New Insights into the physiological role of the Carbonic Anhydrase domain of Arabidopsis Respiratory Complex I

DEBORA SOTO, JUAN PABLO CORDOBA, VICTORIA MARTIN, GABRIELA PAGNUSSAT, EDUARDO ZABALETA

Mar del Plata

Congreso; XV Congreso Latinoamericano XXX Reunión Argentina de Fisiología Vegetal; 2014

Sociedad Argentina de Fisiología Vegetal

In Arabidopsis thaliana there are five gamma-type carbonic anhydrases proteins (ɣCAs), called CA1, CA2, CA3, CAL1 and CAL2. These proteins are encoded by nuclear genes and form an extra spherical domain (CA domain) in the membrane arm of mitochondrial complex I. The physiological role of this domain is currently unknown. None of the T-DNA insertional single mutants show any visible phenotype under normal conditions. An 80% reduction in complex I levels and a 50% lower oxygen consumption was observed only in the ca2 single mutant, but this does not result in an altered phenotype. In order to investigate the physiological role of the CA domain of Arabidopsis complex I, we performed crosses of single mutants to obtain different double mutants affected in ca2 and some other subunit of this domain. The phenotype of these mutants were analyzed under different CO2 atmospheres and physiological parameters such as oxygen consumption, carbon dioxide fixation and mitochondrial proteomic analyses were compared with those of single mutants and wild type plants. The double mutants ca2cal1, ca2cal2 y ca2ca3 showed a weak photorespiratory phenotype, while the double mutant ca2ca1 presented an embryo lethal phenotype.