Partial characterization of the gene coding for subunit IV of soybean mitochondrial NADH dehydrogenase

By using the spinach chloroplast atpE gene (epsilon-subunit coding gene) as a probe we have isolated, from a soybean mitochondrial DNA library, a sequence containing a 405 base-pairs (bp) open-reading frame (ORF). This ORF, which is unique in the soybean mitochondrial genome, is probably part of an exon of the gene coding for subunit IV of the NADH dehydrogenase complex. The predicted protein shows 42% sequence similarity with the C-terminal region the Aspergillus nidulans NAD4 protein. The gene is split by a class II intron which is larger than 1,950 bp. Transcription analysis revealed a single 2,200 nucleotide long transcript which does not contain the intron sequence.