title: The γ-carbonic anhydrase subcomplex of mitochondrial complex I is essential for development and important for photomorphogenesis of Arabidopsis.
abstract: Complex I (NADH:ubiquinone oxidoreductase) is the entry point for electrons into the respiratory electron transport chain; therefore, it plays a central role in cellular energy metabolism. Complex I from different organisms has a similar basic structure. However, an extra structural module, referred to as the γ-carbonic anhydrase (γCA) subcomplex, is found in the mitochondrial complex I of photoautotrophic eukaryotes, such as green alga and plants, but not in that of the heterotrophic eukaryotes, such as fungi and mammals. It has been proposed that the γCA subcomplex is required for the light-dependent life style of photoautotrophic eukaryotes, but this hypothesis has not been successfully tested. We report here a genetic study of the genes γCAL1 and γCAL2 that encode two subunits of the γCA subcomplex of mitochondrial complex I. We found that mutations of γCAL1 and γCAL2 in Arabidopsis (Arabidopsis thaliana) result in defective embryogenesis and nongerminating seeds, demonstrating the functional significance of the γCA subcomplex of mitochondrial complex I in plant development. Surprisingly, we also found that reduced expression of γCAL1 and γCAL2 genes altered photomorphogenic development. The γcal1 mutant plant expressing the RNA interference construct of the γCAL2 gene showed a partial constitutive photomorphogenic phenotype in young seedlings and a reduced photoperiodic sensitivity in adult plants. The involvement of the γCA subcomplex of mitochondrial complex I in plant photomorphogenesis and the possible evolutionary significance of this plant-specific mitochondrial protein complex are discussed.
authors.affiliation: College of Biological Sciences, Hunan University, Changsha 410082, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Rikard
authors.initials: R
authors.lastname: Fristedt
authors.forename: Xuhong
authors.initials: X
authors.lastname: Yu
authors.forename: Zugen
authors.initials: Z
authors.lastname: Chen
authors.forename: Hongtao
authors.initials: H
authors.lastname: Liu
authors.forename: Yurhee
authors.initials: Y
authors.lastname: Lee
authors.forename: Hongwei
authors.initials: H
authors.lastname: Guo
authors.forename: Sabeeha S
authors.initials: SS
authors.lastname: Merchant
authors.forename: Chentao
authors.initials: C
authors.lastname: Lin
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D005838:Genotype; D018525:Germination / Q000528:radiation effects; D008027:Light; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis / Q000528:radiation effects*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D017440:Photoperiod; D030821:Plants, Genetically Modified; D012639:Seeds / Q000254:growth & development / Q000528:radiation effects; D013045:Species Specificity
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; C579792:gammaCAL1 protein, Arabidopsis; C579793:gammaCAL2 protein, Arabidopsis; D002256:Carbonic Anhydrases; D042967:Electron Transport Complex I