title: SD3, an Arabidopsis thaliana homolog of TIM21, affects intracellular ATP levels and seedling development.
abstract: It is poorly understood how plants control their growth by cell division, elongation, and differentiation. We have characterized a seedling-lethal mutant segregation distortion 3 (sd3) that showed a very dwarf phenotype when grown in the light and, in the dark, had short hypocotyls with reduced ploidy levels. The corresponding gene of SD3 encodes a protein with high similarity to yeast translocase on the inner mitochondrial membrane 21 (TIM21), which is a component of the TIM23 complex. Indeed, SD3 protein fused to GFP localized in the mitochondria. SD3 overexpression increased cotyledon size in the light and hypocotyl thickness in the dark. The expression of genes for several subunits of the respiratory-chain complexes III and IV was up-regulated in SD3-overexpressing plants. Furthermore, these plants showed high levels of ATP whereas those of sd3 were low. These results suggested that SD3 induced an increase in cell size by raising the expression of the respiratory-chain subunit genes and hence increased the intracellular ATP levels. We propose that intracellular ATP levels regulated by mitochondria control plant organ size.
authors: Plant Functional Genomics Research Group, Plant Science Center, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors: Hidefumi
authors: H
authors: Hamasaki
authors: Takeshi
authors: T
authors: Yoshizumi
authors: Naoki
authors: N
authors: Takahashi
authors: Mieko
authors: M
authors: Higuchi
authors: Takashi
authors: T
authors: Kuromori
authors: Yuko
authors: Y
authors: Imura
authors: Hiroaki
authors: H
authors: Shimada
authors: Minami
authors: M
authors: Matsui
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002452:Cell Count; D048429:Cell Size; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D018546:Hypocotyl / Q000254:growth & development / Q000528:radiation effects; D042541:Intracellular Space / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry*; D051336:Mitochondrial Membranes / Q000378:metabolism / Q000528:radiation effects; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011123:Polyploidy; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D036226:Seedlings / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; C573534:SD3 protein, Arabidopsis; D029701:Saccharomyces cerevisiae Proteins; C500397:Tim21 protein, S cerevisiae; D000255:Adenosine Triphosphate