Phosphatidic acid binds to and inhibits the activity of Arabidopsis CTR1. J Exp Bot

Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, NL-1098 SM Amsterdam, The Netherlands.
Journal of Experimental Botany (Impact Factor: 5.53). 02/2007; 58(14):3905-14. DOI: 10.1093/jxb/erm243
Source: PubMed


Phosphatidic acid (PA) has only recently been identified as an important eukaryotic lipid-signalling molecule. In plants, PA formation is triggered by various biotic and abiotic stresses, including wounding, pathogen attack, drought, salinity, cold, and freezing. However, few molecular targets of PA have been identified so far. One of the best characterized is Raf-1, a mammalian MAPKKK. Arabidopsis thaliana CTR1 (constitutive triple response 1) is one of the plant homologues of Raf-1 and functions as a negative regulator of the ethylene signalling pathway. Here, it is shown that PA binds CTR1 and inhibits its kinase activity. Using different PA-binding assays, the kinase domain of CTR1 (CTR1-K) was found to bind PA directly. Addition of PA resulted in almost complete inhibition of CTR1 kinase activity and disrupted the intramolecular interaction between CTR1-K and the CTR1 N-terminal regulatory domain. Additionally, PA blocked the interaction of CTR1 with ETR1, one of the ethylene receptors. The basic amino acid motif shown to be required for PA binding in Raf-1 is conserved in CTR1-K. However, mutations in this motif did not affect either PA-binding or PA-dependent inhibition of CTR1 activity. Subsequent deletion analysis of CTR1's kinase domain revealed a novel PA-binding region at the C-terminus of the kinase.

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Available from: Teun Munnik, Jun 04, 2014
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    • "PA is also able to bind to CTR1 kinase in A. thaliana, resulting in inhibition of its activity. This process could contribute to the activation of ethylene signalling pathway in the absence of ethylene itself (Testerink et al., 2007). Although, provided that CTR1 is colocalised with ethylene receptor at the ER, an allocation of different pool of PA (comparing to plasma membrane PA) to this process should be considered. "
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    ABSTRACT: Despite the fact that all plants follow strict developmental programms, they also have intrinsic mechanisms to monitor the environment and activate appropriate responses at the (sub-)cellular level, facilitating adaptation to abiotic and biotic fluctuations. The functionality of plant adaptive systems always relies on the sum of signalling machineries that control their transition from the resting state. Phosphoglycerolipids play a role in such signalling mechanisms. These structural components of cell membranes can be converted into multiple bioactive lipids, but also into soluble molecules. Together they shape cell metabolism via binding to downstream protein targets, thus affecting enzymatic activi-ties, vesicle trafficking and ion fluxes. The conversion of lipids is catalysed by the hydrolytic activity of phospholipases and by the action of lipid-kinases and lipid-phosphatases. These activities are strictly regulated in plant cells and are highly reactive to various environmental signals. While phospholipases have been shown to be essential for plant growth and adaptability, many aspects of phosphoglyc-erolipid signalling at the molecular level remain unknown. Here, we summarise the latest concepts and challenges associated with phosphoglycerolipid signalling in relation to environmental responses in plants.
    Environmental and Experimental Botany 06/2015; 114. DOI:10.1016/j.envexpbot.2014.08.009 · 3.36 Impact Factor
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    • "PA is also recognized as signaling phospholipid [45]. PA is produced in response to xylanase treatments, and the accumulation of PA induces ROS production and cell death in tomato cells and Arabidopsis [50], [51], [52], [53]. Wound-induced PA accumulation causes JA accumulation in Arabidopsis plants [54]. "
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    ABSTRACT: We previously identified a gene related to the SEC14-gene phospholipid transfer protein superfamily that is induced in Nicotiana benthamiana (NbSEC14) in response to infection with Ralstonia solanacearum. We here report that NbSEC14 plays a role in plant immune responses via phospholipid-turnover. NbSEC14-silencing compromised expression of defense-related PR-4 and accumulation of jasmonic acid (JA) and its derivative JA-Ile. Transient expression of NbSEC14 induced PR-4 gene expression. Activities of diacylglycerol kinase, phospholipase C and D, and the synthesis of diacylglycerol and phosphatidic acid elicited by avirulent R. solanacearum were reduced in NbSEC14-silenced plants. Accumulation of signaling lipids and activation of diacylglycerol kinase and phospholipases were enhanced by transient expression of NbSEC14. These results suggest that the NbSEC14 protein plays a role at the interface between lipid signaling-metabolism and plant innate immune responses.
    PLoS ONE 05/2014; 9(5):e98150. DOI:10.1371/journal.pone.0098150 · 3.23 Impact Factor
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    • "Arabidopsis SnRK2.4 is rapidly and transiently activated in saline conditions and is targeted to punctate structures in epidermal and cortex cells in roots (McLoughlin et al., 2012). Activity of class 1 SnRK2 kinases is not directly regulated by PA (Testerink et al., 2007), therefore PA might spatially facilitate protein–protein interactions. Several proteins that interact or are regulated by class 1 SnRK2 kinases also bind to PA (Figure 1B). "
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    ABSTRACT: Adequate water supply is of utmost importance for growth and reproduction of plants. In order to cope with water deprivation, plants have to adapt their development and metabolism to ensure survival. To maximize water use efficiency, plants use a large array of signaling mediators such as hormones, protein kinases, and phosphatases, Ca(2) (+), reactive oxygen species, and low abundant phospholipids that together form complex signaling cascades. Phosphatidic acid (PA) is a signaling lipid that rapidly accumulates in response to a wide array of abiotic stress stimuli. PA formation provides the cell with spatial and transient information about the external environment by acting as a protein-docking site in cellular membranes. PA reportedly binds to a number of proteins that play a role during water limiting conditions, such as drought and salinity and has been shown to play an important role in maintaining root system architecture. Members of two osmotic stress-activated protein kinase families, sucrose non-fermenting 1-related protein kinase 2 and mitogen activated protein kinases were recently shown bind PA and are also involved in the maintenance of root system architecture and salinity stress tolerance. In addition, PA regulates several proteins involved in abscisic acid-signaling. PA-dependent recruitment of glyceraldehyde-3-phosphate dehydrogenase under water limiting conditions indicates a role in regulating metabolic processes. Finally, a recent study also shows the PA recruits the clathrin heavy chain and a potassium channel subunit, hinting toward additional roles in cellular trafficking and potassium homeostasis. Taken together, the rapidly increasing number of proteins reported to interact with PA implies a broad role for this versatile signaling phospholipid in mediating salt and water stress responses.
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