Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of fusicoccin on the plasmalemma H+-ATPase has been investigated in a membrane fraction from 24 h old radish seedlings, in which Mg:ATP-dependent H+-transport is mediated only by the plasmalemma H+-ATPase. Fusicoccin stimulated the plasmalemma H+-ATPase - i.e. Mg:ATP-dependent intravesicular acidification, hyperpolaryzation of delta psi and ATPase activity -, when these activities were measured at the physiologically relevant pHs of 7.3 to 7.6. No effect of FC on the plasmalemma H+-ATPase was evident at pH 6.6.
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PMID:Fusicoccin stimulates the H+-ATPase of plasmalemma in isolated membrane vesicles from radish. 286 69

Fusicoccin affects several physiological processes regulated by the plasma membrane H(+)-ATPase in higher plants while other organisms having P-type H(+)-ATPases (e.g., fungi) are fusicoccin-insensitive. We have previously shown that fusicoccin binding to its receptor is necessary for H(+)-ATPase stimulation and have achieved the functional reconstitution into liposomes of fusicoccin receptors and the H(+)-ATPase from maize. In this paper we show that fusicoccin sensitivity can be conferred on the H(+)-ATPase from Neurospora crassa, a fungus insensitive to fusicoccin. In fact, H+ pumping by purified H(+)-ATPase from Neurospora crassa reconstituted into liposomes containing crude or partially purified fusicoccin receptors from maize was markedly enhanced by fusicoccin. The stimulation of H+ pumping by fusicoccin is dependent upon pH, fusicoccin, and protein concentration, as was reported for the system reconstituted with both proteins from maize.
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PMID:The fungal H(+)-ATPase from Neurospora crassa reconstituted with fusicoccin receptors senses fusicoccin signal. 787 25

Fusicoccin (FC) is a fungal toxin that activates the plant plasma membrane H+-ATPase by binding with 14-3-3 proteins, causing membrane hyperpolarization. Here we report on the effect of FC on a gene-for-gene pathogen-resistance response and show that FC application induces the expression of several genes involved in plant responses to pathogens. Ten members of the FC-binding 14-3-3 protein gene family were isolated from tomato (Lycopersicon esculentum) to characterize their role in defense responses. Sequence analysis is suggestive of common biochemical functions for these tomato 14-3-3 proteins, but their genes showed different expression patterns in leaves after challenges. Different specific subsets of 14-3-3 genes were induced after treatment with FC and during a gene-for-gene resistance response. Possible roles for the H+-ATPase and 14-3-3 proteins in responses to pathogens are discussed.
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PMID:Fusicoccin, 14-3-3 proteins, and defense responses in tomato plants. 1019 82

The physiological mechanisms underlying leaf growth inhibition under salt stress are not fully understood. Apoplastic pH is considered to play an important role in cell wall loosening and tissue growth and was demonstrated to be altered by several growth-limiting environmental conditions. In this study we have evaluated the possibility that inhibition of maize (Zea mays) leaf elongation by salinity is mediated by changes in growing cell wall acidification capacity. The kinetics of extended apoplast pH changes by leaf tissue of known expansion rates and extent of growth reduction under stress was investigated (in vivo) and was found similar for non-stressed and salt-stressed tissues at all examined apoplast salinity levels (0.1, 5, 10, or 25 mM NaCl). A similar rate of spontaneous acidification for the salt and control treatments was demonstrated also in in situ experiments. Unlike growing cells that acidified the external medium, mature nongrowing cells caused medium alkalinization. The kinetics of pH changes by mature tissue was also unchanged by salt stress. Fusicoccin, an enhancer of plasmalemma H(+)-ATPase activity level, greatly stimulated elongation growth and acidification rate to a similar extent in the control and salt treatments. That the ability of the growing tissue to acidify the apoplast did not change under same salt stress conditions that induced inhibition of tissue elongation rate suggests that salinity does not inhibit cell growth by impairing the acidification process or reducing the inherent capacity for cell wall acidification.
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PMID:Salinity-induced inhibition of leaf elongation in maize is not mediated by changes in cell wall acidification capacity. 1124 21

A 14-3-3 protein has been cloned and sequenced from a cDNA library constructed from mRNAs of mature pollen grains of Lilium longiflorum Thunb. Monoclonal antibodies (MUP 5 or MUP 15) highly specific against 14-3-3 proteins recognised a 30-kDa protein in the cytoplasmic fraction of many various lily tissues (leaves, bulbs, stems, anther filaments, pollen grains, stigmas) and in other plants (Arabidopsis seedlings, barley recombinant 14-3-3). In addition, 14-3-3 proteins were detected in a microsomal fraction isolated from pollen grains and tubes, and the amount of membrane-bound 14-3-3 proteins as well as the amount of the plasma membrane (PM) H+ ATPase increased during germination of pollen grains and tube growth. No change was observed in the cytoplasmic fraction. A further increase in the amount of 14-3-3 proteins in the microsomal fraction was observed when pollen grains were incubated in germination medium containing 1 microM fusicoccin (FC) whereas the number of 14-3-3s in the cytoplasmic fraction decreased. Fusicoccin also protected membrane-bound 14-3-3 proteins from dissociation after washing with the chaotropic salt KI. Furthermore, FC stimulated the PM H+ ATPase activity, the germination frequency and the growth rate of pollen tubes, thus indicating that a modulation of the PM H+ ATPase activity by interaction with 14-3-3 proteins may regulate germination and tube growth of lily pollen.
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PMID:Molecular and physiological characterisation of a 14-3-3 protein from lily pollen grains regulating the activity of the plasma membrane H+ ATPase during pollen grain germination and tube growth. 1152 49

Fusicoccin (FC), a fungal phytotoxin, stimulates the H(+) -ATPase located in the plasma membrane (PM) of higher plants. The first event in the reaction chain leading to enhanced H(+) -efflux seems to be the binding of FC to a FC-binding protein (FCBP) in the PM. We solubilized 90% of the FCBP from oat (Avena sativa L. cv Victory) root PM in an active form with 1% octyl-glucoside. The FCBP was stabilized by the presence of protease inhibitors. The FCBP was purified by affinity chromatography using FC-linked adipic acid dihydrazide agarose (FC-AADA). Upon elution with 8 molar urea, two major protein bands on sodium dodecyl sulfate-polyaerylamide gel electrophoresis with molecular weights of 29,700 and 31,000 were obtained. Successive chromatography on BBAB Bio-Gel A, hexyl agarose, and FC-AADA resulted in the same two bands when the FC-AADA was eluted with sodium dodecyl sulfate. A direct correlation was made between 3H-FC-binding activity and the presence of the two protein bands. The stoichiometry of the 29,700 and 31,000 molecular weight bands was 1:2. This suggests that the FCBP occurs in the native form as a heterotrimer with an apparent molecular weight of approximately 92,000.
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PMID:Purification and identification of the fusicoccin binding protein from oat root plasma membrane. 1153 48

14-3-3 proteins interact with a novel phosphothreonine motif (Y(946)pTV) at the extreme C-terminal end of the plant plasma membrane H(+)-ATPase molecule. Phosphorylation-independent binding of 14-3-3 protein to the YTV motif can be induced by the fungal phytotoxin fusicoccin. The molecular basis for the phosphorylation-independent interaction between 14-3-3 and H(+)-ATPase in the presence of fusicoccin has been investigated in more detail. Fusicoccin binds to a heteromeric receptor that involves both 14-3-3 protein and H(+)-ATPase. Binding of fusicoccin is dependent upon the YTV motif in the H(+)-ATPase and, in addition, requires residues further upstream of this motif. Apparently, 14-3-3 proteins interact with the unusual epitope in H(+)-ATPase via its conserved amphipathic groove. This implies that very diverse epitopes bind to a common structure in the 14-3-3 protein.
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PMID:Phosphorylation-independent interaction between 14-3-3 protein and the plant plasma membrane H+-ATPase. 1219 5

Blue-light (BL)-dependent H+ pumping in guard-cell protoplasts (GCPs) from Vicia faba was inhibited by 65% in the presence of abscisic acid (ABA). The inhibition increased with the time after application of ABA and was concentration dependent with a saturating concentration of 1 [mu]M at pH 6.2. The inhibition was nearly independent of the pH of the medium in the range 5.4 to 7.2 when ABA was applied at 10 [mu]M, whereas it was dependent on pH when the ABA concentration was decreased. The protonated form of ABA was saturating at 40 nM in inhibiting BL-dependent H+ pumping under various experimental conditions, whereas the dissociated form at 500 nM had no inhibitory effect on the pumping, suggesting that the protonated form of ABA is the form active in inhibiting the pumping. Fusicoccin (10 [mu]M), an activator of plasma membrane H+-ATPase, induced H+ pumping from GCPs, and the rate of H+ pumping was decreased to 70% by ABA. In contrast, ABA did not inhibit H+ pumping in isolated microsome vesicles from GCPs. These results suggest that the inhibition of BL-dependent H+ pumping by ABA in GCPs may be due to indirect inactivation of plasma membrane H+-ATPase and/or inhibition of the BL-signaling pathway. The pump inhibition by ABA causes membrane depolarization and can be an initial step to induce stomatal closure and reduces the transpirational water loss under drought stress in the daytime.
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PMID:Inhibition of Blue Light-Dependent H+ Pumping by Abscisic Acid in Vicia Guard-Cell Protoplasts. 1222 99

The fungal phytotoxin fusicoccin affects various transport processes in the plasma membrane of plant cells. The plasma membrane (PM) H+-ATPase (EC 3.6.1.35) seems to be the primary target of fusicoccin action. The kinetics of the stimulation of the PM H+-ATPase by fusicoccin was studied in PM vesicles isolated from oat (Avena sativa cv Adamo) roots by aqueous two-phase partitioning. Considerable stimulation of activity was observed only when roots were treated with fusicoccin prior to the PM isolation. Fusicoccin treatment shifted the pH optimum of the ATPase toward more alkaline values and increased Vmax. No effects on Km were observed. Treatment with trypsin resulted in stimulation of ATPase activity in control vesicles but not in the fusicoccin-treated vesicles. The characteristics of stimulation by trypsin in control vesicles were comparable with those of stimulation by fusicoccin. This result and the change of the polypeptide pattern on western blots suggest the involvement of the C-terminal inhibitory domain in the fusicoccin signal transduction chain. On the other hand, stimulation by lyso-PC demonstrated other characteristics than stimulation by fusicoccin. Lyso-PC was able to stimulate ATPase activity at both acidic and alkaline pH values. Kinetic analysis of the pH dependency curves revealed different mechanisms for activation by fusicoccin and by lyso-PC. Whereas fusicoccin shifted the pH dependency of formation of phosphorylated intermediate to more alkaline values, lyso-PC seemed to increase dephosphorylation independently of pH.
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PMID:Modulation of H+-ATPase Activity by Fusicoccin in Plasma Membrane Vesicles from Oat (Avena sativa L.) Roots (A Comparison of Modulation by Fusicoccin, Trypsin, and Lysophosphatidylcholine). 1223 67

Fusicoccin (FC), an activator of the plant plasma membrane H+-ATPase, induces several components of plant pathogen resistance responses, including defence hormone biosynthesis and pathogenesis-related (PR) gene expression. The mechanism by which these responses occur, and the effect they have on plant-pathogen interactions is unknown. Here, we show that PR gene expression in response to FC in tomato (Lycopersicon esculentum Mill.) plants does not strictly require the common defence hormones, salicylic acid, jasmonic acid and ethylene. We also show that FC-induced PR gene expression requires neither Ca2+ nor reactive oxygen species, typical early pathogen-resistance response signals. The possibility that PR gene expression is related to FC-induced dehydration stress is also discounted. Finally, we show that the defence responses elicited by FC in tomato are not sufficient to confer resistance to the bacterial pathogen Pseudomonas syringae. Rather, FC increases the rate and severity of disease symptom formation in an ethylene-dependent manner.
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PMID:Fusicoccin activates pathogen-responsive gene expression independently of common resistance signalling pathways, but increases disease symptoms in Pseudomonas syringae-infected tomato plants. 1501 97


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