A tomato tocopherol-binding protein sheds light on intracellular a-tocopherol metabolism in plants

Tocopherols are non-polar compounds synthesized in the plastids, which function as major antioxidants of the plant cells and are essential in the human diet. Both the intermediates and final products of the tocopherol biosynthetic pathway must cross plastid membranes to reach their sites of action. So far, no protein with tocopherol binding activity has been reported in plants. Here, we demonstrated that the tomato SlTBP protein is targeted to chloroplasts and able to bind α-tocopherol. SlTBP-knockdown tomato plants exhibited reduced levels of tocopherol in both leaves and fruits. Several tocopherol deficiency phenotypes were apparent in the transgenic lines, such as alterations in photosynthetic parameters, dramatic distortion of thylakoid membranes and significant variations in the lipid profile. These results, along with the altered expression of genes related to photosynthesis, and tetrapyrrole, lipid, isoprenoid, inositol/phosphoinositide and redox metabolism, suggest that SlTBP may act in conducting tocopherol (or its biosynthetic intermediates) between the plastid compartments and/or at the interface between chloroplast and endoplasmic reticulum membranes, affecting interorganellar lipid metabolism.Instituto de BiotecnologíaFil: Bermudez Salazar, Luisa. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lira, Bruno Silvestre. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; BrasilFil: Godoy, Fabiana de. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; BrasilFil: Boos, Irene. Technical University of Denmark. Center for Nanomedicine and Theranostics. Department of Chemistry; DinamarcaFil: Romano, Cecilia. Technical University of Denmark. Center for Nanomedicine and Theranostics. Department of Chemistry; DinamarcaFil: Previtali, Viola. Technical University of Denmark. Center for Nanomedicine and Theranostics. Department of Chemistry; DinamarcaFil: Almeida, Juliana. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; BrasilFil: Brehelin, Claire. Centre National de la Recherche Scientifique. Laboratory of Membrane Biogenesis; FranciaFil: Asis, Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; ArgentinaFil: Quadrana, Leandro Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; ArgentinaFil: Demarco, Diego. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; BrasilFil: Alseekh, Saleh. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Salinas Gamboa, Rigel. Universidad Autónoma Metropolitana. Laboratorio de Fisiología, Bioquímica y Biología Molecular de Plantas. Departamento de Ciencias de la Salud; MéxicoFil: Perez-Flores, Laura. Universidad Autónoma Metropolitana. Laboratorio de Fisiología, Bioquímica y Biología Molecular de Plantas. Departamento de Ciencias de la Salud; MéxicoFil: Dominguez, Pia Guadalupe. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rothan, Christophe. Institut National de la Recherche Agronomique. Fruit Biology and Pathology Unit; FranciaFil: Fernie, Alisdair R. Max Planck Institute of Molecular Plant Physiology; AlemaniaFil: Gonzalez, Maurıcio. Universidad de Chile. Laboratorio de Genética Molecular Vegetal; ChileFil: Stocker, Achim. University of Berne. Department of Chemistry and Biochemistry; SuizaFil: Hemmerle, Andreas. University of Berne. Department of Chemistry and Biochemistry; SuizaFil: Clausen, Mads Hartving. Technical University of Denmark. Center for Nanomedicine and Theranostics. Department of Chemistry; DinamarcaFil: Carrari, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; BrasilFil: Rossi, Magdalena. Universidade de São Pablo. Departamento de Botânica. Instituto de Biociencias; Brasi