title: Rice MPR25 encodes a pentatricopeptide repeat protein and is essential for RNA editing of nad5 transcripts in mitochondria.
abstract: 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.
authors: Laboratory of Environmental Plant Biotechnology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai 981-8555, Japan.
authors: Takushi
authors: T
authors: Toda
authors: Sota
authors: S
authors: Fujii
authors: Ko
authors: K
authors: Noguchi
authors: Tomohiko
authors: T
authors: Kazama
authors: Kinya
authors: K
authors: Toriyama
mesh_terms: D019943:Amino Acid Substitution; D019069:Cell Respiration; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D055786:Gene Knockout Techniques; D008027:Light; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009245:NADH Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010788:Photosynthesis; D035261:Plant Components, Aerial / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D021381:Protein Transport; D017393:RNA Editing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D017422:Sequence Analysis, DNA; D000099188:Alternative Oxidase
chemical_list: D024101:Mitochondrial Proteins; D009245:NADH Dehydrogenase; D010088:Oxidoreductases; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D000099188:Alternative Oxidase