Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gene of the soluble fumarate reductase (FRDS) that binds FAD non-covalently was cloned by polymerase chain reaction (PCR) using degenerate oligonucleotides designed from partial amino acid sequences of highly purified enzyme. The nucleotide sequence of a 0.99-kb amplified product was found to be nearly identical to a partial sequence of an open reading frame (ORF) previously reported (EMBL database accession number S-30830). According to the sequence in the EMBL database, we cloned 1.7-kb fragment containing entire sequence of this ORF by PCR and found that this fragment contained a perfect match to the 0.99-kb sequence amplified with the degenerate primers. From these results, we concluded that this ORF is the FRDS gene. The amino acid sequences of the regions involved in the non-covalent binding of FAD and the active site, which are conserved among the flavoprotein subunits of membrane-bound fumarate reductase and succinate dehydrogenase, were found in FRDS. However, unlike the membrane-bound enzymes, FRDS did not contain the histidine residue that covalently binds the isoalloxazine ring of FAD at or near the corresponding position. FRDS showed high homology to the product of S. cerevisiae OSM1 gene which was reported to be required for growth in hypertonic media.
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PMID:Cloning and sequencing of the gene encoding the soluble fumarate reductase from Saccharomyces cerevisiae. 894 66

Defects of the mitochondrial respiratory chain are increasingly being recognized as an important cause of neurological disease in humans. In many of these patients, the biochemical defect results from an abnormality of the mitochondrial genome. Respiratory chain defects involving complex II, which is entirely encoded by the nuclear genome, are comparatively rare. We report the clinical and biochemical findings in 2 elderly sisters who presented with late-onset neurodegenerative disease. In both patients, a partial deficiency of complex II (approximately 50% of control values) was shown to be present in mitochondria from muscle and platelets. The enzyme defect was not expressed in cultured skin fibroblasts or immortalized lymphocytes. There was an overexpression of the 70-kd flavoprotein subunit in muscle mitochondria from both patients, although we showed that this subunit is present in normal amounts in mitochondrial membranes. Our studies highlight the diversity of the clinical presentation of respiratory chain disease and that complex II deficiency should enter the differential diagnosis of certain patients with late-onset neurodegenerative disease.
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PMID:Deficiency of complex II of the mitochondrial respiratory chain in late-onset optic atrophy and ataxia. 896 54

Mammalian dihydroorotate dehydrogenase (EC 1.3.99.11), the fourth enzyme of pyrimidine de novo synthesis is located in the mitochondrial inner membrane with functional connection to the respiratory chain. From the cDNA of rat liver dihydroorotate dehydrogenase cloned in our laboratory the first complete sequence of a mammalian enzyme was deduced. Two hydrophobic stretches centered around residues 20 and 357, respectively, and a short N-terminal mitochondrial targeting sequence of 10 amino acids was proposed. A recombinant baculovirus containing the rat liver cDNA for dihydroorotate dehydrogenase was constructed and used for virus infection and protein expression in Trichoplusia ni cells. The targeting of the recombinant protein to mitochondria of the insect cells was monitored by activity determination of dihydroorotate dehydrogenase in subcellular compartments in comparison to succinate dehydrogenase activity (EC 1.3.5.1), which is a specific marker enzyme of the inner mitochondrial membrane. The results of subcellular distribution were verified by Western blotting with anti-dihydroorotate dehydrogenase immunoglobulins. The activity of the recombinant enzyme in the mitochondria of infected insect cells was found to be about 570-fold above the level of dihydroorotate dehydrogenase in rat liver mitochondria. By cation exchange chromatography of the Triton X-114 solubilisate of mitochondria, dihydroorotate dehydrogenase was purified to give a specific activity of 15 U/mg at pH 8.0. This was a marked progress over the six-step purification procedure of the enzyme from rat liver which resulted in a specific activity of 0.7 U/mg at pH 8.0. The characteristic flavin absorption spectrum obtained with the recombinant enzyme gave strong evidence that the rodent enzyme is a flavoprotein. By enzyme kinetic studies K(m) values for dihydroorotate and ubiquinone were 6.4 and 9.9 microM with the recombinant enzyme, and were 5.0 and 19.7 microM, respectively, with the rat liver enzyme. After expression of only truncated forms of human dihydroorotate dehydrogenase, the present successful generation of the complete rodent enzyme using insect cells and the efficient procedure will promote structure and function studies of the eukaryotic dihydroorotate dehydrogenases in comparison to the microbial enzyme.
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PMID:Rat dihydroorotate dehydrogenase: isolation of the recombinant enzyme from mitochondria of insect cells. 917 95

The sdh operon of Sulfolobus acidocaldarius DSM 639 is composed of four genes coding for the 63.1-kDa flavoprotein (SdhA), the 36.5-kDa iron-sulfur protein (SdhB), and the 32.1-kDa SdhC and 14.1-kDa SdhD subunits. The four structural genes of the sdhABCD operon are transcribed into one polycistronic mRNA of 4.2 kb, and the transcription start was determined by the primer extension method to correspond with the first base of the ATG start codon of the sdhA gene. The S. acidocaldarius SdhA and SdhB subunits show characteristic sequence similarities to the succinate dehydrogenases and fumarate reductases of other organisms, while the SdhC and SdhD subunits, thought to form the membrane-anchoring domain, lack typical transmembrane alpha-helical regions present in all other succinate:quinone reductases (SQRs) and quinol:ifumarate reductases (QFRs) so far examined. Moreover, the SdhC subunit reveals remarkable 30% sequence similarity to the heterodisulfide reductase B subunit of Methanobacterium thermoautotrophicum and Methanococcus jannaschii, containing all 10 conserved cysteine residues. Electron paramagnetic resonance (EPR) spectroscopic studies of the purified enzyme as well as of membranes revealed the presence of typical S1 [2Fe2S] and S2 [4Fe4S] clusters, congruent with the deduced amino acid sequences. In contrast, EPR signals for a typical S3 [3Fe4S] cluster were not detected. However, EPR data together with sequence information implicate the existence of a second [4Fe4S] cluster in S. acidocaldarius rather than a typical [3Fe4S] cluster. These results and the fact that the S. acidocaldarius succinate dehydrogenase complex reveals only poor activity with caldariella quinone clearly suggest a unique structure for the SQR of S. acidocaldarius, possibly involving an electron transport pathway from the enzyme complex into the respiratory chain different from those for known SQRs and QFRs.
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PMID:A succinate dehydrogenase with novel structure and properties from the hyperthermophilic archaeon Sulfolobus acidocaldarius: genetic and biophysical characterization. 928 13

The phylogeny of a previously unidentified, obligate laticifer-inhabiting bacterium associated with the papaya bunchy top disease was investigated. Portions of genes corresponding to those for 16S rRNA, the flavoprotein subunit of succinate dehydrogenase (SdhA), citrate synthase (GltA), and the 17-kDa rickettsial common antigen were isolated and sequenced from the non-cultivable bacterium from diseased plants. Comparative sequence analyses consistently indicated that the bacterium is a member of the alpha-subdivision of the Proteobacteria and of the genus Rickettsia. The rickettsia was detected by polymerase chain reaction in diseased, but not healthy, papaya tissues and in the leafhopper vector, Empoasca papayae, providing further evidence of the possible etiological role of the bacterium in the disease. Although Rickettsia have been found naturally in arthropods and can be pathogenic to humans and other vertebrates, this is the first evidence of its kind implicating a Rickettsia as a plant pathogen.
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PMID:Rickettsial relative associated with papaya bunchy top disease. 942 44

Thyroid-associated ophthalmopathy (TAO) is a progressive eye disorder associated with thyroid autoimmunity, particularly Graves' hyperthyroidism, which is generally considered to have an autoimmune etiology. Eye muscle membrane proteins reportedly of 55 and 64 kDa are the best markers of the ophthalmopathy. The main focus of our recent studies has been to purify the pertinent proteins from porcine eye muscle membranes and characterize them. The 64-kDa protein is now shown from a partial sequence and by Western blotting using specific antibody probes to be the flavoprotein (Fp) subunit of succinate dehydrogenase and to have a correct molecular mass of 67 kDa. The protein was purified and cleaved with cyanogen bromide, and the N-terminal region of an immunoreactive partial peptide was determined. The 20-amino acid porcine sequence so obtained matched one within the Fp subunits of human and bovine succinate dehydrogenases in 20 and 18 of these positions, respectively. Succinate dehydrogenase is both a citric acid cycle enzyme and a component (complex II) of the mitochondrial respiratory chain. It is thus essential for aerobic energy production and is highly conserved. The mature human and bovine Fp subunits are 92% homologous and have a molecular mass of approximately 67 kDa, the same as our redetermined value for the 64-kDa marker protein. Sera from patients with TAO and from those with Graves' hyperthyroidism without evident ophthalmopathy highlighted the 64-kDa marker protein in crude porcine eye muscle membranes and the Fp subunit of highly purified bovine succinate dehydrogenase at the identical position on Western blots. Anti-beef Fp antibodies were detected in sera from 67% of patients with active TAO of more than 1-yr duration, in 30% with stable TAO of more than 3-yr duration, and in 30% of patients with Graves' hyperthyroidism without ophthalmopathy, but in only 7% of age- and sex-matched normal subjects. As succinate dehydrogenase is bound to the matrix (inside) surface of the mitochondrial inner membrane, it is unlikely to be accessible to circulating autoantibodies. We would postulate that eye muscle damage in ophthalmopathy is probably caused by cytotoxic antibodies or CD+ T lymphocytes targeting a cell membrane antigen, such as the thyroid and eye muscle shared protein G2s, and that presentation of succinate dehydrogenase is secondary. On the other hand, an autoantibody response to succinate dehydrogenase may be a good marker of immune-mediated damage to the eye muscle fiber and may support the idea that the extraocular muscles are targets of the autoimmune reactions of TAO.
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PMID:The 64-kilodalton eye muscle protein is the flavoprotein subunit of mitochondrial succinate dehydrogenase: the corresponding serum antibodies are good markers of an immune-mediated damage to the eye muscle in patients with Graves' hyperthyroidism. 946 55

The first identified covalent flavoprotein, a component of mammalian succinate dehydrogenase, was reported 42 years ago. Since that time, more than 20 covalent flavoenzymes have been described, each possessing one of five modes of FAD or FMN linkage to protein. Despite the early identification of covalent flavoproteins, the mechanisms of covalent bond formation and the roles of the covalent links are only recently being appreciated. The main focus of this review is, therefore, one of mechanism and function, in addition to surveying the types of linkage observed and the methods employed for their identification. Case studies are presented for a variety of covalent flavoenzymes, from which general findings are beginning to emerge.
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PMID:Covalent attachment of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) to enzymes: the current state of affairs. 951 56

Anti-mitochondrial antibodies (anti-M7) in sera from patients with dilated cardiomyopathy and myocarditis recognize, besides mitochondrial antigens, bacterial sarcosine dehydrogenase. The common target antigen was identified as the covalently bound FAD of mitochondrial and bacterial flavoenzymes. Thus, anti-M7-positive serum reacted on Western blots exclusively with covalently flavinylated enzymes. The antigenic specificity of anti-M7 sera was reproduced by an antiserum raised in rabbits with 6-hydroxy-D-nicotine oxidase. The heart mitochondrial membrane antigen recognized by anti-M7 serum was identified as the flavoprotein subunit of succinate dehydrogenase, the antigens in rat liver mitochondrial matrix as the flavoenzymes dimethylglycine dehydrogenase and sarcosine dehydrogenase. Anti-M7 serum contained a specific anti-flavoenzyme antibody fraction. Nanomolar concentrations of FAD and riboflavin inhibited the immune reaction on Western blots and in ELISA, and incubation with FAD-agarose depleted the anti-M7 activity of the serum. N-terminally deleted dimethylglycine dehydrogenase proteins were only immunoprecipitated by anti-M7 sera when the FAD was covalently incorporated. An affinity constant (KD) of 10(-8) M was established for the anti-flavoenzyme antibodies by competitive ELISA. Of patients with cardiomyopathy and myocarditis, 36% and 25%, respectively, were anti-flavoenzyme-positive by Western blot and ELISA, but only two of 15 patients with other heart diseases and none of 50 healthy controls.
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PMID:Anti-mitochondrial antibodies in patients with dilated cardiomyopathy (anti-M7) are directed against flavoenzymes with covalently bound FAD. 952 96

Complex II (succinate-ubiquinone oxidoreductase) is an important enzyme complex in both the tricarboxylic acid cycle and the aerobic respiratory chains of mitochondria in eukaryotic cells and prokaryotic organisms. In this study, the amino acid sequences of the large (cybL) and small (cybS) subunits of cytochrome b in human liver complex II were deduced from cDNAs isolated by homology probing with mixed primers for the polymerase chain reaction. The mature cybL and cybS contain 140 and 103 amino acids, respectively, and show little similarity to the amino acid sequences of the subunits from other species in contrast to the highly conserved features of the flavoprotein (Fp) subunit and iron-sulfur protein (Ip) subunit. From hydrophobicity analysis, both cybL and cybS appear to have three transmembrane segments, indicating their role as membrane-anchors for the enzyme complex. Histidine residues, which are possible heme axial ligands in cytochrome b of complex II, were found in the second transmembrane segment of each subunit. The genes for cybL (SDHC) and cybS (SDHD) were mapped to chromosome 1q21 and 11q23, respectively by fluorescent in situ hybridization (FISH).
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PMID:Cytochrome b in human complex II (succinate-ubiquinone oxidoreductase): cDNA cloning of the components in liver mitochondria and chromosome assignment of the genes for the large (SDHC) and small (SDHD) subunits to 1q21 and 11q23. 953 30

Succinate:quinone oxidoreductase is a membrane-associated complex in mitochondria, often referred to as complex II, based on the fractionation scheme developed by Y. Hatefi and colleagues. It consists of four peptides, two of which are integral membrane proteins (15 and 12-13 kDa, respectively) and two others that are peripheral membrane proteins, i.e., a flavoprotein (Fp, 70 kDa) and an iron-protein (Ip, 27 kDa). The mature, functional complex contains a cytochrome in association with the membrane proteins, a flavin linked covalently to the largest peptide, and three iron-sulfur clusters in the 27-kDa subunit. The present review touches only briefly on the biochemical and biophysical properties of this complex. Instead, the focus is on the molecular-genetic studies that have become possible since the first genes from eukaryotes were cloned in 1989. The evolutionary conservation of the amino acid sequence of both the Fp and the Ip peptides has facilitated the cloning of these genes from a large variety of eukaryotic organisms by PCR-based methods. The review addresses questions related to the regulation of the expression of these genes, with an emphasis on mammals and yeast, for which most of the information is available. Four different genes have to be co-ordinately regulated. Transcriptional as well as posttranscriptional regulatory mechanisms have been observed in diverse organisms. Intriguing observations have been made in studies of this enzyme during the life cycle of organisms existing alternately under aerobic and anaerobic conditions. Naturally occurring or induced mutations in these genes have shed light on several questions related to the assembly of this complex, and on the relationship between structure and function. Four different peptides are imported into the mitochondria. They have to be modified, folded, and assembled. The stage is set for the exploration of highly specific changes introduced by site-directed mutagenesis. Until recently the genes were believed to be exclusively nuclear in all eukaryotes, but exceptions have since been found. This finding has relevance in the discussion of the evolution of mitochondria from prokaryotes. A highly conserved set of genes is found in prokaryotes, and some informative comparisons on gene organization and expression in prokaryotes and eukaryotes have been included.
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PMID:Molecular genetics of succinate:quinone oxidoreductase in eukaryotes. 959 77


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