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Regulation of rice NADPH oxidase by binding of Rac GTPase to its N-terminal extension.
- Source :
-
The Plant cell [Plant Cell] 2007 Dec; Vol. 19 (12), pp. 4022-34. Date of Electronic Publication: 2007 Dec 21. - Publication Year :
- 2007
-
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.
- Subjects :
- Amino Acid Motifs
Calcium metabolism
Calcium physiology
Fluorescence Resonance Energy Transfer
Magnetic Resonance Spectroscopy
Microscopy, Confocal
Models, Genetic
Molecular Sequence Data
Mutation
NADPH Oxidases genetics
Oryza genetics
Plants, Genetically Modified
Protein Binding
Protoplasts metabolism
Reactive Oxygen Species metabolism
Nicotiana genetics
Nicotiana metabolism
Two-Hybrid System Techniques
rac GTP-Binding Proteins genetics
NADPH Oxidases metabolism
Oryza metabolism
rac GTP-Binding Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1040-4651
- Volume :
- 19
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- The Plant cell
- Publication Type :
- Academic Journal
- Accession number :
- 18156215
- Full Text :
- https://doi.org/10.1105/tpc.107.055624