THE NADH DEHYDROGENASE SUBUNIT-7 GENE IS INTERRUPTED BY 4 GROUP-II INTRONS IN THE WHEAT MITOCHONDRIAL GENOME

We have characterized a wheat mitochondrial gene, designated nad7, cap able of encoding a 394-amino acid subunit of the respiratory chain NAD H dehydrogenase complex. It contains four introns possessing group II features and their positions differ from those in both the liverwort m itochondrial nad7 pseudogene and the nuclear gene encoding the homolog ues 49 kDa subunit of complex I in Neurospora, The derived amino acid sequence of the wheat nad7 gene is strongly conserved relative to its nuclear or organellar counterparts in other organisms. C-to-U type RNA editing, which is observed at 32 positions within the coding region o f wheat nad7 transcripts, strengthens protein sequence similarity. RNA editing is also predicted to improve base-pairing within the domain V /VI regions of all four introns.