A GENE INVOLVED IN THE BIOGENESIS OF CYTOCHROMES IS CO-TRANSCRIBED WITH A RIBOSOMAL-PROTEIN GENE IN WHEAT MITOCHONDRIA

Sequence analysis of a transcribed region of the wheat mitochondrial ( mt) genome revealed two open reading frames (orfs) coding for proteins of 589 and 174 amino acids. Both genes are co-transcribed in a 2.6-kb RNA. The largest orf codes for a hydrophobic protein which bears simi larity to a bacterial protein involved in the biogenesis of c-type cyt ochromes. Its corresponding RNA sequence is fully edited at 34 positio ns. The second orf encodes a protein homologous to the amino-terminal third of E. coli ribosomal protein S1, corresponding to the ribosome-b inding domain of this protein. Its RNA sequence is edited at four posi tions, one of the edits creating a stop codon. The presence of both pr oteins in wheat mitochondria was demonstrated using specific antibodie s raised against fusion proteins obtained in E. coli from the correspo nding cDNAs.