Consummating Signal Transduction

Sehnke, Paul C.; DeLille, Justin M.; Ferl, Robert J.

doi:10.1105/tpc.010430

Cited by 167 publications

(50 citation statements)

References 106 publications

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“…Many enzymes in C metabolism, such as sucrose phosphate synthase, sucrose synthase, and 3-hydroxy-3-methylglutaryl CoA reductase (8,32,35), are also controlled by phosphorylation and the binding of 14-3-3. The targets of most of the plant 14-3-3 have not been identified, and many of the plant 14-3-3 are poorly characterized (36). Our results suggest that the 14-3-3s phosphorylated by SnRK2.8 may regulate C or N metabolism through interaction with unknown targets.…”

Section: Discussionmentioning

confidence: 85%

Phosphoproteomic identification of targets of the Arabidopsis sucrose nonfermenting-like kinase SnRK2.8 reveals a connection to metabolic processes

Shin

Alvarez

Burch

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

132

105

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SnRK2.8 is a member of the sucrose nonfermenting-related kinase family that is down-regulated when plants are deprived of nutrients and growth is reduced. When this kinase is over expressed in Arabidopsis, the plants grow larger. To understand how this kinase modulates growth, we identified some of the proteins that are phosphorylated by this kinase. A new phosphoproteomic method was used in which total protein from plants overexpressing the kinase was compared with total protein from plants in which the kinase was inactivated. Protein profiles were compared on two-dimensional gels following staining by a dye that recognizes phosphorylated amino acids. Candidate target proteins were confirmed with in vitro phosphorylation assays, using the kinase and target proteins that were purified from Escherichia coli. Seven target proteins were confirmed as being phosphorylated by SnRK2.8. Certain targets, such as 14-3-3 proteins, regulate as yet unidentified proteins, whereas other targets, such as glyoxalase I and ribose 5-phosphate isomerase, detoxify byproducts from glycolysis and catalyze one of the final steps in carbon fixation, respectively. Also, adenosine kinase and 60S ribosomal protein were confirmed as targets of SnRK2.8. Using mass spectrometry, we identified phosphorylated residues in the SnRK2.8, the 14-3-3 , and the 14-3-3 . These data show that the expression of SnRK2.8 is correlated with plant growth, which may in part be due to the phosphorylation of enzymes involved in metabolic processes.14-3-3 ͉ nutrient deprivation ͉ plant ͉ potassium T he mammalian AMPK (AMP-activated protein kinase), the yeast SNF (sucrose nonfermenting) 1 protein kinase, and the plant SnRK (SNF1-related protein kinase) are highly conserved and play broad roles in growth and metabolic responses to cellular stress (1). Mammalian cells sense glucose levels through the mammalian target of rapamycin kinase, which is part of an AMPK complex. AMPK is implicated in the development and treatment of metabolic disorders, including obesity and type 2 diabetes (2), and mutations in AMPK causes cardiac abnormalities (3). In yeast, SNF1 is required for regulation of glucose-responsive genes necessary for pseudohyphal growth in response to nutrient limitations (4) and for controlling the onset of meiosis in yeast (5). SNF1 provides a mechanism for crosstalk between metabolic pathways and cell cycle signaling processes (6). Mammal AMPK and yeast SNF1 act as energy-level sensors that function to regulate metabolism during low-energy conditions.

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Section: Discussionmentioning

confidence: 85%

Phosphoproteomic identification of targets of the Arabidopsis sucrose nonfermenting-like kinase SnRK2.8 reveals a connection to metabolic processes

Shin

Alvarez

Burch

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

132

105

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“…14-3-3 proteins are phosphopeptide-binding proteins that bind to two types of consensus sequences: RXXXpSXP and RXXpSXP (22). Phosphorylation of the serine residue is required for 14-3-3 binding (22).…”

Section: Suppressing Osbzr1 Expression By Rnai Leads To Br-insensitivementioning

confidence: 99%

“…Studies in metazoans have demonstrated important roles of 14-3-3 proteins as major regulators of primary metabolism and cellular signal transduction (21). In plants, 14-3-3 proteins have been shown to interact with large numbers of proteins, which include metabolic enzymes, signaling proteins, and transcription factors (22)(23)(24)(25). However, their specific role in a signal transduction pathway has yet to be illustrated.…”

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confidence: 99%

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Functions of OsBZR1 and 14-3-3 proteins in brassinosteroid signaling in rice

Bai

Zhang²,

Gampala³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

386

336

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Brassinosteroids (BR) are essential growth hormones found throughout the plant kingdom. BR bind to the receptor kinase BRI1 on the cell surface to activate a signal transduction pathway that regulates nuclear gene expression and plant growth. To understand the downstream BR signaling mechanism in rice, we studied the function of OsBZR1 using reverse genetic approaches and identified OsBZR1-interacting proteins. Suppressing OsBZR1 expression by RNAi resulted in dwarfism, erect leaves, reduced BR sensitivity, and altered BR-responsive gene expression in transgenic rice plants, demonstrating an essential role of OsBZR1 in BR responses in rice. Moreover, a yeast two-hybrid screen identified 14-3-3 proteins as OsBZR1-interacting proteins. Mutation of a putative 14-3-3-binding site of OsBZR1 abolished its interaction with the 14-3-3 proteins in yeast and in vivo. Such mutant OsBZR1 proteins suppressed the phenotypes of the Arabidopsis bri1-5 mutant and showed an increased nuclear distribution compared with the wild-type protein, suggesting that 14-3-3 proteins directly inhibit OsBZR1 function at least in part by reducing its nuclear localization. These results demonstrate a conserved function of OsBZR1 and an important role of 14-3-3 proteins in brassinosteroid signal transduction in rice.steroid ͉ nuclear localization ͉ GSK3 ͉ phosphorylation B rassinosteroids (BR) are polyhydroxylated steroid phytohormones with important roles in regulating a wide range of cellular and development processes, such as stem elongation, senescence, seed germination, reproductive development, and photomorphogenesis (1, 2). BR-deficient and BR-insensitive mutants have been identified in Arabidopsis thaliana (1), pea, tomato, barley, and rice (3). Although strong BR mutants show multiple growth defects, including dwarfism, male sterility, delayed senescence, and constitutive photomorphogenesis in the dark (1), weak BR mutants in rice and barley have increased grain yield because of erect leaves and reduced plant height (4-6). It is believed that manipulating BR level or sensitivity can improve plant productivity.Molecular genetic studies in A. thaliana have illustrated a BRsignaling pathway that includes two receptor kinases (BRI1 and BAK1) on the cell surface, a soluble glycogen synthase kinase 3-like kinase (BIN2), a phosphatase (BSU1), and two homologous transcription factors (BZR1 and BZR2/BES1) (1, 7). BR directly bind to the extracellular domain of BRI1 and activate its intracellular kinase activity (8). Activation of BRI1 leads to interaction with, and activation of, another receptor kinase, BAK1, which has been proposed to act as BRI1's coreceptor (9, 10). Downstream of the receptor kinases, the BIN2 kinase and BSU1 phosphatase regulate the phosphorylation status of BZR1 and BZR2/BES1 (11-14). BR activate BZR1 and BZR2/BES1 by inducing their dephosphorylation, possibly by inhibiting BIN2 or activating BSU1. Activated BZR1 and BES1 bind to promoters of BR target genes to regulate their expression (15, 16).BZR1 and BZR2/BES1 share 88...

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“…Since this interaction often results in changed activity of the target protein, 14-3-3 proteins have emerged as important regulators of enzyme function (1)(2)(3)(4)(5). Binding to a given target most often requires a phosphorylated binding motif (1,4,6,7), and signal transduction components such as protein kinases and protein phosphatases therefore become crucial for determining whether interaction between 14-3-3 protein and the target will occur in vivo (4,8). 14-3-3 proteins regulate the activity of several important plant enzymes.…”

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confidence: 99%

The Binding Site for Regulatory 14-3-3 Protein in Plant Plasma Membrane H+-ATPase

Fuglsang¹,

Borch

Bych³

et al. 2003

Journal of Biological Chemistry

100

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. We report binding of 14-3-3 protein to a nonphosphorylated peptide representing the 34 C-terminal residues of the Arabidopsis plasma membrane H ؉ -ATPase isoform 2 (AHA2). Following site-directed mutagenesis within the 45 C-terminal residues of AHA2, we conclude that, in addition to the 946 YpTV motif, a number of residues located further upstream are required for phosphorylation-independent binding of 14-3-3. Among these, Thr-924 is important for interaction with 14-3-3 protein even when Thr-947 is phosphorylated. We suggest that the role of phosphorylation, which is accentuated by fusicoccin, is to stabilize protein-protein interaction between 14-3-3 protein and several residues of the H ؉ -ATPase C-terminal domain.

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Consummating Signal Transduction

Cited by 167 publications

References 106 publications

Phosphoproteomic identification of targets of the Arabidopsis sucrose nonfermenting-like kinase SnRK2.8 reveals a connection to metabolic processes

Phosphoproteomic identification of targets of the Arabidopsis sucrose nonfermenting-like kinase SnRK2.8 reveals a connection to metabolic processes

Functions of OsBZR1 and 14-3-3 proteins in brassinosteroid signaling in rice

The Binding Site for Regulatory 14-3-3 Protein in Plant Plasma Membrane H+-ATPase

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