Genes for tRNAGly, tRNAHis, tRNALys, tRNAPhe, tRNASer and tRNATyr are encoded in Oenothera mitochondrial DNA

Abstract

The genes coding for tRNA^Gly, tRNA^His, tRNA^Lys, tRNA^Phe, tRNA^Ser and tRNA^Tyr have been identified in Oenothera mitochondrial DNA. Sequence analysis of these genes and their surrounding sequences are presented and compared with other known tRNA genes from plant mitochondria. All six deduced tRNA sequences can be folded into the classical cloverleaf structure model. Only the tRNA^His gene shows high homology with the corresponding chloroplast gene and thus appears to be derived from a transfer event of chloroplast sequences into the mitochondrial genome. The sequences surrounding this gene, however, show little similarity with the chloroplast genome. The other five deduced tRNAs display a much lower similarity with their chloroplast counterparts and thus appear to be genuine mitochondrial tRNAs. These tRNAs are highly conserved between monocots and dicots with maximally three nucleotides differing between the Oenothera sequences and their wheat homologues. A purine-rich sequence is found upstream of each tRNA gene in Oenothera, similar to wheat mitochondrial tRNA genes, that could be involved in transcription signalling.