In vitro processing of mitochondrial and plastid derived tRNA precursors in a plant mitochondrial extract

A lysate of purified mitochondria of the higher plant Oenothera processes in vitro synthesized tRNA precursors to the mature tRNA size. In vitro synthesized transcripts containing genuine plant mitochondrial tRNAs and analogous RNAs from mitochondrial loci with plastid derived tRNA sequences are accurately processed by an RNAase P-like activity to yield the mature 5'-terminus. A four nucleotide deletion in the anticodon stem-loop structure, however, prevents processing. The results show that in vitro transcripts containing tRNAs from sequence fragments of plastid origin integrated in plant mitochondrial genomes can be processed correctly in plant mitochondria, if tRNA sequences and structures are intact.