Brassinosteroids Regulate Dissociation of BKI1, a Negative Regulator of BRI1 Signaling, from the Plasma Membrane

Wang, Xuelu; Chory, Joanne

doi:10.1126/science.1127593

Cited by 475 publications

(484 citation statements)

References 27 publications

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“…A number of other cytoplasmic kinases, including CPK3 CALCIUM-DEPENDENT PROTEIN KINASE6 (CDPK6), were also detected. Notably absent were the PP2AA1/RCN1 phosphatase (Wu et al, 2011) and the inhibitor protein BKI1 (Wang and Chory, 2006). Taken together, our results show that proteins that coimmunoprecipitate with BRL3 under our conditions include known components of the BR signaling pathway, but lack the main receptor BRI1.…”

Section: Identification Of Proteins That Coimmunoprecipitate With Brl3supporting

confidence: 60%

The BRASSINOSTEROID INSENSITIVE1–LIKE3 Signalosome Complex Regulates Arabidopsis Root Development

Fàbregas

Boeren

et al. 2013

The Plant Cell

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Brassinosteroid (BR) hormones are primarily perceived at the cell surface by the leucine-rich repeat receptor-like kinase BRASSINOSTEROID INSENSITIVE1 (BRI1). In Arabidopsis thaliana, BRI1 has two close homologs, BRI1-LIKE1 (BRL1) and BRL3, respectively, which are expressed in the vascular tissues and regulate shoot vascular development. Here, we identify novel components of the BRL3 receptor complex in planta by immunoprecipitation and mass spectrometry analysis. Whereas BRI1 ASSOCIATED KINASE1 (BAK1) and several other known BRI1 interactors coimmunoprecipitated with BRL3, no evidence was found of a direct interaction between BRI1 and BRL3. In addition, we confirmed that BAK1 interacts with the BRL1 receptor by coimmunoprecipitation and fluorescence microscopy analysis. Importantly, genetic analysis of brl1 brl3 bak1-3 triple mutants revealed that BAK1, BRL1, and BRL3 signaling modulate root growth and development by contributing to the cellular activities of provascular and quiescent center cells. This provides functional relevance to the observed protein-protein interactions of the BRL3 signalosome. Overall, our study demonstrates that cell-specific BR receptor complexes can be assembled to perform different cellular activities during plant root growth, while highlighting that immunoprecipitation of leucine-rich repeat receptor kinases in plants is a powerful approach for unveiling signaling mechanisms with cellular resolution in plant development.

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Section: Identification Of Proteins That Coimmunoprecipitate With Brl3supporting

confidence: 60%

The BRASSINOSTEROID INSENSITIVE1–LIKE3 Signalosome Complex Regulates Arabidopsis Root Development

Fàbregas

Boeren

et al. 2013

The Plant Cell

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“…2A). We used the transgenic line BKI1:YELLOW FLUO-RESCENT PROTEIN (YFP), which expresses the early BR signaling marker BRASSINOSTEROID KINASE INHIBITOR1 (BKI1; Wang and Chory, 2006), to test whether 9-LOX compounds trigger BR signaling. BKI1 is an inhibitory protein that dissociates from the BR receptor after BR activation and relocalizes from the plasma membrane to the cytosol.…”

Section: The 9-lox Oxylipins Activate the Br Pathwaymentioning

confidence: 99%

9-Lipoxygenase-derived oxylipins activate brassinosteroid signaling to promote cell wall-based defense and limit pathogen infection

et al. 2015

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The oxylipins, a large family of oxygenated lipid derivatives, regulate plant development and immunity. Two members of the 9-lipoxygenase (9-LOX) oxylipin pathway, 9-hydroxyoctadecatrienoic acid and 9-ketooctadecatrienoic acid, control root development and plant defense. Studies in Arabidopsis (Arabidopsis thaliana) using a series of 9-hydroxyoctadecatrienoic acidand 9-ketooctadecatrienoic acid-insensitive nonresponding to oxylipins (noxy) mutants showed the importance of the cell wall as a 9-LOX-induced defense component and the participation of NOXY proteins in signaling cell wall damage. Here, we examined 9-LOX signaling using the mutants lox1lox5, which lacks 9-LOX activity, and noxy2-2, which shows oxylipin insensitivity and mitochondrial dysfunction. Mutants in brassinosteroids (BRs), a class of plant hormones necessary for normal plant growth and the control of cell wall integrity, were also analyzed. Several lines of evidence indicated that 9-LOX-derived oxylipins induce BR synthesis and signaling to activate cell wall-based responses such as callose deposition and that constitutive activation of BR signaling in bri1-EMS-suppressor 1-D (bes1-D) plants enhances this response. We found that constitutive BR signaling in bes1-D and brassinolide-resistant 1-1D (bzr1-1D) mutants conferred resistance to Pseudomonas syringae. bes1-D and bzr1-1D showed increased resistance to Golovinomyces cichoracearum, an obligate biotrophic fungus that penetrates the cell wall for successful infection, whereas susceptibility was enhanced in lox1lox5 and noxy2-2. Our results indicate a sequential action of 9-LOX and BR signaling in activating cell wall-based defense, and this response prevents pathogen infection. These results show interaction between the 9-LOX and BR pathways and help to clarify their role in modulating plant defense.

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“…The membranelocalized proteins BSKs interact with BRI1 in vivo and activate the downstream signaling of BRI1 [16]. On the opposite, another BRI1-interacting protein, BKI1, negatively regulates BR signaling by limiting the association of BRI1 and BAK1 [17]. BIN2 is a GSK3-like protein and negatively controls BR signaling by phosphorylating two nuclear components BES1 and BZR1 [18,19].…”

Section: Introductionmentioning

confidence: 99%

Membrane steroid-binding protein 1 (MSBP1) negatively regulates brassinosteroid signaling by enhancing the endocytosis of BAK1

et al. 2009

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Brassinosteroids (BRs) are perceived by transmembrane receptors and play vital roles in plant growth and development, as well as cell in responses to environmental stimuli. The transmembrane receptor BRI1 can directly bind to brassinolide (BL), and BAK1 interacts with BRI1 to enhance the BRI1-mediated BR signaling. Our previous studies indicated that a membrane steroid-binding protein 1 (MSBP1) could bind to BL in vitro and is negatively involved in BR signaling. To further elucidate the underlying mechanism, we here show that MSBP1 specifically interacts with the extracellular domain of BAK1 in vivo in a BL-independent manner. Suppressed cell expansion and BR responses by increased expression of MSBP1 can be recovered by overexpressing BAK1 or its intracellular kinase domain, suggesting that MSBP1 may suppress BR signaling through interacting with BAK1. Subcellular localization studies revealed that both MSBP1 and BAK1 are localized to plasma membrane and endocytic vesicles and MSBP1 accelerates BAK1 endocytosis, which results in suppressed BR signaling by shifting the equilibrium of BAK1 toward endosomes. Indeed, enhanced MSBP1 expression reduces the interaction between BRI1 and BAK1 in vivo, demonstrating that MSBP1 acts as a negative factor at an early step of the BR signaling pathway.

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Brassinosteroids Regulate Dissociation of BKI1, a Negative Regulator of BRI1 Signaling, from the Plasma Membrane

Cited by 475 publications

References 27 publications

The BRASSINOSTEROID INSENSITIVE1–LIKE3 Signalosome Complex Regulates Arabidopsis Root Development

The BRASSINOSTEROID INSENSITIVE1–LIKE3 Signalosome Complex Regulates Arabidopsis Root Development

9-Lipoxygenase-derived oxylipins activate brassinosteroid signaling to promote cell wall-based defense and limit pathogen infection

Membrane steroid-binding protein 1 (MSBP1) negatively regulates brassinosteroid signaling by enhancing the endocytosis of BAK1

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