Arabidopsis mTERF15 is required for mitochondrial nad2 intron 3 splicing and functional complex I activity.
Mitochondria play a pivotal role in most eukaryotic cells, as they are responsible for the generation of energy and diverse metabolic intermediates for many cellular events. During endosymbiosis, approximately 99% of the genes encoded by the mitochondrial genome were transferred into the host nucleus, and mitochondria import more than 1000 nuclear-encoded proteins from the cytosol to maintain structural integrity and fundamental functions, including DNA replication, mRNA transcription and RNA metabolism of dozens of mitochondrial genes. In metazoans, a family of nuclear-encoded proteins called the mitochondrial transcription termination factors (mTERFs) regulates mitochondrial transcription, including transcriptional termination and initiation, via their DNA-binding activities, and the dysfunction of individual mTERF members causes severe developmental defects. Arabidopsis thaliana and Oryza sativa contain 35 and 48 mTERFs, respectively, but the biological functions of only a few of these proteins have been explored. Here, we investigated the biological role and molecular mechanism of Arabidopsis mTERF15 in plant organelle metabolism using molecular genetics, cytological and biochemical approaches. The null homozygous T-DNA mutant of mTERF15, mterf15, was found to result in substantial retardation of both vegetative and reproductive development, which was fully complemented by the wild-type genomic sequence. Surprisingly, mitochondria-localized mTERF15 lacks obvious DNA-binding activity but processes mitochondrial nad2 intron 3 splicing through its RNA-binding ability. Impairment of this splicing event not only disrupted mitochondrial structure but also abolished the activity of mitochondrial respiratory chain complex I. These effects are in agreement with the severe phenotype of the mterf15 homozygous mutant. Our study suggests that Arabidopsis mTERF15 functions as a splicing factor for nad2 intron 3 splicing in mitochondria, which is essential for normal plant growth and development.
Institute of Plant Biology, National Taiwan University, Taipei, 116, Taiwan, ROC; Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC.
Ya-Wen
YW
Hsu
Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC.
Huei-Jing
HJ
Wang
Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC.
Ming-Hsiun
MH
Hsieh
Institute of Plant Biology, National Taiwan University, Taipei, 116, Taiwan, ROC.
Hsu-Liang
HL
Hsieh
Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC; Biotechnology Center, National Chung-Hsing University, Taichung, 402, Taiwan, ROC.
Guang-Yuh
GY
Jauh
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000378:metabolism*; D007438:Introns; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D063269:Mitochondrial Turnover / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D021381:Protein Transport; D012326:RNA Splicing
D029681:Arabidopsis Proteins; D042967:Electron Transport Complex I