Composition of the integrated CA domain of mitochondrial complex I is different in embryos and leaves

CORDOBA JUAN PABLO; FASSOLARI S; PAGNUSSAT G; EDUARDO JULIAN ZABALETA

Rosario

Simposio; Simposio de Genómica Funcional de Plantas; 2017

SGFP

Mitochondrial complex I is the main entrance of electrons in electron transport chain. In plants and heterokonts, complex I contains an extra domain called Carbonic Anhydrase (CA) domain. This domain is supposed to be composed of trimmers of gamma type CA and CA-like subunits. In Arabidopsis thaliana, the gene family contains five members (CA1, CA2, CA3, CAL1, and CAL2). The CA domain is thought to be crucial for complex I assembly and thus essential for normal embryogenesis. It was also proposed to be important in the context of photorespiration. However, five proteins arranged in trimmers give the possibility of different composition of trimmers with specialized functions. The exact composition of trimmers and their putative physiological function are still under discussion. It was proposed the existence of CA1 and CA2 dependent complex I accounting for the 100% of complex I. In this model, CA3 is proposed to be outside the CA domain. In this work, we present evidence of the localization of CA3 and that the proportion of CA1 and CA2 dependent complex I changes in a tissue specific manner. In immature embryos, we found a high proportion of CA1 dependent complex I while in mature embryos, leaves or cell derived from leaves, CA2 dependent complex I is the more abundant. This difference might account for specific physiological functions.