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Author Wong HL,Pinontoan R,Hayashi K,Tabata R,Yaeno T,Hasegawa K,Kojima C,Yoshioka H,Iba K,Kawasaki T,Shimamoto K
Title Regulation of rice NADPH oxidase by binding of Rac GTPase to its N-terminal extension.
Abstract:
Reactive oxygen species (ROS) produced by NADPH oxidase play critical roles in various cellular activities, including plant innate immunity response. In contrast with the large multiprotein NADPH oxidase complex of phagocytes, in plants, only the homologs of the catalytic subunit gp91phox and the cytosolic regulator small GTPase Rac are found. Plant homologs of the gp91phox subunit are known as Rboh (for respiratory burst oxidase homolog). Although numerous Rboh have been isolated in plants, the regulation of enzymatic activity remains unknown. All rboh genes identified to date possess a conserved N-terminal extension that contains two Ca2+ binding EF-hand motifs. Previously, we ascertained that a small GTPase Rac (Os Rac1) enhanced pathogen-associated molecular pattern-induced ROS production and resistance to pathogens in rice (Oryza sativa). In this study, using yeast two-hybrid assay, we found that interaction between Rac GTPases and the N-terminal extension is ubiquitous and that a substantial part of the N-terminal region of Rboh, including the two EF-hand motifs, is required for the interaction. The direct Rac-Rboh interaction was supported by further studies using in vitro pull-down assay, a nuclear magnetic resonance titration experiment, and in vivo fluorescence resonance energy transfer (FRET) microscopy. The FRET analysis also suggests that cytosolic Ca2+ concentration may regulate Rac-Rboh interaction in a dynamic manner. Furthermore, transient coexpression of Os Rac1 and rbohB enhanced ROS production in Nicotiana benthamiana, suggesting that direct Rac-Rboh interaction may activate NADPH oxidase activity in plants. Taken together, the results suggest that cytosolic Ca2+ concentration may modulate NADPH oxidase activity by regulating the interaction between Rac GTPase and Rboh.
Journal Plant Cell
Country Japan
Volume 19
Pages 4022-34
Year 2007
PubMed ID 18156215
PubMed Central ID -
DOI 10.1105/tpc.107.055624
URL -
Relation
Gene RAC1 RAC2 RAC3 RAC4 RAC5 RAC6 RAC7 RBOHA RBOHB RBOHC RBOHD RBOHE RBOHF RBOHG RBOHH RBOHI
INSD -
Strain Wild Core Collection -
Induced Mutation Lines(NIG Collection) -
Sterile Seed Strain -
Lethal Embryo
Mutantion Strain
-
Stages in Each Organ
- Muant Lines (Gene)
-
Cultivated Varieties(NIG Collection) -
Stages in Each Organ -
/rice/oryzabase