title: The CA domain of the respiratory complex I is required for normal embryogenesis in Arabidopsis thaliana.
abstract: The NADH-ubiquinone oxidoreductase [complex I (CI), EC 1.6.5.3] of the mitochondrial respiratory chain is the principal entry point of electrons, and vital in maintaining metabolism and the redox balance. In a variety of eukaryotic organisms, except animal and fungi (Opisthokonta), it contains an extra domain composed of putative gamma carbonic anhydrases subunits, named the CA domain, which was proposed to be essential for complex I assembly. There are two kinds of carbonic anhydrase subunits: CAs (of which there are three) and carbonic anhydrase-like proteins (CALs) (of which there are two). In plants, the CA domain has been linked to photorespiration. In this work, we report that Arabidopsis mutant plants affected in two specific CA subunits show a lethal phenotype. Double homozygous knockouts ca1ca2 embryos show a significant developmental delay compared to the non-homozygous embryos, which show a wild-type (WT) phenotype in the same silique. Mutant embryos show impaired mitochondrial membrane potential and mitochondrial reactive oxygen species (ROS) accumulation. The characteristic embryo greening does not take place and fewer but larger oil bodies are present. Although seeds look dark brown and wrinkled, they are able to germinate 12 d later than WT seeds. However, they die immediately, most likely due to oxidative stress.Since the CA domain is required for complex I biogenesis, it is predicted that in ca1ca2 mutants no complex I could be formed, triggering the lethal phenotype. The in vivo composition of a functional CA domain is proposed.
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Córdoba
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Marchetti
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015.
authors.forename: Débora
authors.initials: D
authors.lastname: Soto
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015.
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Martin
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015.
authors.forename: Gabriela Carolina
authors.initials: GC
authors.lastname: Pagnussat
authors.affiliation: Instituto de Investigaciones Biológicas IIB-CONICET-UNMdP, Funes 3250 3er nivel 7600 Mar del Plata, Argentina Received 6 October 2015; Revised 24 November 2015; Accepted 10 December 2015 ezabalet@mdp.edu.ar.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Zabaleta
mesh_terms: D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism*; D056130:Gametogenesis, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D020868:Gene Silencing; D017343:Genes, Plant; D006579:Heterozygote; D006720:Homozygote; D006861:Hydrogen Peroxide / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D000072417:Protein Domains; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000502:physiology; D057945:Self-Fertilization; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide; D042967:Electron Transport Complex I
keywords: Embryogenesis; gamma carbonic anhydrase; membrane potencial; reactive oxygen species; respiration; respiratory complex I.