The Carbonic Anhydrase Domain of Arabidopsis Respiratory Complex I is involved in Carbon Metabolism

SOTO, DÉBORA; CÓRDOBA, JUAN PABLO; MARTIN, MARÍA VICTORIA; BRAUN HANS-PETER; PAGNUSSAT, GABRIELA CAROLINA; ZABALETA, EDUARDO JULIÁN

Rosario

Congreso; 8º International Conference for Plant Mitochondrial Biology; 2013

Plant Mitochondrial Biology

The NADH-ubiquinone oxidoreductase (Complex I (CI), EC 1.6.5.3) of the mitochondrial respiratory chain is the principal entrance of electrons from metabolism and redox balance. Additionally, in a variety of eukaryotic organisms, except animal and fungi (Opisthokonta), it contains an extra domain composed of trimers of putative gamma carbonic anhydrases, named CA domain, proposed as an ancestral assembly factor. However, its physiological role in plants is not fully understood. In this report, we present evidences that this domain has acquired in plants a role in photosynthesis efficiency in the context of photorespiration. Arabidopsis mutant plants affected in two CA subunits show a weak photorespiratory phenotype. These mutants present growth retardation compared to wild type plants grown in normal air. However, this phenotype is rescued by cultivating plants in a high (2000 ppm) carbon dioxide atmosphere. Moreover, transcription of all five CA subunits is repressed in plants grown under non-photorespiratory conditions. Taken together, these results strongly suggest that the CA domain of plant complex I is required to sustain an efficient photosynthesis at normal-photorespiratory conditions.