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D Begu

Publications and source records attributed to D Begu.

3 recordsLinked to original sources
PubMed1995

RNA editing in wheat mitochondria.

C to U transitions in plant mitochondrial mRNA (RNA editing) lead to amino acid changes as well as to the creation of new initiation or termination codons. We established an in vitro system to assay and to dissect the process of wheat mitochondrial mRNA editing. A deamination mechanism explains most easily the observed C to U transitions. Several fractions of organellar protein participate in the editing machinery. Some of these proteins presumably carry the catalytic activity while others are typical RNA binding proteins and may confer specificity to the 'editosome' complex. To investigate the functional properties of protein products synthesized from unedited mRNAs, we constructed transgenic tobacco plants carrying an unedited gene coding for subunit 9 (ATP9) of the ATP synthase complex. The nuclear encoded 'unedited' protein product is targeted to the mitochondria with a heterologous presequence. A significant number of male sterile tobacco plants were obtained suggesting that at least the functional ATP9 protein requires RNA editing. This result suggests a novel approach to obtain artificial male sterile plants by using a physiological effect resulting in CMS which mimics the situation found in many natural populations.

Codon, Initiator↗
PubMed1992

An in vitro system for the editing of ATP synthase subunit 9 mRNA using wheat mitochondrial extracts.

A posttranscriptional modification (C-to-U) at specific positions of plant mitochondrial mRNA leads to changes in the amino acid sequence as well as to the emergence of novel initiation or termination sites. This phenomenon, named RNA editing, has been described for several mitochondrial genes from different plant sources. We have found recently that RNA editing of the ATP synthase subunit 9 (atp9) mRNA involves eight changes including the creation of a new stop codon. In this article, we describe an in vitro system devised to follow the editing of wheat mitochondrial atp9 mRNA. Nonedited mRNA was obtained to serve as substrate for this reaction by in vitro transcription of the corresponding gene with T7 RNA polymerase. The source of conversion factor(s) was a soluble fraction obtained from purified wheat mitochondria lysed with salt and detergent. Edited RNA molecules were detected by hybridization with an end-labeled synthetic oligodeoxynucleotide probe complementary to a short region containing four editing events. Optimal conditions for the in vitro RNA editing reaction were determined. The reaction is sensitive to high temperature and protease digestion. Pretreatment with micrococcal nuclease decreased RNA editing activity in the mitochondrial extract, suggesting that a nucleic acid is necessary for the enzymatic reactions. Analysis of the edited mRNA showed that the in vitro reaction led to the same products as those observed in vivo.

Amino Acid Sequence↗