Functional analyses of the small GTPases, AtRac/ROP, on the activation of ROS-producing enzymes, Atrboh, by heterologous coexpression

Abstract

Plant respiratory burst oxidase homolog (rboh) proteins have been implicated in the production of reactive oxygen species (ROS) both in stress responses and during development. Ten rboh genes (AtrbohA-J) have been identified in the genome of Arabidopsis. By applying a heterologous expression system using HEK293T cells, we recently showed that AtrbohC and D possess ROS-producing activity synergistically activated by binding of Ca²⁺ to the EF-hand region of the cytosolic domain and phosphorylation. (Ogasawara et al., JBC, 2008; Takeda et al., Science, 2008). Rboh proteins have recently been suggested to be regulated by cytosolic accessory factors including small GTPases (Wong et al., Plant Cell 2007; Oda et al., JBC 2009). We here established a heterologous co-expression system for functional characterization of possible regulators of Atrbohs. We will report effects of co-expression of AtRac/ROPs on the ROS-producing activity of Atrbohs and discuss their possible functions in the regulation of ROS production.