Symmetrical transcription in the tRNA region of the mitochondrial genome of Saccharomyces cerevisiae.

The occurrence of discrete transcripts originating from the non-coding strand of the yeast mitochondrial genome is described. The region under investigation is localized in the large tRNA gene cluster between the LSU ribosomal RNA and OXI 1 genes. The transcripts originating from the non-coding strand were detected in a wild-type strain and in a rho- mutant. Their size range includes transcripts of about 2000 nucleotides able to accommodate more than one "anti-tRNA". In some cases their extremities can be mapped near highly-conserved nonanucleotides that could function as origins of transcription. The involvement of the tRNA-processing machinery in the cleavage of these transcripts is also hypothesized.