Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to assess the role of thiol groups in the Fo part of the ATP synthase in the coupling mechanism of ATP synthase, we have treated isolated Fo, extracted from beef heart Complex V with urea, with thiol reagents, primarily with diazenedicarboxylic acid bis-(dimethylamide) (diamide) but also with Cd2+ and N-ethylmaleimide. FoF1 ATP synthase was reconstituted by adding isolated F1 and the oligomycin-sensitivity-conferring-protein (OSCP) to Fo. The efficiency of reconstitution was assessed by determining the sensitivity to oligomycin of the ATP hydrolytic activity of the reconstituted enzyme. Contrary to Cd2+, incubation of diamide with Fo, before the addition of F1 and OSCP, induced a severe loss of oligomycin sensitivity, due to an inhibited binding of F1 to Fo. This effect was reversed by dithiothreitol. Conversely, if F1 and OSCP were added to Fo before diamide, no effect could be detected. These results show that F1 (and/or OSCP) protects Fo thiols from diamide and are substantiated by the finding that the oligomycin sensitivity of ATP hydrolysis activity of isolated Complex V was also unaltered by diamide. Gel electrophoresis of FoF1 ATP synthase, reconstituted with diamide-treated Fo, revealed that the loss of oligomycin sensitivity was directly correlated with diminution of band Fo 1 (or subunit b). Concomitantly a band appeared of approximately twice the molecular weight of subunit Fo 1. As this protein contains only 1 cysteine residue (Walker, J. E., Runswick, M. J., and Poulter, L. (1987) J. Mol. Biol. 197, 89-100), the effect of diamide is attributed to the formation of a disulfide bridge between two of these subunits. These results offer further evidence for the proposal, based on aminoacid sequence and structural analysis, that subunit Fo 1 of mammalian Fo is involved in the binding with F1 (Walker et al. (1987]. N-Ethylmaleimide affects oligomycin sensitivity to a lesser extent than diamide, suggesting that the mode of action of these reagents (and the structural changes induced in Fo) is different.
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PMID:ATP synthase complex from beef heart mitochondria. Role of the thiol group of the 25-kDa subunit of Fo in the coupling mechanism between Fo and F1. 290 33

The antipsychotic drug trifluoperazine has been long considered a calmodulin inhibitor from in vitro studies but may function in vivo as a more general inhibitor by disturbing ion fluxes and altering the membrane potential. Resistance to trifluoperazine can arise in Saccharomyces cerevisiae cells by alterations in at least three distinct genetic loci. One locus, defined by a spontaneous dominant trifluoperazine resistance mutation (TFP1-408), was isolated and sequenced. The sequence of the TFP1-408 gene revealed a large open reading frame coding for a large protein of 1,031 amino acids with predicted hydrophobic transmembrane domains. A search of existing amino acid sequences revealed a significant homology with F0F1 ATP synthase. Mutant TFP1-408 cells did not grow efficiently in the presence of 50 mM CaCl2, whereas wild-type cells did. Wild-type cells became resistant to trifluoperazine in the presence of 50 mM CaCl2 or 50 mM MgCl2. Mutant cells showed a higher rate of calcium transport relative to wild-type cells. These data suggest that the TFP1 gene product codes for a transmembrane ATPase-like enzyme possibly involved in Ca2+ transport or in generating a transmembrane ion gradient between two cellular compartments.
Mol Cell Biol 1988 Aug
PMID:A dominant trifluoperazine resistance gene from Saccharomyces cerevisiae has homology with F0F1 ATP synthase and confers calcium-sensitive growth. 290 23

The effect of hyperthermia (1 hr, 41 degrees C) on the functional properties of Ehrlich ascites tumor mitochondria was investigated. Mitochondria isolated from Ehrlich ascites tumor after exposure of whole cells to 41 degrees C for 1 hr still phosphorylate and maintain a normal acceptor control ratio (ACR). The temperature decreases state 4 and ADP-and FCCP-stimulated respiration on various substrates entering at three energy-conserving sites of the respiratory chain. The inhibition of oxygen consumption by NAD- and FAD-linked substrates was 40% for state 4 and 70% for ADP- or FCCP-stimulated respiration. State 4 and FCCP-stimulated respiration of mitochondria on TMPD + ascorbate was affected 38% and 45%, respectively. ATPase activity was unaffected by hyperthermia, indicating that under these experimental conditions, the inhibition of ADP-stimulated respiration does not depend on an effect on either Fo F1-ATPase or adenine translocase, the activity of which is required for ATP entry prior to ATPase activity. Because of the inability to detect a specific site of action of temperature, it is conceivable that hyperthermia might inhibit substrate oxidation by altering some components of the inner mitochondrial membrane, which regulates the kinetic properties of the membrane-associated enzymes.
Exp Mol Pathol 1987 Jun
PMID:Effect of hyperthermia on electron transport in Ehrlich ascites tumor mitochondria. 295 47

At the heat shock temperature of 45 degrees C, there is a transient induction of the synthesis of heat shock proteins and repression of normal protein synthesis in cells of Neurospora crassa. Both conidiospores and mycelial cells resume normal protein synthesis after 60 min at high temperature. At the RNA level, however, these two developmental stages responded with different kinetics to elevated temperature. Heat shock RNAs (for hsp30 and hsp83) accumulated and declined more rapidly in spores than in mycelia, and during recovery spores accumulated mRNA that encoded a normal protein (the proteolipid subunit of the mitochondrial ATPase), whereas mycelia showed no increase in this normal RNA (for at least 120 min). Therefore, the resumption of normal protein synthesis in spores may depend upon accumulation of new mRNAs. In contrast, mycelial cells appeared to change their translational preference during continued incubation at elevated temperature, from a discrimination against normal mRNAs to a resumption of their translation into normal cellular proteins, exemplified by the ATPase proteolipid subunit whose synthesis was measured in the heat-shocked cells.
Mol Cell Biol 1987 Sep
PMID:Two developmental stages of Neurospora crassa utilize similar mechanisms for responding to heat shock but contrasting mechanisms for recovery. 295 57

Twenty minutes of ischemia in canine cardiac muscle produced a 50% to 60% inhibition of the mitochondrial ATPase. The inhibition has been shown to be triggered by a drop in cell pH under the non-energizing conditions which prevail in ischemic cells (Rouslin, W J Biol Chem 258, 9657-9661 (1983). In the present study we showed that the ATPase inhibition produced in situ in ischemic cardiac muscle was preserved in submitochondrial particles (SMP) prepared from mitochondria isolated from the ischemic tissue. The ischemic SMP ATPase was 45 +/- 3% as active as that of control particles. Measurements of the amounts of ATPase inhibitor protein of Pullman and Monroy present in extracts of control and ischemic SMP by two independent methods, titration of rat heart SMP ATPase and radioimmunoassay, revealed that control SMP contained 62 +/- 4% as much inhibitor as ischemic SMP as estimated by the titration procedure and 66 +/- 3% as much as estimated by the RIA. The results suggest that about one-third of the inhibitor was displaced from the control SMP. Finally, submitochondrial particles prepared from 20 min ischemic heart muscle showed a 2.5-fold increase in ATPase specific activity and a concomitant release of 35% of their inhibitor as a result of subsequent reenergization in vitro. Carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) prevented both ATPase reactivation and inhibitor release. These findings support the hypothesis that the observed in situ ATPase inhibition is inhibitor protein mediated. Moreover, they suggest a pathophysiological function for the inhibitor protein in cardiac muscle.
J Mol Cell Cardiol 1987 Jul
PMID:Protonic inhibition of the mitochondrial adenosine 5'-triphosphatase in ischemic cardiac muscle. Reversible binding of the ATPase inhibitor protein to the mitochondrial ATPase during ischemia. 296 Aug 23

Using an antiserum generated against a synthetic peptide predicted from the DNA sequence of the ATPase 6 gene of the mitochondrial DNA, we demonstrate that mitochondria from two oligomycin-resistant Chinese hamster ovary cell lines with a defined mutation in the ATPase 6 gene synthesize an altered ATPase 6 gene product. This altered gene product migrates in sodium dodecyl sulfate-polyacrylamide gels as if it has a molecular mass that is larger by 1000 daltons than the wild-type ATPase 6 gene product. We also demonstrate that mitochondria from four other independently isolated oligomycin-resistant Chinese hamster ovary mutant cell lines contain a similar altered ATPase 6 gene product. These results suggest that all six oligomycin-resistant cell lines have a similar mutation in the ATPase 6 gene of the mitochondrial DNA that encodes subunit 6 of the ATP synthase complex.
Somat Cell Mol Genet 1987 Jul
PMID:Altered form of subunit 6 of mitochondrial ATP synthase complex in oligomycin-resistant mutants of Chinese hamster ovary cells. 297 Jun 80

The (uninhibited) mitochondrial ATPase comprises approximately 90% of the total ATP hydrolyzing activity present in quiescent, ischemic canine heart muscle and its inhibition by its natural inhibitor protein plays a pivotal role in the slowing of tissue ATP depletion during ischemia. While dog heart mitochondria contain a full complement of mitochondrial ATPase inhibitor capable of fully down-regulating the enzyme activity present in this species, rat heart mitochondria contain a much lower level of inhibitor, sufficient to inhibit the enzyme activity present in this species by only approximately 20%. Moreover, this fractional complement of inhibitor remains largely inoperative in the ischemic rat heart. As shown in the present study, one apparent result of the lack of a functional complement of mitochondrial ATPase inhibitor in the rat heart is a more rapid rate of cell ATP depletion during zero-flow ischemia. This in turn results in a more rapidly developed and initially more severe cell acidosis in the ischemic rat heart because ATP hydrolysis produces protons. Finally, and consistent with earlier studies by us, the more rapid ATP depletion together with the more severe acidosis appears to result in a marked increase in the rate of loss of mitochondrial respiratory function in the ischemic rat heart compared to the ischemic dog heart. Our findings suggest that slow heart-rate hearts which contain in situ functional mitochondrial ATPase inhibitor, possess an effective mechanism for sparing cell ATP stores during early ischemia, whereas fast heart-rate hearts which lack in situ mitochondrial ATPase inhibitor function, possess a less effective ATP sparing mechanism.
J Mol Cell Cardiol 1988 Nov
PMID:Factors affecting the loss of mitochondrial function during zero-flow ischemia (autolysis) in slow and fast heart-rate hearts. 297 46

An allele (oliC31) of the A. nidulans oliC gene has been cloned using homology with the equivalent gene from N. crassa. OliC31 codes for an oligomycin-resistant, triethyltin-hypersensitive form of subunit 9 of the mitochondrial ATP synthase complex. Direct selection for oligomycin-resistance was possible following transformation of A. nidulans with the oliC31 gene. The phenotypes of transformants cultured in the presence of oligomycin were indicative of the position of integration of the transforming plasmid within the genome. Subsequent recombination events involving the integrated oliC31 gene were also apparent from altered levels of resistance to oligomycin or triethyltin. This gene should prove useful as a marker for transformation of strains lacking auxotrophic lesions and in gene replacement or disruption experiments.
Mol Gen Genet 1986 Feb
PMID:Transformation of Aspergillus nidulans with a cloned, oligomycin-resistant ATP synthase subunit 9 gene. 301 49

The nucleotide sequence has been determined of two regions of DNA cloned from the cyanobacterium Synechococcus 6301. The larger, 8890 base-pairs in length, contains a cluster of seven genes for subunits of ATP synthase. The order of the genes is a:c:b':b:delta:alpha:gamma, b' being a duplicated and diverged form of b. As in the Escherichia coli unc operon, the a gene is preceded by a gene for a small hydrophobic and basic protein. The hydrophobic profile of the potential gene product suggests that its secondary structure is similar to the uncI protein. The smaller DNA fragment, 4737 base-pairs in length, is separated from the larger by at least 15 X 10(3) base-pairs of DNA. It contains a cluster of two genes encoding ATP synthase subunits beta and epsilon. Both clusters of ATP synthase genes are preceded by sequences resembling the -10 (Pribnow) box of E. coli promoters and are followed by sequences able to form stable stem-loop structures that might serve to terminate transcription. These features and the small intergenic non-coding sequences suggest that the clusters are operons, for which the names atp1 and atp2 are proposed. The order of genes within the two clusters is very similar to the gene order in the E. coli unc operon. However, it is most closely related to the arrangement of genes for ATP synthetase subunits a:c:b:alpha and beta:epsilon in two clusters in pea chloroplast DNA. This close relationship between chloroplasts and the cyanobacterium is also evident from comparisons of the sequences of ATP synthase subunits; the Synechococcus proteins are much more closely related to chloroplast homologues than to those in other bacteria or in mitochondria. It is further supported by the cyanobacterial b and b' proteins which, in common with their chloroplast counterpart, subunit I, have extra amino-terminal extensions relative to the E. coli b protein. This extension is known to be removed by post-translational processing in the chloroplast, but its function is obscure. It also seems likely that the cyanobacterial and chloroplast ATP synthases have important similarities in subunit composition. For example, the presence of two related genes, b and b', in the cyanobacterium suggests that its ATP synthase is a complex of nine polypeptides, and that it may have single copies of related b and b' proteins rather than two copies of identical b subunits as found in the E. coli enzyme.4+off
J Mol Biol 1987 Apr 05
PMID:The organization and sequence of the genes for ATP synthase subunits in the cyanobacterium Synechococcus 6301. Support for an endosymbiotic origin of chloroplasts. 304 Oct 5

Control of mitochondrial respiration depends on ADP availability to the F1-ATPase. An electrochemical gradient of ADP and ATP across the mitochondrial inner membrane is maintained by the adenine nucleotide translocase which provides ADP to the matrix for ATP synthesis and ATP for energy-dependent processes in the cytosol. Mitochondrial respiration is responsive to the cytosolic phosphorylation potential, ATP/ADP.Pi which is in apparent equilibrium with the first two sites in the electron transport chain. Conventional measures of free adenine nucleotides is a confounding issue in determining cytosolic and mitochondrial phosphorylation potentials. The advent of phosphorus-31 nuclear magnetic resonance (P-31 NMR) allows the determination of intracellular free concentrations of ATP, creatine-P and Pi in perfused muscle in situ. In the glucose-perfused heart, there is an absence of correlation between the cytosolic phosphorylation potential as determined by P-31 NMR and cardiac oxygen consumption over a range of work loads. These data suggest that contractile work leads to increased generation of mitochondrial NADH so that ATP production keeps pace with myosin ATPase activity. The mechanism of increased ATP synthesis is referred to as 'stimulus-response-metabolism' coupling. In muscle, increased contractility is a result of interventions which increase cytosolic free Ca2+ concentrations. The Ca2+ signal thus generated increases glycogen breakdown and myosin ATPase in the cytosol. This signal is concomitantly transmitted to the mitochondria which respond to small increases in matrix Ca2+ by activation of Ca2+-sensitive dehydrogenases. The Ca2+-activated dehydrogenase activities are key rate-controlling enzymes in tricarboxylic acid cycle flux, and their activation by Ca2+ leads to increased pyridine nucleotide reduction and oxidative phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1988 Jun
PMID:Control of mitochondrial respiration in muscle. 305 Apr 50


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