Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new method was devised for the isolation of foetal and neonatal rat lvier mitochondria, giving higher yields than conventional methods. 2. During development from the perinatal period to the mature adult, the ratio of cytochrome oxidase/succinate-cytochrome c reductase changes. 3. The inner mitochondrial membrane of foetal liver mitochondria possesses virtually no osmotic activity; the permeability to sucrose decreases with increasing developmental age. 4. Foetal rat liver mitochondria possess only marginal respiratory control and do not maintain Ca2+-induced respiration; they also swell in respiratory-control medium in the absence of substrate. ATP enhances respiratory control and prevents swelling, adenylyl imidodiphosphate, ATP+atractyloside enhance the R.C.I. (respiratory control index), Ca2+-induced respiratory control and prevent swelling, whereas GTP and low concentrations of ADP have none of these actions. It is concluded that the effect of ATP depends on steric interaction with the inner mitochondrial membrane. 5. When 1-day pre-partum foetuses are obtained by Caesarean section and maintained in a Humidicrib for 90 min, mitochondrial maturation is "triggered", so that their R.C.I. is enhanced and no ATP is required to support Ca2+-dependent respiratory control or to inhibit mitochondrial swelling. 6. It is concluded that foetal rat liver mitochondria in utero do not respire, although they are capable of oxidative phosphorylation in spite of their low R.C.I. The different environmental conditions which the neonatal rat encounters ex utero enable the hepatic mitochondria to produce ATP, which interacts with the inner mitochondrial membrane to enhance oxidative phosphorylation by an autocatalytic mechanism.
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PMID:The maturation of the inner membrane of foetal rat liver mitochondria. 17 46

Proteolytic activities in bovine adrenocortical mitochondria were investigated using [14C-methyl]casein as a substrate. Washed mitochondria showed a low proteolytic activity at pH 7.5 or 8.2. ATP (5 mM) plus MgCl2 (7.5 mM) stimulated the proteolysis 9 times at pH 8.2. It was further demonstrated unequivocally by various approaches that the ATP-dependent proteolytic activity localizes in mitochondrial matrix. The activity of the solubilized protease was sensitive to N-ethylmaleimide, mersalyl acid, phenylmethylsulfonyl fluoride, o-vanadate, m-vanadate, vanadyl sulfate, and quercetin but not by oligomycin and ouabain. The ATP-dependent proteolytic activity was eluted at the position of 650,000 daltons on an Ultrogel AcA 22 column as a single symmetrical peak. The gel-filtered enzyme showed high specificity to ATP. GTP and UTP partially substituted ATP. ADP, AMP, tripolyphosphate, alpha, beta-methylene ATP, and beta, gamma-methylene ATP had little or no stimulating activity. ATP did not stimulate the activity in the absence of MgCl2. We measured ATP-dependent proteolytic activities in mitochondrial fractions from several tissues in rat and bovine. Adrenal cortex was one of the tissues of highest activity. In addition, we investigated the effect of adrenal atrophy on the ATP-dependent protease activity in rat adrenal. The ATP-dependent protease activity/adrenal decreased by dexamethasone treatment. The extent of the decrease was similar to that of cytochrome oxidase and succinate dehydrogenase, but smaller than that of cytochrome P-450.
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PMID:ATP-dependent protease in bovine adrenal cortex. Tissue specificity, subcellular localization, and partial characterization. 298 96

Transcripts for six Leishmania tarentolae maxicircle structural genes (cytochrome oxidase subunits I, II and III, cytochrome b, human mitochondrial unidentified reading frames 4 and 5) and several unidentified open reading frames were mapped, and the locations of the 5' ends determined by primer runoff analysis. All genes studied here are transcribed from the same strand as the 12S and 9S ribosomal RNAs except for the cytochrome oxidase subunit I gene. In two cases (ORF3 and ORF4, ORF5 and ORF6), a single transcript covers two contiguous overlapping reading frames. The 5' ends of the RNAs are located 20-64 nt from the putative translation initiation codons. Primary transcripts from a mitochondrial RNA preparation were 5' end-labeled with guanylyltransferase and alpha -32P-GTP; the major labeled species comigrated with the 12S and 9S mitochondrial rRNAs, and in addition there were at least four higher molecular weight labeled species.
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PMID:Mapping and 5' end determination of kinetoplast maxicircle gene transcripts from Leishmania tarentolae. 299 21

Paramecium aurelia mitochondrial (mt) DNA fragments carrying the coding regions for two proteins, P1 (in the region adjacent to the origin of replication) and COII (subunit II of cytochrome oxidase), were used to study mt gene expression. The sequence for the portion of mtDNA containing P1 has already been described [Pritchard et al., Gene 44 (1986) 243-253]. The complete nucleotide sequence of the portion containing the COII gene is presented here. An 18.5-kDa protein was produced in maxicells when a fragment containing a major portion of the sequence coding for P1 was used. This fragment and a fragment carrying the COII gene were cloned into the expression vector pTRPLE', and antibodies were raised against the resulting fusion proteins in an Escherichia coli lysate. Western blots of Paramecium mt extracts identified two proteins, one 21 kDa (COII) and the other 23.5 kDa (P1). The size of the P1 protein is in agreement with the size of the open reading frame in that region of mitochondrial DNA. Based on extensive amino acid homology to the Paramecium gene and limited homology to COII genes from other organisms, the COII gene in another ciliate, Tetrahymena pyriformis, was identified just upstream of the small subunit rDNA in previously published sequences (Schnare et al., 1986). The size of the COII gene and the homology with the COII gene from Tetrahymena suggest that ATC, ATT, GTG and GTC could be used as translational initiators in Paramecium mitochondria.
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PMID:Identification of Paramecium mitochondrial proteins using antibodies raised against fused mitochondrial gene products. 303 45

We have investigated the energy requirement of mitochondrial protein import with a simplified system containing only isolated yeast mitochondria, energy sources and a purified precursor protein. This precursor was a fusion protein composed of 22 residues of the cytochrome oxidase subunit IV pre-sequence fused to mouse dihydrofolate reductase. Import of this protein required not only an energized inner membrane, but also ATP. ATP could be replaced by GTP, but not by CTP, TTP or non-hydrolyzable ATP analogs. Added ATP did not increase the membrane potential of respiring mitochondria; it supported import even if the proton-translocating mitochondrial ATPase and the entry of ATP into the matrix were blocked. We conclude that ATP exerts its effect on mitochondrial protein import outside the inner membrane.
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PMID:Both ATP and an energized inner membrane are required to import a purified precursor protein into mitochondria. 303 90

The mouse cytochrome oxidase (COX) Vb promoter contains three sequence motifs with partial or full consensus for YY-1 and GTG factor binding and a CArG box, located between positions -480 and -390. Individually, all three motifs stimulated transcription of the TKCAT promoter, and bound distinctly different proteins from the liver and differentiated C2C12 nuclear extracts. Collectively, these motifs, together with the downstream flanking sequence, -378 to -320, suppressed the transcription activity of heterologous promoters, thymidine kinase-chloramphenicol acetyltransferase (TKCAT) and COXIV/CAT. The transcription activities of both TKCAT and COXIV/CAT constructs were induced 3-4-fold during induced myogenesis of C2C12 cells. The downstream CArG-like motif binds transcription factor YY-1, while the upstream YY-1-like motif binds to a yet unidentified factor. Co-expression with intact YY-1, but not that lacking the DNA binding domain suppressed the transcriptional activity. Mutations targeted to the CArG-like motif abolished the suppressive effect of the negative enhancer and the inducibility of the promoter during myogenic differentiation. Our results suggest that the activity of the negative enhancer may determine the level of expression of the COX Vb gene in different tissues.
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PMID:Regulation of murine cytochrome oxidase Vb gene expression in different tissues and during myogenesis. Role of a YY-1 factor-binding negative enhancer. 903 8

The catalytic activity and molecular aspects of Thiobacillus novellus cytpchrome c oxidase were affected by ATP. The steady-state kinetics in the oxidation of ferrocytochrome c by the oxidase varied with the presence or absence of ATP; the [S]-v curve of the reaction was sigmoid in the absence of ATP whereas it was a Michaelis-Menten-type hyperbola in the presence of 700 microM ATP. The oxidase was a dimer of the minimal structural subunit consisting of one molecule each of two subunits in the presence of Tween 20 and in the absence of ATP. The dimer dissociated into monomers in the presence of 700 microM ATP. The trough at 452 nm seen in the second derivative absorption spectrum of the CO compound of the oxidase in the absence of ATP, a characteristic of the cytochrome a component of cytochrome aa3, dissappeared in the presence of 700 microM ATP. However, ADP, AMP, GTP, CTP and UTP had little affect on both the [S]-v curve and the molecular mass of the oxidase when used in place of ATP.
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PMID:The effects of several nucleotides on the molecular state and catalytic activity of Thiobacillus novellus cytochrome c oxidase. ATP affects the oxidase uniquely. 1049 Nov 45

Recently, the bacterial elongation factor LepA was identified as critical for the accuracy of in vitro translation reactions. Extremely well conserved homologues of LepA are present throughout bacteria and eukaryotes, but the physiological relevance of these proteins is unclear. Here we show that the yeast counterpart of LepA, Guf1, is located in the mitochondrial matrix and tightly associated with the inner membrane. It binds to mitochondrial ribosomes in a GTP-dependent manner. Mutants lacking Guf1 show cold- and heat-sensitive growth defects on non-fermentable carbon sources that are especially pronounced under nutrient-limiting conditions. The cold sensitivity is explained by diminished rates of protein synthesis at low temperatures. At elevated temperatures, Guf1-deficient mutants exhibit defects in the assembly of cytochrome oxidase, suggesting that the polypeptides produced are not functional. Moreover, Guf1 mutants exhibit synthetic growth defects with mutations of the protein insertase Oxa1. These observations show a critical role for Guf1 in vivo. The observed defects in Guf1-deficient mitochondria are consistent with a function of Guf1 as a fidelity factor of mitochondrial protein synthesis.
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PMID:The membrane-bound GTPase Guf1 promotes mitochondrial protein synthesis under suboptimal conditions. 1844 68

Candida albicans is both a major fungal pathogen and a member of the commensal human microflora. The morphological switch from yeast to hyphal growth is associated with disease and many environmental factors are known to influence the yeast-to-hyphae switch. The Ras1-Cyr1-PKA pathway is a major regulator of C. albicans morphogenesis as well as biofilm formation and white-opaque switching. Previous studies have shown that hyphal growth is strongly repressed by mitochondrial inhibitors. Here, we show that mitochondrial inhibitors strongly decreased Ras1 GTP-binding and activity in C. albicans and similar effects were observed in other Candida species. Consistent with there being a connection between respiratory activity and GTP-Ras1 binding, mutants lacking complex I or complex IV grew as yeast in hypha-inducing conditions, had lower levels of GTP-Ras1, and Ras1 GTP-binding was unaffected by respiratory inhibitors. Mitochondria-perturbing agents decreased intracellular ATP concentrations and metabolomics analyses of cells grown with different respiratory inhibitors found consistent perturbation of pyruvate metabolism and the TCA cycle, changes in redox state, increased catabolism of lipids, and decreased sterol content which suggested increased AMP kinase activity. Biochemical and genetic experiments provide strong evidence for a model in which the activation of Ras1 is controlled by ATP levels in an AMP kinase independent manner. The Ras1 GTPase activating protein, Ira2, but not the Ras1 guanine nucleotide exchange factor, Cdc25, was required for the reduction of Ras1-GTP in response to inhibitor-mediated reduction of ATP levels. Furthermore, Cyr1, a well-characterized Ras1 effector, participated in the control of Ras1-GTP binding in response to decreased mitochondrial activity suggesting a revised model for Ras1 and Cyr1 signaling in which Cyr1 and Ras1 influence each other and, together with Ira2, seem to form a master-regulatory complex necessary to integrate different environmental and intracellular signals, including metabolic status, to decide the fate of cellular morphology.
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PMID:Mitochondrial Activity and Cyr1 Are Key Regulators of Ras1 Activation of C. albicans Virulence Pathways. 2631 37