The pea mitochondrial atp6:: RNA editing and similarity of presequences in the Vicieae tribe

The atp6 gene has been identified as a single-copy sequence in the mitochondrial genome of the pea. An unexpected finding concerns the atp6 5' extension which is known to be poorly conserved at the sequence level, even between closely related plant species. We have shown that the presequences of ATP6 from the pea and other species belonging to the Vicieae tribe of Fabaceae (broad bean, hairy vetch) share a sequence similarity which extends to long 5' untranslated transcript termini. The reason for the observed conservation is not clear but may simply reflect the close phylogenetic relationship of species from the Vicieae tribe. The result of editing analysis indicates the occurrence of fully and partially edited transcripts of atp6 in the pea mitochondria. The majority of the editing sites are targeted to the last transmembrane domain of the pea ATP6, important in proton translocation and interactions with other subunits of ATP synthase.