Sequence and organization of a 7.2 kb region of wheat mitochondrial DNA containing the large subunit (26S) rRNA gene

Abstract

We report the sequence of a 7.2 kilobase pair DNA fragment containing a copy of the wheat mitochondrial gene (rrn26) that encodes the mitochondrial large-subunit ribosomal RNA (26S rRNA). The mature 26S rRNA was determined by direct RNA sequencing to be 3467 nucleotides long, and to share a 5'-terminal pentanucleotide (5'-AUCAU), thought to be important in post-transcriptional processing, with the wheat mitochondrial small-subunit (18S) rRNA. Two other prominent features of the sequence were noted. First, upstream of rrn26 are located two tandem copies of a 70 base pair element containing a putative mitochondrial promoter motif (TCGTATAAAAA). Second, downstream of rrn26 is a sequence element that, if transcribed, would produce an RNA with a secondary structure resembling that of tRNAs but differing sufficiently from the latter structure to preclude any transcript from functioning normally in translation. These upstream and downstream sequence elements may play a role in the expression of rrn26 in wheat mitochondria.

Ribosomal protein L10 is encoded in the mitochondrial genome of many land plants and green algae

“…Yellow shading indicates compensatory changes in E. coli that maintain base pairing in stem regions. Nucleotide coordinates are shown for Triticum aestivum mitochondrial 26s rRNA [56] and in parentheses for E. coli 23s rRNA [34,35]. …”