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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)

The effect of the association of Gossypol and Lonidamine on the energy metabolism of Ehrlich ascites tumor cells has been investigated. The action of the drug on tumor cells was studied by addition of the drugs to cells harvested from Swiss male mice. The results may be summarized as follows: (1) Low concentrations of Gossypol increase the rate of oxygen consumption by uncoupling oxidative phosphorylation. High concentrations result in an inhibition of oxygen consumption with a mechanism that must be regarded as not directly related to the uncoupling activity. (2) Gossypol, at concentrations at which it exerts an uncoupling activity, stimulates mitochondrial ATPase which in turn increases the aerobic and anaerobic rates of lactate production. The decrease of glycolysis at high concentrations of Gossypol does not depend on the inhibition of enzymes of the glycolytic pathway, but must be ascribed to cell death. (3) The association of a low concentration of Gossypol with Lonidamine brings about a further inhibition of oxygen consumption. Moreover, Lonidamine abolishes the stimulation of glycolysis induced by Gossypol and lowers lactate production to values that are quite similar to those found with Lonidamine alone. (4) It may be concluded that the association of Gossypol and Lonidamine results in a very effective decrease of the energy requirements of cancer cells.
Exp Mol Pathol 1983 Jun
PMID:The effect of the association of Gossypol and Lonidamine on the energy metabolism of Ehrlich ascites tumor cells. 685 6

A simple molecular dynamics (MD) simulations is protocol shown to predict whether a residue is in a structured alpha-helical segment or in a mobile loop or terminal segment of a membrane protein. The results are verified by comparisons with experimental NMR data. The protocol consists of performing several independent MD simulations on a polypeptide sequence of interest in a dielectric continuum with a relative permittivity epsilon = 2. The time histories of the individual angles between NH bond vectors at time 0 and time t later are calculated, and then Gaussian smoothing of typically 50 ps is applied. The smoothed data are subtracted from the original data to yield the short time fluctuations of the NH bond vectors, and then the rms deviations of the angles are calculated and compared to experimental NMR results. Pf1 coat protein and the c subunit of the E. coli F1F0 ATP synthase are used as examples of membrane proteins. The calculated NH bond rms fluctuations are in qualitative agreement with experimental NMR data in showing that each of these proteins has a mobile segment connecting two helices, as well as mobile N and C-terminal regions. This MD simulations protocol can demonstrate the presence of both the amphipathic and hydrophobic helices while hydropathy plots are able to detect only the hydrophobic helices present in membrane proteins.
J Mol Biol 1995 Oct 27
PMID:A simple protocol for identification of helical and mobile residues in membrane proteins. 747 22

Ischemic preconditioning of the heart is referred as a manifest increase in tolerance of the myocardium to otherwise damaging ischemic insult, achieved by one or few consequent initial short exposures to ischemia, each followed by reperfusion of the ischemic area. Several mechanisms such as opening of collateral vessels, the action of catecholamines, inositol phosphates, G-proteins and/or adenosine; inhibition of mitochondrial ATPase, the effects of different endogenous protective substances like heat stress or shock proteins, etc., are believed to cooperate in the mechanism of induction of preconditioning or in maintaining its effect. The present study is an attempt to extend the present knowledge about preconditioning from two aspects: i.) the peculiarities of energy equilibrium in preconditioned myocardium including adaptation of cardiac sarcolemmal ATPases to ischemia and/or hypoxia, and ii) participation of a new endogenous cardioprotective substance in the mechanism of preconditioning. The energy equilibrium in preconditioning is characterized by adaptation of cardiac energy demands to the capacity of energy production and delivery decreased by anaerobiosis and is manifested by constant ratios between ATP, ADP, AMP and the sum of ADN. Principles are proposed that may enable a prediction and mathematical modelling of the balanced energetic state in the preconditioned myocardium. These principles are based on thermodynamics and involve besides others a more economic handling of ATP by sarcolemmal ATPases. The latter enzymes adapt themselves to lowered availability of ATP by decreasing besides their Vmax also their values of Km (increase in the affinity) for ATP and some of them even adjust their activation energy (the anaerobiosis-induced elevation of Ea.t. is missing).(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem
PMID:Adaptation of the heart to ischemia by preconditioning: effects on energy equilibrium, properties of sarcolemmal ATPases and release of cardioprotective proteins. 749 41

Transcription termination factor rho from Escherichia coli is a homohexamer of 419 amino acid subunits and catalyzes an ATP-dependent release of nascent RNA transcripts. A rho monomer has three distinct domains functioning independently at the first approximation: the amino-terminal one quarter containing a primary RNA-binding site, the central 270-amino acids region constituting an ATP-binding domain with homologies to F1-ATPase, and the carboxy-terminal remainder with unknown function(s). To further delineate the structural and functional organizations of rho protein, we undertook its random mutagenesis using error-prone polymerase chain reactions with the carboxy-terminal 100-amino acid region chosen as the initial target. From 14 mutants identified, rho protein was purified and characterized in vitro. Of these, 11 mutants are defective in termination in vivo and show decreased activities in various partial functions examined: ATP binding; RNA binding; and ATPase activities dependent on three cofactors with decreasing efficacies, poly(C), lambda cro RNA and poly(U). A few of them are also affected in the putative secondary RNA-binding site that is functionally coupled to ATP hydrolysis. By contrast, the three other mutants are hyperactive in termination, poly(U)-dependent ATPase activity, and RNA interaction at the primary site. In these properties, the hyper-terminating mutants strikingly resemble the "super rho" mutant formerly found in the amino-terminal domain. Taken together, these findings indicate that the carboxy-terminal region plays a pivotal role in functionally coupling the RNA and ATP-binding domains, plausibly by acting as an interface for their interaction within or across individual subunits. In light of the reported X-ray crystallographic structure of F1-ATPase, we propose a model for the tertiary and quaternary structure of rho that is consistent with the observed mutational effects as well as a number of structural and functional properties characteristic of rho.
J Mol Biol 1995 Dec 15
PMID:Structural and functional dissections of transcription termination factor rho by random mutagenesis. 750 Mar 53

Respiratory-competent nuclear mutants have been isolated which presented a cryosensitive phenotype on a non-fermentable carbon source, due to a dysfunction of the mitochondrial F1-Fo ATP synthase. This defect results from an alteration of the mtDNA-encoded protein synthesis level of subunits 6 and 8 of the Fo sector, due to the simultaneous presence of a mutation in two unlinked nuclear genes. These mutations promote a modification of the expression of the cotranscript ATP8-ATP6 (formerly denoted AAP1-OL12): this mRNA undergoes a maturation at a unique site reaching to two cotranscripts of 5.2 and 4.6 kb in length: in the mutant, the relative amount of 5.2 kb cotranscript was greatly lowered. NCA2 was isolated from a wild-type yeast genomic library by genetic complementation. The relative level of the 5.2 kb transcript, as the synthesis of subunits 6 and 8, was partly restored in the transformed strain. A 1848 nucleotide open reading frame was depicted that encoded an amphiphilic protein of 70,816 Da. Disruption of chromosomal DNA within the reading frame promoted a dramatic decrease of the 5.2 kb mRNA but did not abolish the respiratory competence of a wild-type strain. Hybridization analyses indicated that NCA2 is located on chromosome XVI and produces a single 2750 base transcript.
J Mol Biol 1995 Apr 07
PMID:NCA2, a second nuclear gene required for the control of mitochondrial synthesis of subunits 6 and 8 of ATP synthase in Saccharomyces cerevisiae. 772 16

OSCP is a subunit of the FA stalk sector of yeast mitochondrial ATP synthase complex. Cells of a null mutant for OSCP, constructed by disruption of the chromosomal ATP5 gene of Saccharomyces cerevisiae, exhibited a high level of genetic instability (petite formation). Study of the effects of ablation of OSCP required the development of a progressive depletion strategy. Introduction of a vector bearing an ATP5 gene cassette under GAL1 transcriptional control into null mutant cells gave rise to a stable yeast strain from which OSCP could be depleted in a controlled manner by manipulation of the level of galactose in the growth medium. Cells progressively depleted of OSCP exhibited properties of cellular respiration indicative of a decline in the functional coupling of the catalytic F1 sector to the proton channel F0 sector (normally linked by FA). Cells depleted of OSCP also exhibited a physical uncoupling of F1 from other subunits of the complex such that other FA subunits and F0 subunit 6 were not recovered in immunoprecipitates of ATP synthase complexes. Thus, OSCP plays a role in the assembly as well as function of the enzyme complex.
Biochem Mol Biol Int 1994 Oct
PMID:Properties of yeast cells depleted of the OSCP subunit of mitochondrial ATP synthase by regulated expression of the ATP5 gene. 786 6

Steady-state mRNA levels for thylakoid proteins were analysed in spinach cotyledons under diurnally changing light conditions. Most fluctuate considerably throughout the day, while the levels of others show only low amplitude or no oscillation. Levels of mRNAs coding for proteins that belong to the same multiprotein complex generally oscillate in parallel and exhibit maxima that are specific for that complex: mRNAs for photosystem I proteins appear prior to those for photosystem II polypeptides and these again prior to mRNAs for the three polypeptides constituting the oxygen-evolving complex. For the mRNAs that change with high amplitudes (e.g. those for LHCP or the 20 kDa apoprotein of the CP24 complex) oscillations have also been found under constant conditions, indicating that a circadian oscillator is involved. Transgenic tobacco seedlings harbouring chimeric GUS gene fusions with 5'-flanking sequences from the spinach genes Lhcb, PsaF and AtpD (encoding a light-harvesting chlorophyll a/b apoprotein of photosystem II, subunit 3 of photosystem I and subunit delta of the plastid ATP synthase, respectively) confirm that the differences in the amplitudes as well as the timepoints of maximum mRNA accumulation are perceived via cis-regulatory elements upstream of the respective ATG codons.
Mol Gen Genet 1995 Feb 20
PMID:The steady-state mRNA levels for thylakoid proteins exhibit coordinate diurnal regulation. 789 61

Four subunits of the F1F0-ATPase from bovine heart mitochondria have been produced by heterologous over-expression in Escherichia coli. They are the oligomycin sensitivity conferral protein (OSCP), coupling factor 6 (F6) and subunits b and d. Likewise, fragments b', bI, bC, and bM (amino acid residues 79 to 214, 121 to 214, 165 to 214 and 79 to 164, respectively, of subunit b), and fragment d' (subunit d lacking residue 1 to 14) have been produced in abundant quantities by bacterial expression. These subunits, and the fragments of subunits b and d, have been assayed singly and in various combinations by gel-filtration chromatography for their abilities to bind to bovine heart F1-ATPase. Only the OSCP was found to be capable of forming a stable binary complex with F1-ATPase. When fragments b', bI or bC were added to F1-ATPase together with the OSCP, the ternary complexes F1.OSCP.b', F1.OSCP.bI or F1.OSCP.bC were formed, but b', bI and bC appeared to be present in sub-stoichiometric amounts. When F6 was added also, then the stoichiometric quaternary complexes F1.OSCP.b'.F6 and F1.OSCP.bI.F6 were obtained, as was a fourth quaternary complex containing approximately equivalent amounts of F1 and OSCP, and sub-stoichiometric quantities of bC and F6. Finally, three pentameric complexes F1.OSCP.b'.F6.d, F1.OSCP.b'.F6.d' and F1.OSCP.b.F6.d were isolated. In a further series of reconstitution experiments, the binary complexes b'.OSCP and b'.d, the ternary complex b'.d'.F6, and the quaternary complex OSCP.b'.F6.d were obtained. The pre-formed quaternary complex produced a stoichiometric pentameric complex with F1-ATPase. It was shown by S-carboxymethylation of cysteine residues with iodo-[2-14C]acetic acid that bovine F1F0-ATPase and the reconstituted F1.stalk complex, F1.OSCP.b'.d.F6, each contained one copy per complex of subunits b (or b'), OSCP and d, and that the separate stalk complex contained the same three subunits in the approximate molar ratio 1:1:1. The ratio of b to d in purified F0 was 1:1. Finally, it was demonstrated that the binding of the various subunits to F1-ATPase increases the ATP hydrolase activity and diminishes its inactivation by exposure to cold. These assembly experiments help to define some of the inter-subunit interactions in the stalk region of the F1F0-ATPase complex, and they are an essential step forward towards the goal of extending the high-resolution structure of bovine F1-ATPase into the stalk.
J Mol Biol 1994 Sep 30
PMID:ATP synthase from bovine heart mitochondria. In vitro assembly of a stalk complex in the presence of F1-ATPase and in its absence. 793

The mutant beta subunit of F1-ATPase from a thermophilic Bacillus strain, PS3, in which tyrosine at position 341 is replaced by leucine (beta Y341L) was expressed in Escherichia coli and crystallized by the vapor-diffusion procedure. Small needle-like crystals were obtained using ammonium sulfate as a precipitant and grown by the stepwise seeding method. The crystals obtained by this procedure diffracted X-rays to about 3 A resolution. The diffraction patterns indicated that the crystals belong to the orthorhombic system and the space group I222 or I2(1)2(1)2(1) with unit-cell dimensions of a = 232 A, b = 66 A, and c = 80 A. It is thought that the asymmetric unit comprises one beta Y341L molecule.
J Mol Biol 1994 Oct 07
PMID:Crystallization of mutant beta subunit of F1-ATPase from thermophilic Bacillus PS3. 793 28

In this study we report the first comparison of the mitochondrial protein import and processing events in two different tissues from the same organism. Both spinach leaf and root mitochondria were able to import and process the in vitro transcribed and translated Neurospora crassa F1 beta subunit of ATP synthase to the mature size product. Temperature optimum for protein import, 20 degrees C, was considerably lower than that found in other systems. In spinach leaf mitochondria, the processing peptidase has been shown to constitute an integral part of the bc1 complex of the respiratory chain. In accordance with these results, the majority of the processing activity in root mitochondria was also localized in the membrane. However, although the same amount of the processing peptidase was present per mg of membrane protein in both leaf and root mitochondria, as determined immunologically, the specific processing activity was several-fold higher in roots. Furthermore, in contrast to the processing enzyme in leaf, a portion of the processing activity could be disassociated from the root membrane with relatively weak salt treatment. The processing event in both the leaf and root membranes was always accompanied by a degradation of the F1 beta precursor. The degradation activity was found to be several-fold higher in roots than in leaves and was also partially dissociated from the membrane after salt treatment. Both the processing and degradation activities were inhibited by orthophenanthroline, a known metalloprotease inhibitor. These results show tissue-specific differences of the processing event catalyzed by the bc1 complex and indicate the presence of two populations of the processing peptidase in root mitochondria.
Plant Mol Biol 1994 Oct
PMID:Tissue-specific differences of the mitochondrial protein import machinery: in vitro import, processing and degradation of the pre-F1 beta subunit of the ATP synthase in spinach leaf and root mitochondria. 794 13


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