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:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report that the mitochondrial genome of Chlamydomonas moewusii has a 22 kb circular map and thus contrasts with the mitochondrial genome of Chlamydomonas reinhardtii, which is linear and about 6 kb shorter. Overlapping restriction fragments spanning over 90% of the C. moewusii mitochondrial DNA (mtDNA) were identified in a clone bank constructed using a Sau3AI partial digest of a C. moewusii DNA fraction enriched for mtDNA by preparative CsCl density gradient centrifugation. Overlapping Sau3AI clones were identified by a chromosome walk initiated with a clone of C. moewusii mtDNA. The mtDNA map was completed by Southern blot analysis of the C. moewusii mtDNA fraction using isolated mtDNA clones. Regions that hybridized to C. reinhardtii or wheat mitochondrial gene probes for subunit I of cytochrome oxidase (cox1), apocytochrome b (cob), three subunits of NADH dehydrogenase (nad1, nad2 and nad5) and the small and the large ribosomal RNAs (rrnS and rrnL, respectively) were localized on the C. moewusii mtDNA map by Southern blot analysis. The results show that the order of genes in the mitochondrial genome of C. moewusii is completely rearranged relative to that of C. reinhardtii.
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PMID:Cloning and characterization of the Chlamydomonas moewusii mitochondrial genome. 175 45

The interaction of quinones (menadione and duroquinone) with DT-diaphorase and mitochondrial electron transport chain translocators at low (120 mosM) and high (400 mosM) values of the medium tonicity in the quinone concentration range of 6-90 microM was studied. It was shown that with a rise in menadione (K3) concentration the number of electron transport carriers interacting with it increase. At K3 concentration of 6 microM the latter is reduced by DT-diaphorase and fully oxidized via the Q-cycle. At K3 concentration of 15 microM the latter is also reduced by DT-diaphorase via the Q-cycle, but in this case the oxidation is incomplete (about 30% K3H2 is oxidized by the terminal part of the respiratory chain). At 90 microM K3 50% of quinone is reduced by DT-diaphorase and 50% by the respiratory chain NADH dehydrogenase complex enzymes; about 30% of K3H2 is oxidized via the Q-cycle, about 20%--by the terminal part of the respiratory chain and about 50%--by O2 without cytochrome oxidase. Unlike menadione, duroquinone (6-90 microM) is reduced only by DT-diaphorase and is oxidized in all cases by cytochrome oxidase. It was shown that the increase in the mitochondrial matrix volume in low tonicity media decreases the rate of the DT-diaphorase shunt operation.
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PMID:[Interaction of menadione and duroquinone with Q-cycle during DT-diaphorase function]. 177 18

The nucleotide sequence of a segment of the mitochondrial DNA from three Drosophila species (D. erecta, D. eugracilis, and D. takahashii), belonging to different subgroups of the melanogaster group has been determined. The segment encompasses three complete tRNA genes (tRNAtrp, tRNAcys, and tRNAtyr) and portions of two protein-coding genes: the subunit 2 of the NADH dehydrogenase (ND2) and the subunit 1 of the cytochrome oxidase (COI). Comparisons also involve homologous sequences already known for four other Drosophila species of the melanogaster group. Length differences were confined in the intergenic region where a long stretch of AT repeats was observed in one of the species analyzed. The three tRNA genes exhibit very different evolutionary rates, the most slowly evolving one, tRNAtyr, is adjacent to the 5' end of COI; tRNAs in similar positions have been previously shown to evolve slowly because they are probably involved in transcript processing. Although the rate of synonymous substitutions was very similar between ND2 and COI genes there were strong discrepancies between them in terms of the number of nonsynonymous substitutions. Differences have also been found in G + C content of the genes, which are likely to be linked to different selective pressures. There is a reduction in G + C content in the region where selective constraints are reduced. This suggests the existence of different levels of constraints along the sequenced segment. An overall analysis of the types of substitutions showed a decrease in A + T content during the course of evolution of the species.
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PMID:Mitochondrial DNA sequence divergence in the Melanogaster and oriental species subgroups of Drosophila. 192 Apr 52

The amino acid sequences of 15 sugar permeases of the bacterial phosphoenolpyruvate-dependent phosphotransferase system (PTS) were divided into four homologous segments, and these segments were analyzed to give phylogenetic trees. The permease segments fell into four clusters: the lactose-cellobiose cluster, the fructose-mannitol cluster, the glucose-N-acetylglucosamine cluster, and the sucrose-beta-glucoside cluster. Sequences of the glucitol and mannose permeases (clusters 5 and 6, respectively) were too dissimilar to establish homology with the other permeases, but short regions of statistically significant sequence similarities were noted. The functional and structural relationships of these permease segments are discussed. Some of the homologous PTS permeases were found to exhibit sufficient sequence similarity to subunits 4 and 5 of the eukaryotic mitochondrial NADH dehydrogenase complex to suggest homology. Moreover, subunits 4 and 5 of this complex appeared to be homologous to each other, suggesting that these PTS and mitochondrial proteins comprise a superfamily. The integral membrane subunits of the evolutionarily divergent mannose PTS permease, the P and M subunits, exhibited limited sequence similarity to subunit 6 of the mitochondrial F1F0-ATPase and subunit 5b of cytochrome oxidase, respectively. These results suggest that PTS sugar permeases and mitochondrial proton-translocating proteins may be related, although the possibility of convergent evolution cannot be ruled out.
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PMID:Evolutionary relationships among the permease proteins of the bacterial phosphoenolpyruvate: sugar phosphotransferase system. Construction of phylogenetic trees and possible relatedness to proteins of eukaryotic mitochondria. 192 Apr 54

We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea star Pisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNA(glu) and tRNA(thr) are 3' to 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules.
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PMID:Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the mitochondrial DNA of the sea star Pisaster ochraceus. 197 16

Bovine heart submitochondrial particles (SMP) were exposed to continuous fluxes of hydroxyl radical (.OH) alone, superoxide anion radical (O2-) alone, or mixtures of .OH and O2-, by gamma radiolysis in the presence of 100% N2O (.OH exposure), 100% O2 + formate (O2- exposure), or 100% O2 alone (.OH + O2- exposure). Hydrogen peroxide effects were studied by addition of pure H2O2. NADH dehydrogenase, NADH oxidase, succinate dehydrogenase, succinate oxidase, and ATPase activities (Vmax) were rapidly inactivated by .OH (10% inactivation at 15-40 nmol of .OH/mg of SMP protein, 50-90% inactivation at 600 nmol of .OH/mg of SMP protein) and by .OH + O2- (10% inactivation at 20-80 nmol of .OH + O2-/mg of SMP protein, 45-75% inactivation at 600 nmol of .OH + O2-/mg of SMP protein). Importantly, O2- was a highly efficient inactivator of NADH dehydrogenase, NADH oxidase, and ATPase (10% inactivation at 20-50 nmol of O2-/mg of SMP protein, 40% inactivation at 600 nmol of O2-/mg of SMP protein), a mildly efficient inactivator of succinate dehydrogenase (10% inactivation at 150 nmol of O2-/mg of SMP protein, 30% inactivation at 600 nmol of O2-/mg of SMP protein), and a poor inactivator of succinate oxidase (less than 10% inactivation at 600 nmol of O2-/mg of SMP protein). H2O2 partially inactivated NADH dehydrogenase, NADH oxidase, and cytochrome oxidase, but even 10% loss of these activities required at least 500-600 nmol of H2O2/mg of SMP protein. Cytochrome oxidase activity (oxygen consumption supported by ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine) was remarkably resistant to oxidative inactivation, with less than 20% loss of activity evident even at .OH, O2-, OH + O2-, or H2O2 concentrations of 600 nmol/mg of SMP protein. Cytochrome c oxidase activity, however (oxidation of, added, ferrocytochrome c), exhibited more than a 40% inactivation at 600 nmol of .OH/mg of SMP protein. The .OH-dependent inactivations reported above were largely inhibitable by the .OH scavenger mannitol. In contrast, the O2(-)-dependent inactivations were inhibited by active superoxide dismutase, but not by denatured superoxide dismutase or catalase. Membrane lipid peroxidation was evident with .OH exposure but could be prevented by various lipid-soluble antioxidants which did not protect enzymatic activities at all.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The oxidative inactivation of mitochondrial electron transport chain components and ATPase. 216 88

The gene organization of the Peking duck mitochondrial (mt)DNA has been deduced through heterologous hybridization using different cloned fragments of the chicken or Japanese quail mitochondrial genome as probes. As in the chicken, and other gallinaceous birds, the Peking duck mtDNA displays a novel gene order which differs from that of other vertebrates by the unusual localization of the tRNA(Glu) and ND6 genes next to the displacement (D) loop region of the molecule. The position of these genes with respect to the mitochondrial D-loop region, the cytochrome oxidase subunits I, II and III, the NADH dehydrogenase subunit I and the ribosomal (r) RNAs, was confirmed by the partial nucleotide sequence of cloned mtDNA fragments.
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PMID:Gene organization of the Peking duck mitochondrial genome. 239 Jul 86

The assembly of mitochondrially and cytoplasmically translated subunits of NADH dehydrogenase in the inner mitochondrial membrane was studied in rat hepatoma cultures. A polyclonal antibody to the purified bovine heart holoenzyme, which reacted with comigrating proteins of both rat liver and hepatoma mitochondria on immunoblots, precipitated 25-30 [35S]methionine-labeled proteins from hepatoma cell lysates. Six of these were sensitive to an inhibitor of mitochondrial translation (chloramphenicol), resistant to an inhibitor of cytosolic translation (cycloheximide), and were not present in cytochrome oxidase. By these criteria, six NADH dehydrogenase subunits are identified as being translated on mitochondrial ribosomes. The metabolic properties of the three most prominent of these at 51, 43, and 11 kDa were studied in more detail. Mitochondrial and nuclear-coded polypeptides assemble into NADH dehydrogenase at different rates as measured by incorporation of pulse-labeled proteins into immunoprecipitable enzyme. Nuclear-coded, imported polypeptides appear immediately after a pulse with [35S]methionine and retain constant stoichiometry. Mitochondrially coded proteins, although rapidly translated, appear at peak levels at different times between 0 and 12 h of chase in the immunoprecipitated enzyme. Ongoing synthesis and import of nuclear-coded proteins is necessary for mitochondrially coded proteins to be assembled. Excess, unassembled mitochondrially translated subunits are degraded in an oligomycin-sensitive manner. These data are consistent with a model in which a scaffold of imported proteins forms the inner core of the enzyme, and later arriving mitochondrially translated proteins attach to the scaffold in a time-dependent manner.
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PMID:Respiratory chain-linked NADH dehydrogenase. Mechanisms of assembly. 239 60

Rotenone-sensitive NADH dehydrogenase activity and Lubrol stimulation of cytochrome oxidase activity were measured to assess the opposite membrane polarity of beef heart mitoplast and inside-out particle preparations. The ATP-Pi exchange activity of mitoplasts was not affected by their incubation at pH 8.9 in the presence of 5 mM EDTA (a treatment known to extract coupling factor B (F beta) from submitochondrial particles), nor was it stimulated by the addition of F beta to intact and alkaline treated mitoplast preparations. In contrast, the exchange activity of inside-out particles was decreased 18 fold by the alkaline/EDTA treatment and was almost completely restored by the addition of F beta to F beta-depleted particles. From these results it is concluded that in beef heart mitochondria, the coupling factor F beta is bound to the matrix-side of the inner mitochondrial membrane.
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PMID:Evidence that coupling factor B is bound to the matrix side of the inner mitochondrial membrane. 256 42

We isolated from a HeLa genomic library 38 plaques that hybridized to total mitochondrial (mt) DNA isolated from human placenta. One clone (HLmt-17.8) hybridized to a 740 base-pair (12 S ribosomal RNA gene and displacement loop) mtDNA probe and was characterized in more detail. Within its 17.8 x 10(3) base-pair insert a 1.6 x 10(3) base-pair mtDNA fragment was similar to three non-sequential coding genes of human mtDNA, including a part of the 12 S ribosomal RNA (684-971), the cytochrome oxidase I (6553-7302), and two NADH dehydrogenase [ND4L/ND4] (10,606-11,159). The similarity to human mtDNA sequences was 92.0%, 92.3% and 92.4%, respectively, the highest degree of similarity to human mtDNA so far reported. This is also the first report of several adjacent mtDNA-like sequences in cellular chromosomes. The mtDNA-like sequences in HLmt-17.8 was found in the DNAs of human placenta, freshly isolated human leukocytes, foreskin and several human cell lines; but it was not present in other primates or lower organisms. The HLmt-17.8 mtDNA-like region appears to be a pseudogene that transferred into the nucleus in humans more recently than nine million years ago.
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PMID:Three separate mitochondrial DNA sequences are contiguous in human genomic DNA. 261 44


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