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)

Elicitor preparations containing the avr5 gene products from race 4 of Cladosporium fulvum and tomato (Lycopersicon esculentum L.) cells near isogenic for the resistance gene Cf5 were used to investigate events following the treatment of host plasma membranes with elicitor. A 4-fold increase in H+-ATPase activity, coincident with the acidification of the extracellular medium, was detected immediately after elicitor treatment. The elicitor-induced stimulation of the plasma membrane H+-ATPase was inhibited by okadaic acid but not by staurosporine, suggesting that protein dephosphorylation was required for increased H+-ATPase activity. This observation was confirmed by [gamma]-32P labeling and immunodetection of the plasma membrane H+-ATPase. Effects of guanidine nucleotide analogs and mastoparan on the ATPase activity suggested the role of GTP-binding proteins in mediating the putative elicitor-receptor binding, resulting in activation of a phosphatase(s), which in turn stimulates the plasma membrane H+-ATPase by dephosphorylation.
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PMID:Plant Defense Response to Fungal Pathogens (Activation of Host-Plasma Membrane H+-ATPase by Elicitor-Induced Enzyme Dephosphorylation). 1223 73

Kidneys from winter bats (Myotis lucifugus) were removed and fixed in cold formalin-calcium while the animals were in the following states: (a) natural hibernation; (b) arousal from hibernation for 24 hours; (c) laboratory maintained hibernation; and (d) no hibernation since the previous winter. With fixed frozen sections, the lead salt method of Wachstein and Meisel with adenosine triphosphate as substrate (pH 7.2) showed enzymic activity localized in large vacuoles and smaller vesicles or droplets in the Golgi region of distal and proximal tubular epithelial cells of kidneys from hibernating bats. No ATPase activity was detected in the basal lamellae of tubular epithelium from hibernating bats. ATPase activity in the Golgi region was not seen in cells from kidney tubules of bats aroused from hibernation 24 hours previously or of animals that had not hibernated, whereas activity for ATPase was present in the basal infoldings of tubular epithelium from these animals. Inosine di- and triphosphatase and calcium activated ATPase activities were also detected in the Golgi region of hibernating bats but were not present in the basal infoldings of tubular epithelium from active animals. There was little or no activity toward the mono- and diphosphates of adenine, thiamine pyrophosphate, and the di- or triphosphates of guanidine, cytidine, or deoxyadenosine. The loss of enzymic activity from the Golgi region of the tubular epithelium from hibernating bats and its increase in the region of the basal infoldings of tubular epithelium in aroused bats suggests that the Golgi region plays a role in the synthesis of enzymic protein usually identified with the external cell membrane.
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PMID:CYTOCHEMICAL DIFFERENCES IN KIDNEYS FROM WINTER HIBERNATING AND AROUSED BATS (MYOTIS LUCIFUGUS), WITH PARTICULAR REFERENCE TO THE GOLGI ZONE. 1418 9

The effect of lipid peroxidation product 4-hydroxy-2-nonenal (HNE) on the protein conformation of porcine cerebral cortex Na(+)-K(+)-ATPase was examined in term of the intrinsic tryptophanyl fluorescence measurement. Treatment of ATPase with HNE resulted in a decrease in the fluorescence intensity and an increase in the fluorescence anisotropy in a concentration-dependent manner. The difference in the fluorescence intensity and fluorescence anisotropy observed between the control and HNE-modified ATPase completely disappeared after treatment of the protein with guanidine hydrochloride (1 M). These results suggest that HNE-modification of the Na(+)-K(+)-ATPase induces alterations in the conformation of the enzyme molecule. This interpretation was further supported by a decrease in fluorescence quenching efficiency with acrylamide and sulfhydryl (SH) content. The decrease in quenching efficiency suggests that the proximity of the quencher molecule to the fluorophores located in the enzyme is suppressed. Modification of the enzyme with N-ethylmaleimide (NEM) also resulted in a decrease in quenching efficiency with the loss of SH groups. Furthermore, a good relationship between the SH content and these fluorescence parameters (fluorescence anisotropy and quenching efficiency) were observed. On the other hand, treatment of the Na(+)-K(+)-ATPase with other aldehydes such as malondialdehyde (MDA), 1-hexanal and nonanal did not affect either the quenching efficiency or SH content. Based on these results, the possibility of alterations in the physical properties of the Na(+)-K(+)-ATPase associated with modification by HNE has been discussed.
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PMID:Increase in molecular rigidity of the protein conformation of brain Na+-K+-ATPase by modification with 4-hydroxy-2-nonenal. 1464 65

The protein RecA is involved in homologous recombination, DNA repair and also catalyzes DNA strand exchange. RecX gene is downstream of recA and the gene product RecX is supposed to be important for RecA regulation. Recombinant RecX is purified to homogeneity, and circular dichroism (CD) and FTIR spectroscopy show the protein to exist mostly in helical conformation. The fluorescence emission maxima of the native and the denatured protein and the steady-state fluorescence quenching studies with acrylamide indicate the presence of tryptophan residues partially exposed to the bulk solvent. Denaturation studies with urea and guanidine hydrochloride by use of spectroscopic methods, fluorescence, and CD also confirm the instability of the protein and unfolding occurs following a two-state model. Mass spectrometry and gel permeation chromatography suggest the monomeric form of the protein. Molecular modeling of RecX represents the molecule as extended and helical bundle in conformity with the spectroscopic results. To understand the mechanism of RecX in the regulation of RecA the structural model of RecA-RecX has been discussed. In this proposed model, entry of RecX into hexameric RecA filament prevents binding of ssDNA and also inhibits ATPase activity.
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PMID:Molecular modeling of RecX reveals its mode of interaction with RecA. 1468 Aug 9

A series of substituted guanidine derivatives were prepared and evaluated as potent and selective inhibitors of mitochondrial F(1)F(0) ATP hydrolase. The initial thiourethane derived lead molecules possessed intriguing in vitro pharmacological profiles, though contained moieties considered non-drug-like. Analogue synthesis efforts led to compounds with maintained potency and superior physical properties. Small molecules in this series which potently and selectivity inhibit ATP hydrolase and not ATP synthase may have utility as cardioprotective agents.
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PMID:N-[1-Aryl-2-(1-imidazolo)ethyl]-guanidine derivatives as potent inhibitors of the bovine mitochondrial F1F0 ATP hydrolase. 1501 16

Phospholamban (PLB) and sarcolipin (SLN) are small integral membrane proteins that regulate the Ca(2+)-ATPases of cardiac and skeletal muscle, respectively, and directly alter their calcium transport properties. PLB interacts with and regulates the cardiac Ca(2+)-ATPase at submaximal calcium concentrations, thereby slowing relaxation rates and reducing contractility in the heart. SLN interacts with and regulates the skeletal muscle Ca(2+)-ATPase in a mechanism analogous to that used by PLB. While these regulatory interactions are biochemically and physiologically well characterized, structural details are lacking. To pursue structural studies, such as electron cryo-microscopy and X-ray crystallography, large quantities of over-expressed and purified protein are required. Herein, we report a modified method for producing large quantities of PLB and SLN in a rapid and efficient manner. Briefly, recombinant wild-type PLB and SLN were over-produced in Escherichia coli as maltose binding protein fusion proteins. A tobacco etch virus protease site allowed specific cleavage of the fusion protein and release of recombinant PLB or SLN. Selective solubilization with guanidine-hydrochloride followed by reverse-phase HPLC permitted the rapid, large-scale production of highly pure protein. Reconstitution and measurement of ATPase activity confirmed the functional interaction between our recombinant regulatory proteins and Ca(2+)-ATPase. The inhibitory properties of the over-produced proteins were consistent with previous studies, where the inhibition was relieved by elevated calcium concentrations. In addition, we show that our recombinant PLB and SLN are suitable for high-resolution structural studies.
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PMID:Rapid, high-yield expression and purification of Ca2+-ATPase regulatory proteins for high-resolution structural studies. 1572 79

alpha-Tropomyosin (Tm) is a two-stranded alpha-helical coiled-coil protein, which participates in the regulation of muscle contraction. Unlike Tm purified from vertebrate muscle, recombinant Tm expressed in Escherichia coli is not acetylated at the N-terminal residue and loses the capacity to undergo head-to-tail polymerization, to bind actin and to inhibit actomyosin ATPase activity. These functions are restored by fusion of an N-terminal Ala-Ser (AS) dipeptide tail to recombinant Tm. Here, we have employed chemical (guanidine hydrochloride and urea) and physical (elevated hydrostatic pressures and low temperatures) denaturing agents to compare the structural stabilities of polymeric alanine-serine-tropomyosin (ASTm, containing the AS dipeptide) and dimeric "non-fusion" Tm (nfTm, i.e., not containing the AS dipeptide). Binding of the hydrophobic fluorescent dye bis-ANS, circular dichroism and size-exclusion chromatography were used to monitor the stabilities and state of association of both proteins under different solution conditions. Bis-ANS binding was markedly decreased at low concentrations (<1M) of GdnHCl or urea, whereas the secondary structures of both ASTm and nfTm were essentially unaffected in the same range of denaturant concentrations. These results suggest local unfolding of bis-ANS binding domains prior to global unfolding of Tm. In contrast, increased bis-ANS binding was observed when Tm was submitted to high pressures or to low temperatures, implying increased exposure of hydrophobic domains in the protein. Taken together, the different sensitivities of ASTm and nfTm to different denaturing agents support the notion that, at close to physiological conditions, head-to-tail interactions in polymerized ASTm are predominantly stabilized by electrostatic interactions between adjacent Tm dimers, whereas non-polar interactions appear to play a major role in the stability of the coiled-coil structure of individual Tm dimers.
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PMID:Folding and stability of a coiled-coil investigated using chemical and physical denaturing agents: comparative analysis of polymerized and non-polymerized forms of alpha-tropomyosin. 1583 71

The effect of guanidine hydrochloride on ATPase activity, gel filtration, turbidity, and the fluorescence emission intensity of mitochondrial F1-ATPase was examined. Purified F1 from bovine heart mitochondria was slowly inactivated at low denaturant concentration, and inactivation was associated with delta and epsilon subunit dissociation. delta and epsilon subunits were bound together to form a stable and soluble heterodimer. In parallel, appearance of turbidity was observed. This was caused by the formation of alpha3beta3gamma non-covalent aggregates, as analyzed by SDS-PAGE. Short periods of exposition of the F1 complex to high concentrations of guanidine hydrochloride (0.8-3 M) again induced deltaepsilon dissociation as a heterodimer and the formation of an inactive alpha3beta3gamma subcomplex. This eventually dissociated progressively into single subunits caused by partial unfolding, as evidenced through changes of the protein intrinsic fluorescence emission. Our results suggest that the delta and epsilon subunits are loosely bound to alpha3beta3gamma , and play an important role in determining structural stability to isolated mitochondrial F1-ATPase.
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PMID:Guanidine-induced dissociation of mitochondrial F1-ATPase. 1599 7

A novel ATPase activity that was strongly activated in the presence of either cobalt or manganese ion was discovered in the chaperonin from hyperthermophilic Pyrococcus furiosus (Pfu-cpn). Surprisingly, a significant ADPase activity was also detected under the same conditions. A more extensive search revealed similar nucleotide hydrolysis activities in other thermostable chaperonins. Chaperonin activity, i.e., thermal stabilization and refolding of malate dehydrogenase from the guanidine-hydrochloride unfolded state were also detected for Pfu-cpn under the same conditions. We propose that the novel cobalt/manganese-dependent ATP/ADPase activity may be a common trait of various thermostable chaperonins.
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PMID:A novel ATP/ADP hydrolysis activity of hyperthermostable group II chaperonin in the presence of cobalt or manganese ion. 1634 86

The molecular chaperone Hsp104 is not only a key component of the cellular machinery induced to disassemble aggregated proteins in stressed cells of Saccharomyces cerevisiae but also plays an essential role in the propagation of the [PSI+], [URE3], and [RNQ/PIN+] prions in this organism. Here we demonstrate that the fungal pathogen Candida albicans carries an 899-residue stress-inducible orthologue of Hsp104 (CaHsp104) that shows a high degree of amino acid identity to S. cerevisiae Hsp104 (ScHsp104). This identity is significantly lower in the N- and C-terminal regions implicated in substrate recognition and cofactor binding, respectively. CaHsp104 is able to provide all known functions of ScHsp104 in an S. cerevisiae hsp104 null mutant, i.e., tolerance to high-temperature stress, reactivation of heat-denatured proteins, and propagation of the [PSI+] prion. As also observed for ScHsp104, overexpression of CaHsp104 leads to a loss of the [PSI+] prion. However, unlike that of ScHsp104, CaHsp104 function is resistant to guanidine hydrochloride (GdnHCl), an inhibitor of the ATPase activity of this chaperone. These findings have implications both in terms of the mechanism of inhibition of Hsp104 by GdnHCl and in the evolution of the ability of fungal species to propagate prions.
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PMID:The [PSI+] prion of Saccharomyces cerevisiae can be propagated by an Hsp104 orthologue from Candida albicans. 1646 63


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