Search results for "Protein kinase"
showing 10 items of 1188 documents
Bacterial rhamnolipids are novel MAMPs conferring resistance to Botrytis cinerea in grapevine
2009
International audience; Rhamnolipids produced by the bacteria Pseudomonas aeruginosa are known as very efficient biosurfactant molecules. They are used for a wide range of industrial applications, especially in food, cosmetics and pharmaceutical formulations as well as in bioremediation of pollutants. In this paper, the role of rhamnolipids as novel molecules triggering defence responses and protection against the fungus Botrytis cinerea in grapevine is presented. The effect of rhamnolipids was assessed in grapevine using cell suspension cultures and vitro-plantlets. Ca2+ influx, mitogen-activated protein kinase activation and reactive oxygen species production form part of early signalling…
Phosphoproteins Involved in the Signal Transduction of Cryptogein, an Elicitor of Defense Reactions in Tobacco
2000
We previously reported that the signal transduction of cryptogein, an elicitor of defense reactions in Nicotiana tabacum cells, involves upstream protein phosphorylation. In the present study, induction of these early physiological events was further investigated with inhibitors of protein phosphatase (PP), okadaïc acid, and calyculin A. Calyculin A mimicked the effects of cryptogein, inducing an influx of calcium, an extracellular alkalinization, and the production of active oxygen species (AOS), suggesting that during cryptogein signal transduction the balance between specific protein kinase (PK) and PP activities was modified. To identify the phosphorylated proteins that could be involv…
Protein phosphorylation is induced in tobacco cells by the elicitor cryptogein
1994
Changes in plasmalemma ion fluxes were observed when tobacco (Nicotiana tabacum) cells were treated with cryptogein, a proteinaceous elicitor from Phytophthora cryptogea. A strong alkalization of the culture medium, accompanied by a leakage of potassium, was induced within a few minutes of treatment. These effects reached a maximum after 30 to 40 min and lasted for several hours. This treatment also resulted in a rapid, but transient, production of activated oxygen species. All these physiological responses were fully sensitive to staurosporine, a known protein kinase inhibitor. Furthermore, a study of protein phosphorylation showed that cryptogein induced a staurosporine-sensitive phosphor…
Nuclear protein kinases: still enigmatic components in plant cell signalling
2010
International audience; Plants constantly face changing conditions in their environment. Unravelling the transduction mechanisms from signal perception at the plasma membrane level down to gene expression in the nucleus is a fascinating challenge. Protein phosphorylation, catalysed by protein kinases, is one of the major posttranslational modifications involved in the specificity, kinetic(s) and intensity of a signal transduction pathway. Although commonly assumed, the involvement of nuclear protein kinases in signal transduction is often poorly characterized. In particular, both their regulation and mode of action remain to be elucidated and may lead to the unveiling of new original mechan…
Nitric oxide signalling in plants: interplays with Ca2+ and protein kinase
2008
International audience; Much attention has been paid to nitric oxide (NO)research since its discovery as a physiological mediator of plant defence responses. In recent years, newer roles have been attributed to NO, ranging from root development to stomatal closure. The molecular mechanisms underlying NO action in plants are just begun to emerge. The currently available data illustrate that NO can directly influence the activity of target proteins through nitrosylation and has the capacity to act as a Ca2+-mobilizing intracellular messenger. The interplay between NO and Ca2+ has important functional implications, expanding and enriching the possibilities for modulating transduction processes…
Ergosterol elicits oxidative burst in tobacco cells via phospholipase A2 and protein kinase C signal pathway
2004
Ergosterol, a typical fungal sterol, induced in tobacco (Nicotiana tabacum L. cv. Xanthi) suspension cells the synthesis of reactive oxygen species and alkalization of the external medium that are dependent on the mobilization of calcium from internal stores. We used specific inhibitors to elucidate the signal pathway triggered by ergosterol compared with cryptogein, a proteinaceous elicitor of Phytophthora cryptogea. HerbimycinA and genistein, inhibitors of tyrosine protein kinases, had no effect on the oxidative burst and pH changes induced by bothelicitors.Similarly,H-89,aninhibitorofproteinkinaseA,hadnoeffectontheinductionofthesedefensereactions.However,theresponse to both elicitors was…
Cytosolic calcium rises and related events in ergosterol-treated Nicotiana cells
2011
International audience; The typical fungal membrane component ergosterol was previously shown to trigger defence responses and protect plants against pathogens. Most of the elicitors mobilize the second messenger calcium, to trigger plant defences. We checked the involvement of calcium in response to ergosterol using Nicotiana plumbaginifolia and Nicotiana tabacum cv Xanthi cells expressing apoaequorin in the cytosol. First, it was verified if ergosterol was efficient in these cells inducing modifications of proton fluxes and increased expression of defence-related genes. Then, it was shown that ergosterol induced a rapid and transient biphasic increase of free [Ca2þ]cyt which intensity dep…
Early signaling events induced by elicitors of plant defenses
2006
International audience; Plant pathogen attacks are perceived through pathogenissued compounds or plant-derived molecules that elicit defense reactions. Despite the large variety of elicitors, general schemes for cellular elicitor signaling leading to plant resistance can be drawn. In this article, we review early signaling events that happen after elicitor perception, including reversible protein phosphorylations, changes in the activities of plasma membrane proteins, variations in free calcium concentrations in cytosol and nucleus, and production of nitric oxide and active oxygen species. These events occur within the first minutes to a few hours after elicitor perception. One specific eli…
Echovirus 1 internalization negatively regulates epidermal growth factor receptor downregulation
2016
We have demonstrated previously that the human picornavirus Echovirus 1 (EV1) triggers an infectious internalization pathway that follows closely, but seems to stay separate, from the epidermal growth factor receptor (EGFR) pathway triggered by epidermal growth factor (EGF). Here, we confirmed by using live and confocal microscopy that EGFR and EV1 vesicles are following intimately each other but are distinct entities with different degradation kinetics. We show here that despite being sorted to different pathways and located in distinct endosomes, EV1 inhibits EGFR downregulation. Simultaneous treatment with EV1 and EGF led to an accumulation of EGFR in cytoplasmic endosomes, which was evi…
Cellular Concentrations of the Transporters DctA and DcuB and the Sensor DcuS of Escherichia coli and the Contributions of Free and Complexed DcuS to…
2017
ABSTRACT In Escherichia coli , the catabolism of C 4 -dicarboxylates is regulated by the DcuS-DcuR two-component system. The functional state of the sensor kinase DcuS is controlled by C 4 -dicarboxylates (like fumarate) and complexation with the C 4 -dicarboxylate transporters DctA and DcuB, respectively. Free DcuS (DcuS F ) is known to be constantly active even in the absence of fumarate, whereas the DcuB-DcuS and DctA-DcuS complexes require fumarate for activation. To elucidate the impact of the transporters on the functional state of DcuS and the concentrations of DcuS F and DcuB-DcuS (or DctA-DcuS), the absolute levels of DcuS, DcuB, and DctA were determined in aerobically or anaerobic…