Browsing by Author "Araya, Alejandro"

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    A Nuclear Gene Encoding the Iron-Sulfur Subunit of Mitochondrial Complex II Is Regulated by B3 Domain Transcription Factors during Seed Development in Arabidopsis
    (AMER SOC PLANT BIOLOGISTS, 2009) Roschzttardtz, Hannetz; Fuentes, Ignacia; Vasquez, Marcos; Corvalan, Claudia; Leon, Gabriel; Gomez, Isabel; Araya, Alejandro; Holuigue, Loreto; Vicente Carbajosa, Jesus; Jordana, Xavier
    Mitochondrial complex II (succinate dehydrogenase) is part of the tricarboxylic acid cycle and the respiratory chain. Three nuclear genes encode its essential iron-sulfur subunit in Arabidopsis (Arabidopsis thaliana). One of them, SUCCINATE DEHYDROGENASE2-3 (SDH2-3), is specifically expressed in the embryo during seed maturation, suggesting that SDH2-3 may have a role as the complex II iron-sulfur subunit during embryo maturation and/or germination. Here, we present data demonstrating that three abscisic acid-responsive elements and one RY-like enhancer element, present in the SDH2-3 promoter, are involved in embryo-specific SDH2-3 transcriptional regulation. Furthermore, we show that ABSCISIC ACID INSENSITIVE3 (ABI3), FUSCA3 (FUS3), and LEAFY COTYLEDON2, three key B3 domain transcription factors involved in gene expression during seed maturation, control SDH2-3 expression. Whereas ABI3 and FUS3 interact with the RY element in the SDH2-3 promoter, the abscisic acid-responsive elements are shown to be a target for bZIP53, a member of the basic leucine zipper (bZIP) family of transcription factors. We show that group S1 bZIP53 protein binds the promoter as a heterodimer with group C bZIP10 or bZIP25. To the best of our knowledge, the SDH2-3 promoter is the first embryo-specific promoter characterized for a mitochondrial respiratory complex protein. Characterization of succinate dehydrogenase activity in embryos from two homozygous sdh2-3 mutant lines permits us to conclude that SDH2-3 is the major iron-sulfur subunit of mature embryo complex II. Finally, the absence of SDH2-3 in mutant seeds slows down their germination, pointing to a role of SDH2-3-containing complex II at an early step of germination.
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    RNA editing of apocytochrome b (cob) transcripts in mitochondria from two genera of plants
    (1993) Zanlungo Matsuhiro, Silvana; Bégu, Dominique; Quiñones, Verónica; Araya, Alejandro; Jordana De Buen, Xavier
    Editing of the complete coding region of cob transcripts from two genera of plants has been studied by cDNA sequence analysis. Eighteen and nine C residues are edited into U in the mitochondrial transcripts from wheat and potato respectively. Both systems share eight common editing sites; ten codons edited in wheat are "pre-edited" at the genomic level in potato, and one codon edited in potato is "pre-edited" in wheat. Most amino-acid modifications lead to hydrophobic residues and increase the homology between the COB polypeptides and the corresponding protein of other species. In two out of the nine potato cDNA clones, an additional C-to-T modification, which also leads to a change in the encoded amino acid, was identified. Heterogeneity observed at the carboxy-terminus of the COB open reading frame in Triticum aestivum and Triticum timopheevi is not corrected by editing.