Screening for novel regulators of AtrbohD and AtrbohF, NADPH oxidases involved in production of reactive oxygen species

Abstract

Production of reactive oxygen species (ROS) by NADPH oxidases has been shown to play crucial roles in plant signaling such as regulation of biotic and abiotic defense responses, programmed cell death and root hair development. In contrast to the NADPH oxidase complex in mammalian phagocytes that consists of multiple regulatory subunits, only the homologs of the catalytic subunit NOX2 and the cytosolic small GTPase Rac have been found in plants. Plant NOX homologs are known as rboh (respiratory burst oxidase homolog). By applying a heterologous expression system with HEK293T cells, we recently showed that AtrbohC and AtrbohD possess ROS-producing enzyme activities synergistically activated by binding of Ca²⁺ and phosphorylation (Takeda et al., Science, 2008; Ogasawara et al., JBC, 2008). We screened for novel proteins that specifically interact with the N-terminal region of AtrbohD and AtrbohF using yeast two-hybrid assay. Characterization and possible functions of the candidates will be reported.