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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bacterial conjugation is an example of macromolecular trafficking between cells, based on the translocation of single-stranded DNA across membranes through a type IV secretion system. TrwBDeltaN70 is the soluble domain of TrwB, an essential integral membrane protein that couples the relaxosome (a nucleoprotein complex) to the DNA transport apparatus in plasmid R388 conjugation. TrwBDeltaN70 crystallographic structure revealed a hexamer with six equivalent subunits and a central channel. In this work, we characterize a DNA-dependent ATPase activity for TrwBDeltaN70. The protein displays positive cooperativity for ATP hydrolysis, with at least three catalytic sites involved. The activity is sensitive to pH and salt concentration, being more active at low pH values. The effective oligonucleotide size required for activation of the ATPase function is between 40 and 45 nucleotides, and the same length is required for the formation of high-molecular-weight TrwBDeltaN70-DNA complexes, as observed by gel filtration chromatography. A mutation in a tryptophan residue (W216A), placed in the central pore formed by the hexameric structure, resulted in a protein that did not hydrolyze ATP. In addition, it exerted a dominant negative effect, both on R388 conjugation frequency and ATP hydrolysis, underscoring the multimeric state of the protein. ATP hydrolysis was not coupled to a DNA unwinding activity under the tested conditions, which included forked DNA substrates. These results, together with TrwB structural similarity to F1-ATPase, lead us to propose a mechanism for TrwB as a DNA-translocating motor.
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PMID:TrwB, the coupling protein involved in DNA transport during bacterial conjugation, is a DNA-dependent ATPase. 1591 15

Natronomonas pharaonis is an extremely haloalkaliphilic archaeon that was isolated from salt-saturated lakes of pH 11. We sequenced its 2.6-Mb GC-rich chromosome and two plasmids (131 and 23 kb). Genome analysis suggests that it is adapted to cope with severe ammonia and heavy metal deficiencies that arise at high pH values. A high degree of nutritional self-sufficiency was predicted and confirmed by growth in a minimal medium containing leucine but no other amino acids or vitamins. Genes for a complex III analog of the respiratory chain could not be identified in the N. pharaonis genome, but respiration and oxidative phosphorylation were experimentally proven. These studies identified protons as coupling ion between respiratory chain and ATP synthase, in contrast to other alkaliphiles using sodium instead. Secretome analysis predicts many extracellular proteins with alkaline-resistant lipid anchors, which are predominantly exported through the twin-arginine pathway. In addition, a variety of glycosylated cell surface proteins probably form a protective complex cell envelope. N. pharaonis is fully equipped with archaeal signal transduction and motility genes. Several receptors/transducers signaling to the flagellar motor display novel domain architectures. Clusters of signal transduction genes are rearranged in haloarchaeal genomes, whereas those involved in information processing or energy metabolism show a highly conserved gene order.
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PMID:Living with two extremes: conclusions from the genome sequence of Natronomonas pharaonis. 1616 24

The salt-mediated-stress response in Rhodobacter sphaeroides f. sp. denitrificans IL 106 was investigated by culturing cells in the presence and in the absence of NaCl in growth media. Fractionation of cells followed by SDS-PAGE and 2D-PAGE revealed an increase in the levels of membrane proteins of 39 and 50 kDa and a decrease in the level of a membrane protein of 52 kDa with increasing levels of external NaCl. The proteins were isolated and sequenced. The polypeptide of 50 kDa in the inner membrane was assigned to an ATP synthase beta chain and that of 52 kDa in the outer membrane to a flagellar filament protein. As the N terminal of the 39 kDa protein in the outer membrane was blocked, partial proteolysis was carried out and four peptides were sequenced. Each sequence exhibited no significant homology with those available in databases, suggesting that the polypeptide of 39 kDa (named SspA) is a novel salt-stress-induced protein.
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PMID:Salt-stress-responsive membrane proteins in Rhodobacter sphaeroides f. sp. denitrificans IL 106. 1623 81

Large areas of northern China have alkaline soil due to the accumulation of sodium carbonates (NaHCO3, Na2CO3). To understand better how plants can tolerate alkaline soil, a cDNA library was prepared from rice (Oryza sativa L.) roots grown in the presence of NaHCO3 stress. A cDNA clone isolated from this library was identified by a homology search as a mitochondrial ATP synthase 6 kDa subunit gene (RMtATP6; GenBank accession nos AB055076, BAB21526). In transformed yeast and tobacco protoplasts, the RMtATP6 protein was localized in mitochondria using the green fluorescent protein (GFP) marker. Analysis of RMtATP6 mRNA levels suggested that the expression of this gene was induced by stress from sodium carbonates and other sodium salts. Transgenic tobacco overexpressing the RMtATP6 gene had greater tolerance to salt stress at the seedling stage than untransformed tobacco. Among the other genes for F1F0-ATPase of rice, some were found to be up-regulated by some environmental stresses and some were not. These data suggest that the RMtATP6 protein acts as a subunit of ATP synthase, and is expressed in response to stress from several salts, with the other genes coding for the subunits of the same ATP-synthase.
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PMID:Identification of a mitochondrial ATP synthase small subunit gene (RMtATP6) expressed in response to salts and osmotic stresses in rice (Oryza sativa L.). 1631 34

The role of ABA in the modification of membrane proton pump activity in cucumber roots which had been stressed for 24h with 200 mmol/dm(3) NaCl was investigated. It was shown that treatment of plants with salt distinctly increased the activity of the plasma membrane H(+)-ATPase (EC 3.6.3.6) as well as of the vacuolar H(+)-ATPase (EC 3.6.3.14). In roots treated with NaCl, an increase of ABA level was observed. Moreover, 24-h treatment of seedlings with 50 micro mol/dm(3) ABA increased the activity of proton pumps in both membranes. However, when ABA was added to the reaction medium, no changes in ATPase activities were observed. The increased H(+)-ATPase activity in plasma membranes isolated from the ABA-treated roots was positively correlated with a higher level of PM-H(+)-ATPase transcript. These data have provided evidence that under salt stress conditions, the role of ABA action due to salinity on the induction of the PM-H(+)-ATPase could be at the level of gene expression.
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PMID:Modification of plasma membrane and vacuolar H+ -ATPases in response to NaCL and ABA. 1654 49

The turnip (Brassica rapa L.) microsome fraction contains both a Mg(2+)-inhibited acid phosphatase and a salt-stimulated Mg(2+)-activated ATPase. However, as the pH optimum of the ATPase was 8.0 to 8.5, the acid phosphatase activity could be eliminated by assaying at or above pH 7.8. The ATPase was concentrated in a fraction equivalent to the smooth microsomal membranes and was not due to fragments of mitochondria. The salt-stimulated activity showed specificity for anions rather than cations. The activity was further stimulated by carbonyl cyanide m-chloro-phenylhydrazone (CCCP), 2,4-dinitrophenol, valinomycin, nigericin, and NH(4)Cl. There was a synergistic effect between CCCP and valinomycin. Activity was insensitive to oligomycin phlorizin, ouabain, and atractylate. Based on similarity to the chloroplast ATPase, it was proposed that this ATPase was situated on the outside of the vesicle.It is suggested that the ATPase is involved in the movement of ions, particularly anions, and may be related to the anion accumulation mechanism, which is known to occur across the tonoplast of such tissues.
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PMID:Salt-stimulated Adenosine Triphosphatase from Smooth Microsomes of Turnip. 1665 66

To understand the function and membrane origin of ionophore-stimulated ATPases, the activity of nigericin-stimulated ATPase was characterized from a low-density microsomal fraction containing sealed vesicles of autonomous tobacco (Nicotiana tabacum Linnaeous cv. Wisconsin no. 38) callus. The properties of KCl-stimulated, Mg-requiring ATPases (KCl-Mg,ATPase) were similar in the absence or presence of nigericin. Nigericin (or gramicidin) stimulation of a KCl-Mg,ATPase activity was optimum at pH 6.5 to 7.0. The enzyme was inhibited completely by N,N'-dicyclohexylcarbodiimide (10 mum), tributyltin (5 mum), and partially by vanadate (200 mum), but it was insensitive to fusicoccin and mitochondrial ATPase inhibitors, such as azide (1 mm) and oligomycin (5 mug/ml). The ATPase was more sensitive to anions than cations. Cations stimulated ATPase activity with a selectivity sequence of NH(4) (+) > K(+), Rb(+), Cs(+), Na(+), Li(+) > Tris(+). Anions stimulated Mg, ATPase activity with a decreasing sequence of Cl(-) = acetate > SO(4) (2-) > benzene sulfonate > NO(3) (-). The anion stimulation was caused partly by dissipation of the electrical potential (interior positive) by permeant anions and partly by a specific ionic effect. Plant membranes had at least two classes of nigericin-stimulated ATPases: one sensitive and one insensitive to vanadate. Many of the properties of the nigericin-sensitive, salt-stimulated Mg,ATPase were similar to a vanadate-sensitive plasma membrane ATPase of plant tissues, yet other properties (anion stimulation and vanadate insensitivity) resembled those of a tonoplast ATPase. These results support the idea that nigericin-stimulated ATPases are mainly electrogenic H(+) pumps originated in part from the plasma membrane and in part from other nonmitochondrial membranes, such as the tonoplast.
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PMID:Characterization of nigericin-stimulated ATPase from sealed microsomal vesicles of tobacco callus. 1666 23

Following a N-methyl-N'-nitro-N-nitrosoguanidine-based mutagenesis of Synechococcus elongatus PCC 7942 wild type, we were able to select several mutants with an enhanced tolerance toward the herbicide bentazone (3-isopropyl-1H-2,1,3-benzothiadiazine-4(3H)-one 2,2-dioxide). Mutant Mu1 has in part been previously characterized. In the present paper we report on another mutant, called Mu2, which also has a higher tolerance toward bentazone. Since Mu2 showed a better growth than WT when cultivated with elevated NaCl concentrations in the growth medium and since S. elongatus WT has previously been classified to be low salt tolerant, we were especially interested in the identification of the modifications conferring this higher salt tolerance to mutant Mu2. Immunoblot analyses provided evidence that Mu2 had a constitutively higher expression of PsbO and of IsiA. In addition, in Mu2 a significantly higher concentration of IdiA was detected under salt stress as compared to WT. These three proteins most likely contribute to a better protection and/or stabilization of photosystem II. Moreover, Mu2 had a higher amount of the photosystem I reaction center proteins PsaAB under salt stress than WT. In addition, the amount of the ferredoxin:NADP+ oxidoreductase and also of the ATP synthase was constitutively higher in Mu2 than in WT. In contrast to WT the latter two proteins did not decrease under salt stress in Mu2. Therefore, it can be assumed that Mu2 could maintain a high cyclic electron transport activity around photosystem I under salt stress. It can be assumed that the combination of these modifications of the electron transport chain cause a better protection of photosystem II against oxidative damage and cause an increase of cyclic electron transport activity around photosystem I with ATP synthesis. Thus, the overall cellular energization in Mu2 relative to WT is improved. Together with putative other not yet identified modifications this seems to enable Mu2 to energize its cytoplasmic membrane-localized ion pumps more effectively than WT and, as a consequence, to keep the intracellular NaCl concentration low.
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PMID:A Synechococcus elongatus PCC 7942 mutant with a higher tolerance toward the herbicide bentazone also confers resistance to sodium chloride stress. 1755 35

The ATP synthase of the thermoalkaliphilic Bacillus sp. TA2.A1 operates exclusively in ATP synthesis direction. In the crystal structure of the nucleotide-free alpha(3)beta(3)gamma epsilon subcomplex (TA2F(1)) at 3.1 A resolution, all three beta subunits adopt the open beta(E) conformation. The structure shows salt bridges between the helix-turn-helix motif of the C-terminal domain of the beta(E) subunit (residues Asp372 and Asp375) and the N-terminal helix of the gamma subunit (residues Arg9 and Arg10). These electrostatic forces pull the gamma shaft out of the rotational center and impede rotation through steric interference with the beta(E) subunit. Replacement of Arg9 and Arg10 with glutamines eliminates the salt bridges and results in an activation of ATP hydrolysis activity, suggesting that these salt bridges prevent the native enzyme from rotating in ATP hydrolysis direction. A similar bending of the gamma shaft as in the TA2F(1) structure was observed by single-particle analysis of the TA2F(1)F(o) holoenzyme.
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PMID:The structural basis for unidirectional rotation of thermoalkaliphilic F1-ATPase. 1769 91

In this work, major protein changes in the albedo of the fruit peel of Murcott tangor (tangerine x sweet orange) during postharvest ageing were studied through 2D PAGE. Protein content in matured on-tree fruits and in fruits stored in nonstressing [99% relative humidity (RH) and 25 degrees C], cold (99% RH and 4 degrees C), and drought (60% RH and 25 degrees C) conditions was initially determined. Protein identification through MS/MS determinations revealed in all samples analyzed the occurrence of manganese superoxide dismutase (Mn SOD), actin, ATP synthase beta subunit (ATPase), citrus salt-stress associated protein (CitSap), ascorbate peroxidase (APX), translationally controlled tumor protein (TCTP), and a cysteine proteinase (CP) of the papain family. The latter protein was identified in two different gel spots, with different molecular mass, suggesting the simultaneous presence of the proteinase precursor and its active form. While Mn SOD, actin, ATPase, and CitSap were unchanged in the assayed conditions, TCTP and APX were downregulated during the postharvest ageing process. Ageing-induced APX repression was also reversed by drought. CP contents in albedo, which were similar in on- and off-tree fruits, were strongly dependent upon cold storage. The active/total CP protein ratio significantly increased after cold exposure. This proteomic survey indicates that major changes in protein content in the albedo of the peel of postharvest stored citrus fruits are apparently related to the activation of programmed cell death (PCD).
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PMID:Protein changes in the albedo of citrus fruits on postharvesting storage. 1791 May 11


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