Rice MPR25 encodes a pentatricopeptide repeat protein and is essential for RNA editing of nad5 transcripts in mitochondria

• Published in: The Plant journal : for cell and molecular biology 2012-11, Vol.72 (3), p.450-460
• Main Authors: Toda, Takushi, Fujii, Sota, Noguchi, Ko, Kazama, Tomohiko, Toriyama, Kinya
• Format: Article
• Language: English
• Subjects: alternative oxidase; Amino Acid Substitution; Amino acids; Biological and medical sciences; Cell Respiration; Chlorophyll; Chloroplasts; Chloroplasts - genetics; Chloroplasts - metabolism; Developmental stages; Electron transport; electron transport chain; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - genetics; Gene Knockout Techniques; genes; Genetic recombination; Growth rate; growth retardation; Leaves; Leucine; Light; Light effects; Mitochondria; Mitochondria - genetics; Mitochondria - metabolism; Mitochondrial DNA; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Mutagenesis, Insertional; mutants; NAD (coenzyme); nad5; NADH dehydrogenase; NADH Dehydrogenase - genetics; NADH Dehydrogenase - metabolism; Nucleotide sequence; Nucleotides; Organelles; Oryza - enzymology; Oryza - genetics; Oryza - growth & development; Oryza - radiation effects; Oryza sativa; Oryza sativa L; Oxidoreductases - genetics; Oxidoreductases - metabolism; pentatricopeptide repeat; Peptides; Phenotype; Photosynthesis; Plant biology; Plant Components, Aerial - enzymology; Plant Components, Aerial - genetics; Plant Components, Aerial - growth & development; Plant Components, Aerial - radiation effects; plant development; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - enzymology; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - radiation effects; Protein Transport; Proteins; Recombinant Fusion Proteins; Respiration; rice; RNA Editing; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Seedlings - enzymology; Seedlings - genetics; Seedlings - growth & development; Seedlings - radiation effects; Sequence Analysis, DNA; Serine
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313x.2012.05091.x

Pentatricopeptide repeat (PPR) proteins are involved in the modification of organelle transcripts. In this study, we investigated the molecular function in rice of the mitochondrial PPR‐encoding gene MITOCHONDRIAL PPR25 (MPR25), which belongs to the E subgroup of the PPR family. A Tos17 knockout mutant of MPR25 exhibited growth retardation and pale‐green leaves with reduced chlorophyll content during the early stages of plant development. The photosynthetic rate in the mpr25 mutant was significantly decreased, especially under strong light conditions, although the respiration rate did not differ from that of wild‐type plants. MPR25 was preferentially expressed in leaves. FLAG‐tagged MPR25 accumulated in mitochondria but not in chloroplasts. Direct sequencing revealed that the mpr25 mutant fails to edit a C–U RNA editing site at nucleotide 1580 of nad5, which encodes a subunit of complex I (NADH dehydrogenase) of the respiratory chain in mitochondria. RNA editing of this site is responsible for a change in amino acid from serine to leucine. Recombinant MPR25 directly interacted with the proximal region of the editing site of nad5 transcripts. However, the NADH dehydrogenase activity of complex I was not affected in the mutant. By contrast, genes encoding alternative NADH dehydrogenases and alternative oxidase were up‐regulated. The mpr25 mutant may therefore provide new information on the coordinated interaction between mitochondria and chloroplasts.