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)

We report the finding of mitochondrial ATP-synthase deficiency in a child with persistent 3-methylglutaconic aciduria. The child presented in the neonatal period with severe lactic acidosis, which was controlled by Na-HCO3 and glucose infusions. During the 1st y of life, there were several episodes of lactic acidosis precipitated by infections or prolonged intervals between meals. The excretion of lactate in urine was variable, but there was a persistent high excretion of 3-methylglutaconic acid. The activity of 3-methylglutaconyl-CoA hydratase in fibroblasts was normal. The child had a hypertrophic cardiomyopathy and magnetic resonance images revealed hypoplasia of corpus callosum. The gross motor and mental development was retarded, but there were no other neurologic signs. Investigation of muscle mitochondrial function at 1 y of age revealed a severe mitochondrial ATP-synthase deficiency (oligomycin-sensitive, dinitrophenol-stimulated Mg2+ ATPase activity: 27 nmol x min-1 x (mg protein)-1, control range 223-673 nmol x min-1 x (mg protein)-1. The mitochondrial respiratory rate was low and tightly coupled. The respiratory rate was normalized by the addition of an uncoupler. Low Mg2+ ATPase activity was also demonstrated by histochemical methods. Morphologic examination revealed ultrastructural abnormalities of mitochondria. There was no deletion of mitochondrial DNA. The sequences of the ATP synthase subunit genes of mitochondrial DNA were in accordance with published normal sequences.
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PMID:Mitochondrial ATP-synthase deficiency in a child with 3-methylglutaconic aciduria. 128 64

In a patient with a mitochondrial myopathy, presenting with lactic acidosis, 31P-nuclear magnetic resonance spectroscopy in resting muscle showed half the creatine phosphate level of controls. The creatine phosphate resynthesis rate after aerobic exercise was only 18% of that in controls. However, the activities of complexes I to V catalyzing oxidative phosphorylation and the pyruvate and the 2-oxoglutarate dehydrogenase complexes showed a 2- to 20-fold increase. In line with this, the uncoupled mitochondrial respiration rate was significantly higher than in controls. In contrast, the respiration of the mitochondria from the patient was less stimulated by ADP than that of control mitochondria. This finding could point to a defect in complex V, the enzyme directly involved in ATP synthesis. The activity of complex V, measured as the mitochondrial ATPase activity, and its concentration, as judged from Western blots using antisera against the F1 part of complex V, were, however, also greatly increased in the patient. Alternatively, the transport system, importing ADP into and exporting ATP out of the mitochondrial matrix, the ADP/ATP or adenine nucleotide translocator, could be affected. Immunostaining of Western blots revealed a 4-fold decrease in the concentration of the adenine nucleotide translocator in the patient. Because oxidative phosphorylation was not disturbed in fibroblasts and lymphocytes, we conclude that this patient suffers from a muscle-specific deficiency of his mitochondrial adenine nucleotide translocator, a defect unknown so far.
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PMID:Deficiency of the adenine nucleotide translocator in muscle of a patient with myopathy and lactic acidosis: a new mitochondrial defect. 847 24

The transcript levels of nuclear and mitochondrial genes involved in oxidative phosphorylation were quantified in human myoblasts and myotubes cultured from biopsies of patients harboring either heteroplasmic point mutation or deletion of mitochondrial DNA. The transcript patterns were determined by two different methodologies, competitive reverse-transcription polymerase chain reaction and classical Northern blot analysis, both referred to the mitochondrial to nuclear DNA ratio. In myoblasts from the patients with MELAS (myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) and KSS (Kearns-Sayre) syndromes, both methodologies revealed an increase of mtDNA transcript levels. A higher level of the nuclear ATP synthase beta transcript was observed in the MELAS patient cells and could be the consequence of a feedback effect of the mitochondrial DNA mutation. Moreover, the nuclear and mitochondrial transcript accumulation is more pronounced after myoblast differentiation. Thus, the OXPHOS expression is specifically altered in patients with mitochondrial diseases. The competitive RT-PCR, a rapid and sensitive technique, could be applied to investigation of mitochondrial myopathies.
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PMID:Quantification of OXPHOS gene transcripts during muscle cell differentiation in patients with mitochondrial myopathies. 988 18

We have examined the transcript levels of a variety of oxidative phosphorylation (OXPHOS) and associated bioenergetic genes in tissues of a patient carrying the myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) A3243G mitochondrial DNA (mtDNA) mutation and the skeletal muscles of 14 patients harboring other pathogenic mtDNA mutations. The patients' tissues, which harbored 88% or more mutant mtDNA, had increased levels of mtDNA transcripts, increased nuclear OXPHOS gene transcripts including the ATP synthase beta subunit and the heart-muscle isoform of the adenine nucleotide translocator, and increased ancillary gene transcripts including muscle mitochondrial creatine phosphokinase, muscle glycogen phosphorylase, hexokinase I, muscle phosphofructokinase, the E1alpha subunit of pyruvate dehydrogenase, and the ubiquinone oxidoreductase. A similar coordinate induction of bioenergetic genes was observed in the muscle biopsies of severe pathologic mtDNA mutations. The more significant coordinated expression was found in muscle from patients with the MELAS, myoclonic epilepsy with ragged red fibers, and chronic progressive external ophthalmoplegia deletion syndromes, with ragged red muscle fibers and mitochondrial paracrystalline inclusions. High levels of mutant mtDNAs were linked to a high induction of the mtDNA and nuclear OXPHOS genes and of several associated bioenergetic genes. These observations suggest that human tissues attempt to compensate for OXPHOS defects associated with mtDNA mutations by stimulating mitochondrial biogenesis, possibly mediated through redox-sensitive transcription factors.
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PMID:Coordinate induction of energy gene expression in tissues of mitochondrial disease patients. 1043 62

We report a new type of fatal mitochondrial disorder caused by selective deficiency of mitochondrial ATP synthase (ATPase). A hypotrophic newborn from a consanguineous marriage presented severe lactic acidosis, cardiomegaly and hepatomegaly and died from heart failure after 2 days. The activity of oligomycin-sensitive ATPase was only 31-34% of the control, both in muscle and heart, but the activities of cytochrome c oxidase, citrate synthase and pyruvate dehydrogenase were normal. Electrophoretic and western blot analysis revealed selective reduction of ATPase complex but normal levels of the respiratory chain complexes I, III and IV. The same selective deficiency of ATPase was found in cultured skin fibroblasts which showed similar decreases in ATPase content, ATPase hydrolytic activity and level of substrate-dependent ATP synthesis (20-25, 18 and 29-33% of the control, respectively). Pulse-chase labelling of patient fibroblasts revealed low incorporation of [(35)S]methionine into assembled ATPase complexes, but increased incorporation into immunoprecipitated ATPase subunit beta, which had a very short half-life. In contrast, no difference was found in the size and subunit composition of the assembled and newly produced ATPase complex. Transmitochondrial cybrids prepared from enucleated fibroblasts of the patient and rho degrees cells derived from 143B. TK(-)human osteosarcoma cells fully restored the ATPase activity, ATP synthesis and ATPase content, when compared with control cybrids. Likewise, the pattern of [(35)S]methionine labelling of ATPase was found to be normal in patient cybrids. We conclude that the generalized deficiency of mitochondrial ATPase described is of nuclear origin and is caused by altered biosynthesis of the enzyme.
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PMID:A novel deficiency of mitochondrial ATPase of nuclear origin. 1048 64

We report two male Taiwanese siblings in whom the T-->C point mutation at nucleotide 9176 of the mitochondrial ATPase 6 gene (m.9176T>C mutation) was associated with early onset hypotonia, lactic acidosis, and death due to respiratory arrest at 7 and 10 months old. Brain MRI showed lesions over diffuse white matter and the bilateral posterior limbs of the internal capsule. The m.9176T>C mutation is suggested as the cause of the bilateral striatal necrosis and Leigh syndrome. However, leukodystrophy in Leigh syndrome associated with m.9176T>C mutation has never been reported before. We suggest that m.9176T>C mutation could be a new aetiology for leukodystrophy in children with Leigh syndrome.
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PMID:A previously undescribed leukodystrophy in Leigh syndrome associated with T9176C mutation of the mitochondrial ATPase 6 gene. 1720 80

An increasing number of patients with nuclear genetic defects of mitochondrial ATP synthase have been identified in recent years. They are characterized by early onset, lactic acidosis, 3-methylglutaconic aciduria, hypertrophic cardiomyopathy and encephalopathy and most cases have a fatal outcome. Patient tissues show isolated defect of the ATP synthase complex and its content decreases to > or =30% of normal due to altered enzyme biosynthesis and assembly. Gene mapping and complementation studies have identified mutations in TMEM70 gene encoding a 30kD mitochondrial protein of unknown function as the cause of the disease. An altered synthesis of this new ancillary factor in ATP synthase biogenesis was found in most of the known patients with decreased ATP synthase content. As revealed by phylogenetic analysis, TMEM70 is specific for higher eukaryotes.
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PMID:TMEM70 protein - a novel ancillary factor of mammalian ATP synthase. 1910 53

We describe the characterization of polyclonal antibodies directed against the whole mitochondrial subproteome, as obtained by hyperimmunization of rabbits with an organelle fraction purified from human skeletal muscle and lysed by sonication. After 2-DE separations with either blue native electrophoresis or IPG as first dimension and blotting, the polyspecific antibodies detect 113 proteins in human muscle mitochondria, representative of all major biochemical pathways and oxidative phosphorylation (OXPHOS) complexes, and cross-react with 28 proteins in rat heart mitochondria. Using as sample cryosections of human muscle biopsies lysed in urea/thiourea/CHAPS, the mitochondrial subproteome can be detected against the background of contractile proteins. When comparing with controls samples from mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes patients, immunoblotting shows in the latter a drastic reduction for the subunits of OXPHOS complex I as well as an increase of several enzymes, including ATP synthase. This finding is the first evidence at the proteomic level of massive up-regulation in a number of metabolic pathways by which the affected tissues try to compensate for the deficit in the OXPHOS machinery.
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PMID:Development and characterization of polyspecific anti-mitochondrion antibodies for proteomics studies on in toto tissue homogenates. 1938 33

F1Fo-ATP synthase is a key enzyme of mitochondrial energy provision producing most of cellular ATP. So far, mitochondrial diseases caused by isolated disorders of the ATP synthase have been shown to result from mutations in mtDNA genes for the subunits ATP6 and ATP8 or in nuclear genes encoding the biogenesis factors TMEM70 and ATPAF2. Here, we describe a patient with a homozygous p.Tyr12Cys mutation in the epsilon subunit encoded by the nuclear gene ATP5E. The 22-year-old woman presented with neonatal onset, lactic acidosis, 3-methylglutaconic aciduria, mild mental retardation and developed peripheral neuropathy. Patient fibroblasts showed 60-70% decrease in both oligomycin-sensitive ATPase activity and mitochondrial ATP synthesis. The mitochondrial content of the ATP synthase complex was equally reduced, but its size was normal and it contained the mutated epsilon subunit. A similar reduction was found in all investigated F1 and Fo subunits with the exception of Fo subunit c, which was found to accumulate in a detergent-insoluble form. This is the first case of a mitochondrial disease due to a mutation in a nuclear encoded structural subunit of the ATP synthase. Our results indicate an essential role of the epsilon subunit in the biosynthesis and assembly of the F1 part of the ATP synthase. Furthermore, the epsilon subunit seems to be involved in the incorporation of subunit c to the rotor structure of the mammalian enzyme.
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PMID:Mitochondrial ATP synthase deficiency due to a mutation in the ATP5E gene for the F1 epsilon subunit. 2056 10

Mitochondrial disorders are a large and genetically heterogeneous group of disorders posing a significant diagnostic challenge. Only approximately 10-20% of patients have identifiable alterations in their mitochondrial DNA (mtDNA). The remaining ~80-90% of affected patients likely harbor mutations in nuclear genes, most of which are still poorly characterized, and therefore not amenable to efficient screening using currently available molecular methods. Here we present a patient, who has been followed since birth after presenting with neonatal hyperammonemia, lactic acidosis, Reye-like syndrome episodes, and ventricular tachyarrhythmia. Initial biochemical work-up revealed hyperalaninemia, normal plasma glutamine, mild orotic aciduria and significant amounts of urinary 3-methylglutaconic (3-MGC) and 3-methylglutaric (3-MGA) acids. Muscle biopsy demonstrated the presence of ragged-red fibers and non-specific structural abnormalities of mitochondria. The activities of respiratory chain enzymes (complexes I-IV) showed no deficiency. Mutational analysis of the entire mitochondrial genome did not reveal deleterious point mutations or large deletions. Long-term follow-up was significant for a later-onset hypertrophic cardiomyopathy, muscle weakness, and exercise intolerance. Although she had frequent episodes of Reye-like episodes in infancy and early childhood, mostly triggered by illnesses, these symptoms improved significantly with the onset of puberty. In the light of recent reports linking cases of type IV 3-methylglutaconic aciduria (3-MGCA) and hypertrophic cardiomyopathy to mutations in TMEM70, we proceeded with sequencing analysis of this gene. We identified one previously reported splice site mutation, c.317-2A>G and a novel mutation c.494G>A (p.G165D) in an evolutionarily conserved region predicted to be deleterious. This variant was not identified in 100 chromosomes of healthy control subjects and 200 chromosomes of patients with cardiomyopathies. Western blotting using a polyclonal antibody against ATP5J, subunit F6 of ATP synthase, on patient's skin fibroblasts showed undetectable amount of the ATP5J protein. In comparison to the previously reported cases, we note that our patient had normal growth parameters and cognitive development, absence of structural heart and urinary tract defects, no dysmorphic features, improvement of symptoms with age, and persistence of hypertrophic cardiomyopathy.
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PMID:Milder clinical course of Type IV 3-methylglutaconic aciduria due to a novel mutation in TMEM70. 2072 87


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