ASSAYS FOR INVESTIGATING RNA EDITING IN PLANT-MITOCHONDRIA

In plant organelles transcripts are modified posttranscriptionally by RNA editing. This modification process changes almost every protein-co ding RNA at specific cytidine and uridine positions. Therefore, mitoch ondrially encoded protein sequences differ from the genomically fixed information and show, after editing, a higher conservation. To investi gate this unusual processing step in plant mitochondria, several assay s have been developed. However, compared with the progress made in oth er RNA editing fields, knowledge about the factors involved in plant m itochondrial editing is limited. One reason for this is the lack of a reliable in vitro system for mitochondria. To reveal the biochemical n ature of the RNA editing reaction in plant mitochondria, we developed an in vitro system by which we were able to show that cytidine is spec ifically modified to uridine by a deamination or transamination proces s. Here we describe the development of a pea in vitro system and discu ss assays to follow the editing process. (C) 1998 Academic Press.