TRANSCRIPTION INITIATION SITES FOR THE POTATO MITOCHONDRIAL GENE CODING FOR SUBUNIT-9 OF ATP SYNTHASE (ATP9)

The potato mitochondrial atp9 gene has a simple expression pattern. To determine where transcription initiates, primary mitochondrial RNAs w ere labeled by in vitro capping and hybridized to the 5' flanking sequ ences of the atp9 gene. A single transcription initiation region was i dentified. Primer extension and nuclease S1 protection analyses were u sed to precisely map the transcript 5' termini in this region. These r esults indicate that transcription initiates at 121-128 bp upstream of the atp9 open reading frame, in a sequence which does not present any homology with proposed consensus sequences for plant mitochondrial pr omoters. Nuclease S1 protection were also used to map 3' termini 67-71 nucleotides downstream of a putative single-stem loop structure.