title: AtNTRB is the major mitochondrial thioredoxin reductase in Arabidopsis thaliana.
abstract: NADPH-dependent thioredoxin reductases (NTR) are homodimeric enzymes that reduce thioredoxins. Two genes encoding NADPH-dependent thioredoxin reductases (AtNTRA and AtNTRB) were found in the genome of Arabidopsis thaliana. These originated from a recent duplication event and the encoded proteins are highly homologous. Previously, AtNTRA was shown to encode a dual targeted cytosol and mitochondrial protein. Here, we show that the AtNTRB gene encodes two mRNAs, presumably by initiating transcription at two different sites. The longer mRNA encodes a precursor polypeptide that is actively imported into mitochondria by a cleavage-associated mechanism, while the shorter mRNA encodes a cytosolic isoform. Isolation of Arabidopsis mutants with knocked-out AtNTRA or AtNTRB genes allowed us to prove that both genes encode cytosolic and mitochondrial isoforms. Interestingly, AtNTRB appeared to express the major mitochondrial NTR, while AtNTRA expresses as the major cytosolic isoform, suggesting that these two recently duplicated genes are evolving towards a specific function.
authors.affiliation: Laboratoire Génome et Développement des Plantes, Université de Perpignan, UMR CNRS 5096, 52 av. de Villeneuve, 66860 Perpignan, France. jpr@univ-perp.fr
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Reichheld
authors.forename: Etienne
authors.initials: E
authors.lastname: Meyer
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khafif
authors.forename: Géraldine
authors.initials: G
authors.lastname: Bonnard
authors.forename: Yves
authors.initials: Y
authors.lastname: Meyer
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002874:Chromosome Mapping; D003600:Cytosol / Q000737:chemistry / Q000201:enzymology; D020440:Gene Duplication; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology* / Q000502:physiology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D021381:Protein Transport; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D016415:Sequence Alignment; D013880:Thioredoxin-Disulfide Reductase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; C497521:NTRA protein, Arabidopsis; C497522:NTRB protein, Arabidopsis; D013880:Thioredoxin-Disulfide Reductase