Mitochondrial rps14 is a transcribed and edited pseudogene in Arabidopsis thaliana

Abstract

We have isolated and analysed a 2 kb region of the mitochondrial genome of Arabidopsis thaliana (Columbia) showing a high level of nucleotide identity with the mitochondrial (mt) rps14 small-subunit ribosomal protein gene from Oenothera berteriana and Vicia faba, as well as with an open reading frame (ORF) located upstream of the nad3 locus in O. berteriana. The rps14 locus is present as a single copy in the A. thaliana mt genome and has a translational stop codon located near the initiation codon, as well as a deletion of one nucleotide that disturbs the coding sequence. The cloning and sequencing of nine amplified mt rps14 cDNAs clearly demonstrated that this gene is transcribed and that the mRNA precursors are edited at three positions, all involving C-to-U conversions. No editing events changing the stop codon and restoring the correct coding sequence were witnessed within the 9 individual cDNA clones. Therefore, we conclude that the single rps14 sequence of the mitochondrial genome from A. thaliana is in fact a pseudogene that is transcribed and edited but not translated.

A single nuclear transcript encoding mitochondrial RPS14 and SDHB of rice is processed by alternative splicing: Common use of the same mitochondrial targeting signal for different proteins

“…The nucleotide and deduced amino acid sequence comparison with those from other plant species showed that the rice rpl5 gene retains an intact ORF, whereas the original reading frame of the rps14 is interrupted by nucleotide deletions at four positions. A similar gene disruption has been reported in Arabidopsis (20,21) and potato (22), but the nucleotide deletion sites are different among the three plants. RNA gel blot analysis proved that the rps14 sequence was transcribed (see Fig.…”

“…The presence of rps14 gene in the mitochondrial genome has been reported from lower plants such as liverwort (3) and chlorophyte alga (16). Among the higher plants, intact rps14 genes have been found in the mitochondrial genome of broadbean (17), Oenothera (18), and rapeseed (19), whereas rps14 is present as a pseudogene in Arabidopsis (20,21) and potato mitochondria (22). The nucleotide and deduced amino acid sequence comparison with those from other plant species showed that the rice rpl5 gene retains an intact ORF, whereas the original reading frame of the rps14 is interrupted by nucleotide deletions at four positions.…”

A single homogeneous form of ATP6 protein accumulates in petunia mitochondria despite the presence of differentially edited atp6 transcripts.

“…We believe this is unlikely because editing is known to occur in plant mitochondrial pseudogene transcripts that contain stop codons near the initiation codon (Schuster and Brennicke, 1991a;Aubert et al, 1992).…”

Organization of repetitive DNAs and the genomic regions carrying ribosomal RNA, cob, and atp9 genes in the cucurbit mitochondrial genomes

“…3B, Table 3). This arrangement of the rpl5-pseudo-rps14-cob is conserved in both Arabidopsis and potato (Aubert et al 1992;Quiaeones et al 1996); other plants (such as Pisum sativum and Brassica napus) possess the rpl5-rps14-cob cluster with a functional rps14, and these genes are cotranscribed (Ye et al 1996;Hoffmann et al 1999). Regions of strong sequence similarities in the intergenic regions were evident in squash and watermelon, with a specific region of high similarity adjacent to cob present in all four cucurbits (Fig.…”

“…The rpl5-rps14-cob and rrn5-rn18 operons are conserved in most plants (Aubert et al 1992;Ye et al 1993;Quiaeones et al 1996;Hoffmann et al 1999), including squash and watermelon, but are rearranged in Cucumis (Fig. 4B).…”