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

---

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

The plasma membrane of higher plants contains a H(+)-ATPase as its major ion pump. This enzyme belongs to the P-type family of cation-translocating enzymes and generates the proton-motive force that drives solute uptake across the plasma membrane. In Arabidopsis thaliana the plasma membrane H(+)-ATPase is encoded by a multigene family (Harper, J. F., Surowy, T. K., and Sussman, M. R. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 1234-1238). The complete genomic sequence of a third Arabidopsis H(+)-ATPase isoform (referred to as AHA2) is presented here, and the predicted protein sequence is compared with previously published AHA1, AHA3, and tobacco Nicotiana plumbaginifolia NP1 isoforms. The AHA2 gene is most similar to AHA1, with predicted proteins containing 95% amino acid identity. The mRNA start site and 5'-untranslated sequence for AHA2 were determined from cDNA amplified by the polymerase chain reaction. The 5' region contains a 23-base pair (bp) polypyrimidine sequence and a short upstream reading frame. In comparison with the 16 introns reported in AHA3, AHA2 is missing one intron in the 5'-untranslated region and a second intron in the C-terminal coding region. An unusually large intron for Arabidopsis (greater than 1000 bp) is present at the beginning of the coding sequence of both AHA2 and AHA3. In the 3'-untranslated sequence of AHA1 and AHA2 but not AHA3, there is a 65-bp region of 85% identity and a second shorter region of 16-bp identity harboring an unusual putative poly(A) addition signal (dTTTGAAGAAACAAGGC). Northern blot analysis indicates that AHA2 mRNA relative to total cellular RNA is expressed at significantly higher levels in root tissue as compared with shoot tissue.
...
PMID:The Arabidopsis thaliana plasma membrane H(+)-ATPase multigene family. Genomic sequence and expression of a third isoform. 214 86

To examine the functional properties of the three major isoforms of plasma membrane H(+)-ATPase expressed in Arabidopsis thaliana (AHA1, AHA2, and AHA3), we employed a system for the heterologous expression of functional plant plasma membrane H(+)-ATPase in yeast (Villalba, J. M., Palmgren, M. G., Berberian, G. E., Ferguson, C., and Serrano, R. (1992) J. Biol. Chem. 267, 12341-12349). Each isoform was expressed efficiently but appeared to be retained in the endoplasmic reticulum of yeast. All isoforms displayed qualitatively similar enzymatic properties, but quantitative differences were found. When compared with AHA3, AHA1 and AHA2 had an apparent higher turnover rate for ATP hydrolysis, exhibited a 10-fold higher apparent affinity for ATP, and a 3-fold higher sensitivity toward vanadate. In addition, AHA2 had a slightly lower apparent affinity for H+ and seemed to be more susceptible to activation by lysophosphatidylcholine than did AHA1 and AHA3. This study represents the first comparison of the functional properties of isoforms of the plant plasma membrane H(+)-ATPase.
...
PMID:Functional comparisons between plant plasma membrane H(+)-ATPase isoforms expressed in yeast. 830 Jun 35

Transport across the plasma membrane is driven by an electrochemical gradient of H+ ions generated by the plasma membrane proton pump (H(+)-ATPase). Random mutants of Arabidopsis H(+)-ATPase AHA1 were isolated by phenotypic selection of growth of transformed yeast cells in the absence of endogenous yeast H(+)-ATPase (PMA1). A Trp-874-Leu substitution as well as a Trp-874 to Lys-935 deletion in the hydrophilic C-terminal domain of AHA1 conferred growth of yeast cells devoid of PMA1. A Trp-874-Phe substitution in AHA1 was produced gy site-directed mutagenesis. The modified enzymes hydrolyzed ATP at 200-500% of wild-type level, had a sixfold increase in affinity for ATP (from 1.2 to 0.2 mM; pH 7.0), and had the acidic pH optimum shifted towards neutral pH. AHA1 did not contribute significantly to H+ extrusion by transformed yeast cells. The different specifies of aha1, however, displayed marked differences in initial rates of net H+ extrusion and in their ability to sustain an electrochemical H+ gradient. These results provide evidence that Trp-874 plays an important role in auto-inhibition of the plant H(+)-ATPase and may be involved in controlling the degree of coupling between ATP hydrolysis and H+ pumping. Finally, these results demonstrate the usefulness of yeast as a generalized screening tool for isolating regulatory mutants of plant transporters.
...
PMID:Modified plant plasma membrane H(+)-ATPase with improved transport coupling efficiency identified by mutant selection in yeast. 881 59

The plant plasma membrane H(+)-ATPase energizes the secondary uptake of nutrients and may facilitate cell expansion by acidifying the cell wall. In yeast, Glc stimulates the accumulation of H(+)-ATPase mRNA, and the growth rate supported by various sugars is correlated with H(+)-ATPase protein abundance. Expression of three H(+)-ATPase genes, LHA1, LHA2, and LHA4, was previously detected in tomato (Lycopersicon esculentum). We have characterized the sequence of the LHA4 gene and examined the expression of these three tomato H(+)-ATPase genes in growing tissues and in response to exogenous sugars. LHA4 is a member of the H(+)-ATPase subfamily, including the Arabidopsis thaliana genes AHA1, AHA2, and AHA3. The 5' untranslated region of the deduced LHA4 cDNA contains a short, open reading frame very similar to that in the Nicotiana plumbaginifolia gene PMA1. LHA4 transcript abundance in seedlings is correlated with cell growth, being 2.5 times greater in hypocotyls of dark- versus light-grown plants. The accumulation of both LHA4 and LHA2 mRNAs is induced by the addition of exogenous sugars and this induction appears to be dependent on sugar uptake and metabolism, because mannitol and 3-O-methylglucose do not stimulate mRNA accumulation. These results suggest that the induction of expression of H(+)-ATPase genes by metabolizable sugars may be part of a generalized cellular response to increased cell growth and metabolism promoted by the availability of an abundant carbon source.
...
PMID:Sugar regulates mRNA abundance of H(+)-ATPase gene family members in tomato. 893 20

Legume nodules have specialized transport functions for the exchange of carbon and nitrogen compounds between bacteroids and root cells. Plasma membrane-type (vanadate-sensitive) H+-ATPase energizes secondary active transporters in plant cells and it could drive exchanges across peribacteroidal and plasmatic membranes. A nodule cDNA corresponding to a major isoform of Phaseolus vulgaris H+-ATPase (designated BHA1) has been cloned. BHA1 is a functional proton pump because after removal of its inhibitory domain and can complement a yeast mutant unable to synthesize a H+-ATPase. BHA1 is not nodule-specific, since it is also expressed in roots of uninfected plants. It belongs to the subfamily of plasma membrane H+-ATPases defined by the Arabidopsis AHA1, AHA2 and AHA3 genes and the tobacco PMA4 and corn MHA2 genes. In situ hybridization in nodule sections indicates high expression of BHA1 limited to uninfected cells. These results were confirmed by immunocytochemistry. The relatively low expression of plasma membrane-type H+-ATPase in Rhizobium-infected cells put a note of caution on the origin of the vanadate-sensitive ATPase described in preparations of peribacteroidal membranes. Also, our results indicate that active transport in symbiotic nodules is most intense at the plasma membrane of uninfected cells and support a specialized role of uninfected tissue for nitrogen transport.
...
PMID:Localization of plasma membrane H+-ATPase in nodules of Phaseolus vulgaris L. 900 3

A nontoxic and simple staining method for the detection of DNA in agarose gels is described. After eletrophoretic separation, the gels were stained with 5 microg/ml of berberine (BB) prepared in distilled water and then the gels were soaked in 20 microg/ml of aqueous Mordant Yellow 3R (MY3R) solution. Employment of MY3R as a counterion dye efficiently quenched unwanted background fluorescence of BB. This method can detect as little as 10 ng of plasma membrane H(+)-ATPase cDNA obtained from Arabidopsis thaliana L. (AHA1, 3.2 kb) under a long wavelength of UV irradiation (366 nm) within 1 h.
...
PMID:Detection of DNA in agarose gels using berberine and Mordant Yellow 3R. 1041 96

Although a well ascertained evidence proves that the activity of the plant plasma membrane H(+)-ATPase is regulated by 14-3-3 proteins, information about physiological factors modulating the phosphorylation-dependent association between 14-3-3 proteins and the proton pump is largely incomplete. In this paper we show that the 5'-AMP-mimetic, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), inhibits the fusicoccin-promoted proton extrusion in maize roots. We also demonstrate that 5'-AMP inhibits the association of 14-3-3 proteins with the C-terminal domain of the H(+)-ATPase in an overlay assay as well as the 14-3-3-dependent stimulation of the Arabidopsis thaliana H(+)-ATPase AHA1 isoform expressed in yeast membranes. Finally, by means of affinity chromatography with immobilized 5'-AMP and trinitrophenyl-AMP fluorescence analysis, we demonstrate that the 14-3-3 isoform GF14-6 from maize is able to bind 5'-AMP. The possible role of 5'-AMP as a general regulator of 14-3-3 functions in the plant cell is discussed.
...
PMID:Adenosine 5'-monophosphate inhibits the association of 14-3-3 proteins with the plant plasma membrane H(+)-ATPase. 1142 44

Using the two-hybrid technique we identified a novel protein whose N-terminal 88 amino acids (aa) interact with the C-terminal regulatory domain of the plasma membrane (PM) H+-ATPase from Arabidopsis thaliana (aa 847-949 of isoform AHA1). The corresponding gene has been named Ppi1 for Proton pump interactor 1. The encoded protein is 612 aa long and rich in charged and polar residues, except for the extreme C-terminus, where it presents a hydrophobic stretch of 24 aa. Several genes in the A. thaliana genome and many ESTs from different plant species share significant similarity (50-70% at the aa level over stretches of 200-600 aa) to Ppi1. The PPI1 N-terminus, expressed in bacteria as a fusion protein with either GST or a His-tag, binds the PM H+-ATPase in overlay experiments. The same fusion proteins and the entire coding region fused to GST stimulate H+-ATPase activity. The effect of the His-tagged peptide is synergistic with that of fusicoccin (FC) and of tryptic removal of a C-terminal 10 kDa fragment. The His-tagged peptide binds also the trypsinised H+-ATPase. Altogether these results indicate that PPI1 N-terminus is able to modulate the PM H+-ATPase activity by binding to a site different from the 14-3-3 binding site and is located upstream of the trypsin cleavage site.
...
PMID:A novel interaction partner for the C-terminus of Arabidopsis thaliana plasma membrane H+-ATPase (AHA1 isoform): site and mechanism of action on H+-ATPase activity differ from those of 14-3-3 proteins. 1218 6

We investigated the nature of the complex ATP activation kinetics of plant H+-ATPases. To this aim we analyzed that activation in three isolated isoforms (AHA1, AHA2, and AHA3) of H+-ATPase from Arabidopsis thaliana. The isoforms were obtained by heterologous expression in endoplasmic reticulum of yeast. ATP stimulation was always with low affinity (K0.5 between 500 and 1800 [mu]M). In addition, the curves were not Michaelian and displayed positive cooperativity. Detailed studies with AHA2 showed that (a) enzyme solubilized with lysophosphatidylcholine exhibited Michaelian behavior even in the presence of soybean lecithin liposomes free of enzyme, (b) solubilized enzyme incorporated into the same liposomes displayed two-site kinetics with negative cooperativity, and (c) enzyme partially digested with trypsin lost the C-terminal portion of the molecule. Under this condition the ATP activation kinetics was Michaelian or had a slight negative cooperativity and the K0.5ATP was reduced 3-fold. These data suggest that the functional unit of the H+-ATPase has two catalytic ATP sites with variable cooperativity and kinetics competence of the E(ATP) and E(ATP)2 complexes. Such variability is likely modulated by the association of the enzyme with membrane structures and by a regulatory domain in the C terminus of the enzyme molecule.
...
PMID:Evidence for Two Catalytic Sites in the Functional Unit of H+-ATPase from Higher Plants. 1222 12

The plasma membrane H(+)-ATPase is activated by binding of 14-3-3 protein to the phosphorylated C terminus. Considering the large number of 14-3-3 and H(+)-ATPase isoforms in Arabidopsis (13 and 11 expressed genes, respectively), specificity in binding may exist between 14-3-3 and H(+)-ATPase isoforms. We now show that the H(+)-ATPase is the main target for 14-3-3 binding at the plasma membrane, and that all twelve 14-3-3 isoforms tested bind to the H(+)-ATPase in vitro. Using specific antibodies for nine of the 14-3-3 isoforms, we show that GF14epsilon, mu, lambda, omega, chi, phi, nu, and upsilon are present in leaves, but that isolated plasma membranes lack GF14chi, phi and upsilon. Northern blots using isoform-specific probes for all 14-3-3 and H(+)-ATPase isoforms showed that transcripts were present for most of the isoforms. Based on mRNA levels, GF14epsilon, mu, lambda and chi are highly expressed 14-3-3 isoforms, and AHA1, 3, and 11 highly expressed H(+)-ATPase isoforms in leaves. However, mass peptide fingerprinting identified AHA1 and 2 with the highest score, and their presence could be confirmed by MS/MS. It may be calculated that under 'unstressed' conditions less than one percent of total 14-3-3 is attached to the H(+)-ATPase. However, during a condition requiring full activation of H+ pumping, as induced here by the presence of the fungal toxin fusicoccin, several percent of total 14-3-3 may be engaged in activation of the H(+)-ATPase.
...
PMID:Plasma membrane H(+)-ATPase and 14-3-3 isoforms of Arabidopsis leaves: evidence for isoform specificity in the 14-3-3/H(+)-ATPase interaction. 1550 43


1 2 3 4 5 Next >>

---