RNA editing in wheat mitochondria proceeds by a deamination mechanism

Blanc, Valérie; Litvak, Simón; Araya, Alejandro

doi:10.1016/0014-5793(95)00991-h

Cited by 67 publications

(37 citation statements)

References 27 publications

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“…Moreover, the 3 H/ 32 P ratio was the same in UMP and CMP. indicating that deamination of cytidine into uridine plays a key role in RNA editing in plant mitochondria (Blanc et al, 1995). These results are in good agreement with the in organello experiments described previously which showed that the α-phosphate is retained during C-to-U conversion in plant mitochondrial RNAs (Rajasekhar et al, 1993).…”

Section: Mechanism Of Rna Editing In Plant Mitochondriasupporting

confidence: 92%

“…Unfortunately, they were not suitable to study the enzymatic mechanism involved in this reaction. Thus, we settled a simplified in vitro system for routine assays which uses an in vitro radioactively labelled atp9 mRNA as substrate (Blanc et al, 1995;Blanc et al, 1996). After incubation with the mitochondrial lysate the edited product was extensively digested with nuclease P1 and submitted to a double dimension thin-layer chromatography (TLC) to separate the 5' NMPs.…”

Section: Mechanism Of Rna Editing In Plant Mitochondriamentioning

confidence: 99%

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RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding

Araya¹

1998

Electron. J. Biotechnol.

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RNA editing in plant mitochondria is a post-transcriptional process involving the partial change of C residues into U. These C to U changes lead to the synthesis of proteins with an amino acid sequence different to that predicted from the gene. Proteins produced from edited mRNAs are more similar to those from organisms where this process is absent. This biochemical process involves cytidine deamination. The cytoplasmic male sterility (CMS) phenotype generated by the incompatibility between the nuclear and the mitochondrial genomes is an important agronomical trait which prevents inbreeding and favors hybrid production. The hypothesis that RNA editing leads to functional proteins has been proposed. This hypothesis was tested by constructing transgenic plants expressing a mitochondrial protein translated fom unedited mRNA. The transgenic "unedited" protein was addressed to the mitochondria leading to the appearance of mitochondrial dysfunction and generating the male sterile phenotype in transgenic tobacco plants. Male sterile plants were also obtained by expressing specifically a bacterial ribonuclease in the anthers. The economical benefits of artificially engineered male-sterile plants or carrying the (native) spontaneous CMS phenotype, implies the restoration to obtain fertile hybrids that will be used in agriculture. Restoration to fertility of transgenic plants was obtained either by crossing male-sterile plants carrying the "unedited" mRNA with plants carrying the same RNA, but in the antisense orientation or, in the case of plants expresing the ribonuclease, by crossing male-sterile plants with plants expressing an inhibitor specific of this enzyme. RNA editingGeneralities. The first time the word "RNA editing" was used, a dozen years ago, concerned the insertion or deletion of uridine residues in the mitochondrial RNAs of some trypanosomes. After that, RNA editing has been found in mitochondria and chloroplasts from land plants, in the mitochondria of some fungi, in the nuclear-cytoplasmic compartments from animal cells and in the genomes of some viruses. The RNA editing process involves in some cases the modification of residues in RNA or, in other cases, the insertion and/or deletion of nucleotides in messenger RNA (for some reviews see Adler and Hadjuk, 1994;Araya et al., 1994;Schuster and Brennicke, 1994;Scott, 1995;Smith et al., 1997;Stuart et al., 1997). The consequences of the RNA editing process are either the modification of the coded information for some amino acids or the generation of new initiation and/or termination codons. In organisms where RNA editing is active the protein sequence predicted from the gene may be different from that of the mRNA translated protein. While RNA editing is abondantly found in mitochondria and to a lesser extent in the chloroplast compartment of higher plants, it is not present in algae. RNA editing has also been descriibed in mitochondria from other organisms such as Physarum polycephalum, but not in yeast organelles. When detected in mammalian nuclear transcr...

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Section: Mechanism Of Rna Editing In Plant Mitochondriasupporting

confidence: 92%

Section: Mechanism Of Rna Editing In Plant Mitochondriamentioning

confidence: 99%

RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding

Araya¹

1998

Electron. J. Biotechnol.

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“…Initial in vitro experiments from plant mitochondria had indicated that the sugar phosphate backbone remains intact during the deamination step of C to U editing (6,(15)(16)(17). Analogous observations with the in vitro systems for tobacco and pea chloroplasts further support the similarity between the editing processes in both organelles (8,9).…”

mentioning

confidence: 61%

In Vitro RNA Editing in Pea Mitochondria Requires NTP or dNTP, Suggesting Involvement of an RNA Helicase

Takenaka

Brennicke

2003

Journal of Biological Chemistry

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To analyze the biochemical parameters of RNA editing in plant mitochondria and to eventually characterize the enzymes involved we developed a novel in vitro system. The high sensitivity of the mismatch-specific thymine glycosylase is exploited to facilitate reliable quantitative evaluation of the in vitro RNA editing products. A pea mitochondrial lysate correctly processes a C to U editing site in the cognate atp9 template. Reaction conditions were determined for a number of parameters, which allow first conclusions on the proteins involved. The apparent tolerance against specific Zn 2؉ chelators argues against the involvement of a cytidine deaminase enzyme, the theoretically most straightforward catalysator of the deamination reaction. Participation of a transaminase was investigated by testing potential amino group receptors, but none of these increased the RNA editing reaction. Most notable is the requirement of the RNA editing activity for NTPs. Any NTP or dNTP can substitute for ATP to the optimal concentration of 15 mM. This observation suggests the participation of an RNA helicase in the predicted RNA editing protein complex of plant mitochondria.RNA editing has been observed in various forms in diverse organisms including trypanosomes, mammals, slime molds, and land plants (1). In land plants, RNA editing has so far been reported in mitochondria and plastids. In flowering plants the majority of this organellar editing involves C to U conversions, with U to C changes occurring much more infrequently and only in mitochondria (2, 3, 4). In non-flowering plants this latter direction of RNA editing is much more common in mitochondria as well as in chloroplasts, the U to C reactions almost reaching the frequency of the C to U editing in the hornworts (5). Since its discovery more than a decade ago, progress into understanding how this process works has been hampered by the lack of manageable and reliable in vitro systems. The first in vitro system for plant mitochondrial RNA editing was successfully developed from wheat embryos (6), but has not been exploited further.Conclusions about the determinants of specificity during RNA editing in mitochondria and in plastids have initially been drawn from comparisons of transcribed sequence duplications (e.g. 7). Such comparisons suggested that upstream (5Ј) sequences are crucial in targeting the editing machinery and that downstream similarities are not sufficient to specify a site.These observations were corroborated by the recent breakthrough development of an in vitro editing system for plastids (8, 9) and an electroporation protocol for mitochondria (10,11). Mutational analysis of templates in these as well as in in vivo experiments in transgenic chloroplasts (12)(13)(14) showed that for several editing sites 20 -30 nucleotides upstream and 2-5 nucleotides downstream are sufficient to guide the editing activity, precisely what had initially been deduced for mitochondria (7).The biochemistry of this RNA editing activity is still largely unclear, and more detailed u...

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“…Data indicate that C-to-U edits occur by base modification rather than by base or nucleotide replacement (19)(20)(21), pointing to a cytidine deaminase as the responsible activity (the available evidence does not, however, exclude a transaminase activity, which could theoretically account for both C-to-U and U-to-C edits). Reproducible mitochondrial or chloroplast extracts capable of supporting efficient editing in vitro have proven very difficult to generate, so that analysis of the mechanism of C-to-U editing has to date been limited, with no biochemical investigation at all being reported in the case of U-to-C editing.…”

Section: Mechanism Of Plant Rna Editing: Catalytic Activity and Specimentioning

confidence: 95%

RNA editing in plant mitochondria: 20 years later

Gray

2009

IUBMB Life

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SummaryIn 1989, three laboratories (in Canada, France and Germany) independently and simultaneously reported the discovery of C-to-U RNA editing in plant mitochondria (1-3). To mark the 20th anniversary of this finding, the leaders of the three research teams have written personal essays describing the events leading up to the discovery in each of their laboratories. These essays are intended not only to capture historical facts but also to illustrate unexpected convergence in the process of scientific discovery, with different groups coming to the same conclusion, often very close together in time, drawing on different types of evidence and via sometimes quite different hypotheses and approaches. Essential background information pertaining to RNA editing in general and RNA editing in plant organelles in particular is provided in this overview.

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RNA editing in wheat mitochondria proceeds by a deamination mechanism

Cited by 67 publications

References 27 publications

RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding

RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding

In Vitro RNA Editing in Pea Mitochondria Requires NTP or dNTP, Suggesting Involvement of an RNA Helicase

RNA editing in plant mitochondria: 20 years later

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