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The RNA editing pattern of cox2 mRNA is affected by point mutations in plant mitochondria.

Castandet B, Araya A - PLoS ONE (2011)

Bottom Line: It has been reported that a short region surrounding the target C forms the cis-recognition elements, but individual residues on it do not play similar roles for the different editing sites.We found that four different recognition patterns can be distinguished: (a) +1 dependency, (b) -1 dependency, (c) +1/-1 dependency, and (d) no dependency on nearest neighbor residues.Our data suggest that the complex response observed for cox2 mRNA may be a consequence of the fate of the transcript during mitochondrial gene expression.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, MCMP- UMR5234, Centre National de la Recherche Scientifique and Université Bordeaux Segalen. Bordeaux, France.

ABSTRACT
The mitochondrial transcriptome from land plants undergoes hundreds of specific C-to-U changes by RNA editing. These events are important since most of them occur in the coding region of mRNAs. One challenging question is to understand the mechanism of recognition of a selected C residue (editing sites) on the transcript. It has been reported that a short region surrounding the target C forms the cis-recognition elements, but individual residues on it do not play similar roles for the different editing sites. Here, we studied the role of the -1 and +1 nucleotide in wheat cox2 editing site recognition using an in organello approach. We found that four different recognition patterns can be distinguished: (a) +1 dependency, (b) -1 dependency, (c) +1/-1 dependency, and (d) no dependency on nearest neighbor residues. A striking observation was that whereas a 23 nt cis region is necessary for editing, some mutants affect the editing efficiency of unmodified distant sites. As a rule, mutations or pre-edited variants of the transcript have an impact on the complete set of editing targets. When some Cs were changed into Us, the remaining editing sites presented a higher efficiency of C-to-U conversion than in wild type mRNA. Our data suggest that the complex response observed for cox2 mRNA may be a consequence of the fate of the transcript during mitochondrial gene expression.

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Editing status of cox2 transcripts carrying combined −1 or +1 mutations.Gray bars represent the editing efficiency on the wild type transcripts. (A) Editing status of mRNA from the combined −1 mutant (blue bars). (B) Editing status of mRNA from the combined +1 mutant (red bars). The sites C77, C259 and C385 not mutated in the −1 or +1 combined constructs are shown by light gray bars. The results presented are representative from at least two separate experiments. Editing efficiency variations in replicates was lower than 10%.
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pone-0020867-g002: Editing status of cox2 transcripts carrying combined −1 or +1 mutations.Gray bars represent the editing efficiency on the wild type transcripts. (A) Editing status of mRNA from the combined −1 mutant (blue bars). (B) Editing status of mRNA from the combined +1 mutant (red bars). The sites C77, C259 and C385 not mutated in the −1 or +1 combined constructs are shown by light gray bars. The results presented are representative from at least two separate experiments. Editing efficiency variations in replicates was lower than 10%.

Mentions: In a second set of experiments, either the −1 or the +1 neighbor residues from all editing sites, with the exception of C77, C259 and C385, were mutated on a single construct. In these mutants, the target residues C466 and C467 are abolished by the −1 and +1 mutation respectively. In both +1 and −1 combined mutant constructs, the overall editing profile and extent of the transcripts were different from the wild type (Fig. 2). Notably, site C385 had a decreased editing efficiency in combined +1 mutant although it was not mutated (Fig. 2B). Comparing the editing efficiency of individual sites in transcripts from the combined mutant with those from single mutants, we observed that sites C167, C169, C449, C482, C550, C638 and C704 presented a similar response. In contrast, sites C30(−1), C620(+1) and C620(−1) showed weaker editing efficiency in transcripts from the single mutant construct than those from combined mutant ones (Table 1). For sites C587(+1) and C587(−1) the situation was the contrary as editing efficiency was higher in combined than individual mutants. Moreover, sites C563(+1) and C682(−1) reached 10% editing efficiency in individual mutants whereas they were not edited in combined constructions. These results indicate that some editing sites are not autonomous and that the editing reaction may be affected by mutations outside of the −16/+6 region. Indeed, the editing profile of cox2 transcripts from single −1 and +1 mutants (supplemental Fig. S1) indicate that modifications in point mutations may have an impact on the editing status of the mRNA.


The RNA editing pattern of cox2 mRNA is affected by point mutations in plant mitochondria.

Castandet B, Araya A - PLoS ONE (2011)

Editing status of cox2 transcripts carrying combined −1 or +1 mutations.Gray bars represent the editing efficiency on the wild type transcripts. (A) Editing status of mRNA from the combined −1 mutant (blue bars). (B) Editing status of mRNA from the combined +1 mutant (red bars). The sites C77, C259 and C385 not mutated in the −1 or +1 combined constructs are shown by light gray bars. The results presented are representative from at least two separate experiments. Editing efficiency variations in replicates was lower than 10%.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113845&req=5

pone-0020867-g002: Editing status of cox2 transcripts carrying combined −1 or +1 mutations.Gray bars represent the editing efficiency on the wild type transcripts. (A) Editing status of mRNA from the combined −1 mutant (blue bars). (B) Editing status of mRNA from the combined +1 mutant (red bars). The sites C77, C259 and C385 not mutated in the −1 or +1 combined constructs are shown by light gray bars. The results presented are representative from at least two separate experiments. Editing efficiency variations in replicates was lower than 10%.
Mentions: In a second set of experiments, either the −1 or the +1 neighbor residues from all editing sites, with the exception of C77, C259 and C385, were mutated on a single construct. In these mutants, the target residues C466 and C467 are abolished by the −1 and +1 mutation respectively. In both +1 and −1 combined mutant constructs, the overall editing profile and extent of the transcripts were different from the wild type (Fig. 2). Notably, site C385 had a decreased editing efficiency in combined +1 mutant although it was not mutated (Fig. 2B). Comparing the editing efficiency of individual sites in transcripts from the combined mutant with those from single mutants, we observed that sites C167, C169, C449, C482, C550, C638 and C704 presented a similar response. In contrast, sites C30(−1), C620(+1) and C620(−1) showed weaker editing efficiency in transcripts from the single mutant construct than those from combined mutant ones (Table 1). For sites C587(+1) and C587(−1) the situation was the contrary as editing efficiency was higher in combined than individual mutants. Moreover, sites C563(+1) and C682(−1) reached 10% editing efficiency in individual mutants whereas they were not edited in combined constructions. These results indicate that some editing sites are not autonomous and that the editing reaction may be affected by mutations outside of the −16/+6 region. Indeed, the editing profile of cox2 transcripts from single −1 and +1 mutants (supplemental Fig. S1) indicate that modifications in point mutations may have an impact on the editing status of the mRNA.

Bottom Line: It has been reported that a short region surrounding the target C forms the cis-recognition elements, but individual residues on it do not play similar roles for the different editing sites.We found that four different recognition patterns can be distinguished: (a) +1 dependency, (b) -1 dependency, (c) +1/-1 dependency, and (d) no dependency on nearest neighbor residues.Our data suggest that the complex response observed for cox2 mRNA may be a consequence of the fate of the transcript during mitochondrial gene expression.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, MCMP- UMR5234, Centre National de la Recherche Scientifique and Université Bordeaux Segalen. Bordeaux, France.

ABSTRACT
The mitochondrial transcriptome from land plants undergoes hundreds of specific C-to-U changes by RNA editing. These events are important since most of them occur in the coding region of mRNAs. One challenging question is to understand the mechanism of recognition of a selected C residue (editing sites) on the transcript. It has been reported that a short region surrounding the target C forms the cis-recognition elements, but individual residues on it do not play similar roles for the different editing sites. Here, we studied the role of the -1 and +1 nucleotide in wheat cox2 editing site recognition using an in organello approach. We found that four different recognition patterns can be distinguished: (a) +1 dependency, (b) -1 dependency, (c) +1/-1 dependency, and (d) no dependency on nearest neighbor residues. A striking observation was that whereas a 23 nt cis region is necessary for editing, some mutants affect the editing efficiency of unmodified distant sites. As a rule, mutations or pre-edited variants of the transcript have an impact on the complete set of editing targets. When some Cs were changed into Us, the remaining editing sites presented a higher efficiency of C-to-U conversion than in wild type mRNA. Our data suggest that the complex response observed for cox2 mRNA may be a consequence of the fate of the transcript during mitochondrial gene expression.

Show MeSH