plant mitochondria
Hazle T & Bonen L 2007 Comparative analysis of sequences preceding protein-coding mitochondrial genes in flowering plants. Mol Biol Evol 24:1101-1112.
- we examined the nucleotide sequences preceding 23 mitochondrial protein-coding genes held in common by maize, rice, wheat, sugar beet, tobacco, Arabidopsis, and Brassica
- we observed broad variation in sequence similarity as illustrated by dot plot analysis
- ranging from a level rivaling that of coding sequences to complete absence of homology due to lineage-specific DNA rearrangements
- genes encoding ATP synthase subunits predominated in the latter category
- whereas ones encoding cytochrome c biogenesis proteins and NADH dehydrogenase subunits were primarily of the highly conserved type
- the switching of upstream regulatory sequences via DNA rearrangements has occurred frequently during flowering plant evolution
- genes encoding ATP synthase (atp) subunits are particularly dynamic
- the presence of additional upstream sequence copies within the intergenic spacers of plant mitochondrial genomes provides an opportunity for their future recruitment as regulatory elements as well as the de novo creation of transcripts which might even be translated into novel polypeptides
- this is a hallmark of certain types of cytoplasmic male sterility
- in this regard, it is notable that atp sequences (both regulatory and coding) are particularly frequent contributors to the creation of such ORFs
