RNA EDITING IN PLANT-MITOCHONDRIA

In plant mitochondria, RNA editing involves the conversion of specific Cs in the genomic sequence into Us in the mRNA. There are a few reverse conversions. A majority of the editing sites are in coding regions. After RNA editing, plant mitochondria use the universal genetic code if one considers the RNA message. Considering the deduced protein sequence, RNA editing is a correction mechanism. RNA editing is a post-transcriptional process, active during the maturation of the mRNA. It has no evident polarity. At the translation level, the mRNAs are likely to be fully edited and to code for a unique protein. RNA editing is a recently discovered process that may have a number of consequences on our understanding of the regulation of mitochondrial gene expression. The main problems to be solved are the identification of the template information necessary for the specificity of RNA editing and its biochemical mechanism. Comparative studies could perhaps answer the question of the evolutionary origin of RNA editing, which is discussed to be a remnant of the RNA world.