Synergistic Activation of the Arabidopsis NADPH Oxidase AtrbohD by Ca2+ and Phosphorylation

摘要: Plant respiratory burst oxidase homolog (rboh) proteins, which are homologous to the mammalian 91-kDa glycoprotein subunit of phagocyte (gp91phox) or NADPH 2 (NOX2), have been implicated in production reactive oxygen species (ROS) both stress responses and during development. Unlike gp91phox/NOX2 protein, plant rboh proteins hydrophilic N-terminal regions containing two EF-hand motifs, suggesting that their activation is dependent on Ca2+. However, significance Ca2+ binding motifs ROS has unclear. By employing a heterologous expression system, we showed by Arabidopsis thaliana rbohD (AtrbohD) was induced ionomycin, ionophore induces influx into cell. This required conformational change region, as result motifs. We also AtrbohD directly phosphorylated vivo, this enhanced protein phosphatase inhibitor calyculin A (CA). Moreover, CA itself dramatically ionomycin-induced AtrbohD. Our results suggest phosphorylation synergistically activate ROS-producing enzyme activity