Molecular Mechanisms for Ca²⁺-Induced Activation of Arabidopsis AtrbohD.

Abstract

Production of reactive oxygen species is induced during many physiological processes. Respiratory burst oxidase homolog (Rboh) genes have been identified in various plants as a major source for reactive oxygen species production. Rbohs possess transmembrane domains, N-terminal regulatory domain containing EF-hand like motifs, and C-terminal catalytic domain containing FAD-, NADPH-binding sites. We have been analyzing the molecular mechanisms for activation of AtrbohD by heterologous expression in HEK293T cells and physicochemical analyses of the regulatory domain. Activation of AtrbohD was mediated by binding of Ca²⁺ to its EF-hand region, and required the Ca²⁺-induced conformational change in the regulatory domain. We further analyzed possible involvement of Ca²⁺-induced dynamic intramolecular conformational change and interaction between the two cytosolic domains in the activation of AtrbohD.