The Carbonic Anhydrase Domian of respiratory Complex I is linked to photorespiration in Arabidopsis

DEBORA SOTO, JUAN PABLO CORDOBA, GABRIELA PAGNUSSAT, EDUARDO ZABALETA; BRAUN HANS-PETER; BARTOLI CARLOS; SCHMITZ JESSICA, MAURINO VERÓNICA

Rosario

Congreso; L Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The NADH-ubiquinone oxidoreductase (Complex I) of the mitochondrial respiratory chain has in a variety of eukaryotic organisms, except animal and fungi (Opisthokonta), an extra domain composed of trimers of putative gamma carbonic anhydrases, named Carbonic Anhydrase (CA) domain. Its physiological role in plants is not fully understood. Here, we present evidences that in plants this domain has acquired a role in photorespiration, thus regulating photosynthesis efficiency and plant biomass. Arabidopsis thaliana mutant plants affected in two CA subunits show a weak photorespiratory phenotype. These mutants grown in normal air present growth retardation compared to wild type plants. However, this phenotype is rescued by cultivating plants in a high (2000 ppm) carbon dioxide atmosphere. Moreover, under photorespiratory conditions, carbon assimilation is reduced and glycine accumulates, which suggests a photorespiratory disbalance. Furthermore, transcription of all five CA subunits is repressed in plants grown under non-photorespiratory conditions. These results strongly suggest that the CA domain of plant complex I contributes to sustain an efficient photosynthesis at ambient (photorespiratory) conditions.