized with regard to their assembly pathway, their stability and their function. The proposed experiments are suitable for further elucidating the biological significance of RNA editing in plant organelles. The results will contribute to a deeper understanding of the plant energy metabolism.

• DFG Programme: Research Grants