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)

Closed protein-phospholipid particles (proteoliposomes), obtained by self-assembly method, are capable to generate and to maintain the membrane potential in the case if their protein complex is represented by: a) a complex of mitochondrial ATPase; b) a complex of cytochrome oxidase and cytochrome c and c) bacteriorhodopsin from Halobacterium halobium; and their phospholipid component is represented by phosphatidylethanolamine or by a mixture of mitochondrial phospholipids. Only cytochromoxidase and bacteriorhodopsin (but not ATPase) proteoliposomes with phosphatidylserine are active. Cardiolipin also is not active in experiments with ATPase. Phosphatidylcholine produces in all the cases proteoliposomes incapable of maintaining the membrane potential. It is concluded that the inefficiency of phosphatidylcholine in the formation of proteoliposomes, generating the membrane potential, is due to the impossibility of obtaining closed membrane forms with a high electric resistance. The inefficiency of phosphatidylserine and cardiolipine, in the case of ATPase protein component of proteoliposomes, may be due to a specific requirement of this generator of the membrane potential in phosphatidylethanolamine.
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PMID:[Role of phospholipids in the generation of membrane potentials by proteoliposomes]. 17 54

The mRNA levels of ATPase beta, ATPase 6, cytochrome oxidase (COX) VIb and COX I subunits were found to be 2.4-13.8-fold higher in brown adipose tissue (BAT) than in heart, skeletal muscle, brain and liver of mice. The comparison with tissue contents of ATPase and COX revealed that the selective, 5-11-fold reduction of ATPase in BAT is not caused by decreased transcription of ATPase genes. Likewise, the ATPase beta and COX VIb mRNA levels in cultured brown adipocytes were also not influenced by norepinephrine, which activated the expression of the UCP gene by two orders of magnitude. The results indicate that the biosynthesis of mitochondrial ATPase in BAT is post-transcriptionally regulated.
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PMID:Low content of mitochondrial ATPase in brown adipose tissue is the result of post-transcriptional regulation. 166 83

We describe a collection of nuclear respiratory-defective mutants (pet mutants) of Saccharomyces cerevisiae consisting of 215 complementation groups. This set of mutants probably represents a substantial fraction of the total genetic information of the nucleus required for the maintenance of functional mitochondria in S. cerevisiae. The biochemical lesions of mutants in approximately 50 complementation groups have been related to single enzymes or biosynthetic pathways, and the corresponding wild-type genes have been cloned and their structures have been determined. The genes defined by an additional 20 complementation groups were identified by allelism tests with mutants characterized in other laboratories. Mutants representative of the remaining complementation groups have been assigned to one of the following five phenotypic classes: (i) deficiency in cytochrome oxidase, (ii) deficiency in coenzyme QH2-cytochrome c reductase, (iii) deficiency in mitochondrial ATPase, (iv) absence of mitochondrial protein synthesis, and (v) normal composition of respiratory-chain complexes and of oligomycin-sensitive ATPase. In addition to the genes identified through biochemical and genetic analyses of the pet mutants, we have cataloged PET genes not matched to complementation groups in the mutant collection and other genes whose products function in the mitochondria but are not necessary for respiration. Together, this information provides an up-to-date list of the known genes coding for mitochondrial constituents and for proteins whose expression is vital for the respiratory competence of S. cerevisiae.
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PMID:PET genes of Saccharomyces cerevisiae. 221 20

The respiratory deficiency of two noncomplementing mutants of Saccharomyces cerevisiae (C41 and N28) has been shown to be due to mutations in HEM2, the structural gene for delta-aminolevulinate dehydratase. The mutants are unable to convert delta-aminolevulinic acid to porphobilinogen and are not complemented by the hem2 mutant GL4 (Gollub, E. G., Liu, K.-P., Dagan, J., Adlersberg, M., and Sprinson, D. B. (1977) J. Biol. Chem. 252, 2846-2854). A gene capable of complementing the respiratory deficiency of C41 and N28 has been cloned by transformation of a hem2 mutant with a recombinant plasmid library of wild type yeast nuclear DNA. The sequence of the protein encoded by the cloned gene exhibits extensive homology to the recently reported sequence of human delta-aminolevulinate dehydratase (Wetmur, J. G., Bishop, D. F., Cantelmo, C., and Desnick, R. J. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7703-7707). Several approaches were taken to study the effect of heme on transcription of PET genes known to code for subunit components of respiratory enzymes and of mitochondrial ATPase. The first involved measurements of the steady state levels of mRNAs for subunit 5 of cytochrome oxidase and the beta subunit of F1 ATPase in wild type and in a hem2 mutant. Secondly, transcription of the genes coding for the cytochrome oxidase and ATPase subunits as well as of the COR1 gene coding for the 44-kDa core 1 subunit of coenzyme QH2-cytochrome c reductase was quantitated by fusing the 5'-flanking and part of the coding region of each gene to the lacZ gene of Escherichia coli in vectors capable of integrating into yeast chromosomal DNA. The different lacZ fusions were integrated into nuclear DNA of a wild type strain and of hem2 mutants allowing expression of beta-galactosidase to be studied as a function of intracellular heme. These experiments indicate that the promoters of the genes for subunits of the respiratory complexes are regulated by heme. In contrast, the expression of the ATPase subunit appears to be heme-independent. Because neither subunit 5 of cytochrome oxidase nor the core 1 subunit of coenzyme QH2-cytochrome c reductase are hemoproteins, transcriptional regulation by heme may be a general mechanism for controlling the synthesis of mitochondrial proteins involved in respiration.
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PMID:Characterization of the yeast HEM2 gene and transcriptional regulation of COX5 and COR1 by heme. 244 51

The 3'-termini of the mRNAs for subunit II of the cytochrome oxidase (COX II) and for the alpha-subunit of the mitochondrial ATPase (ATPA) have been determined in Oenothera mitochondria by two independent methods. Analysis of both transcripts by S1 protection experiments and of cloned cDNAs show an identical terminal 50 nucleotide sequence, to which homology is found 3' to some gene sequences in the maize mitochondrial genome. These regions can be folded into potential secondary structures similar to bacterial terminators.
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PMID:Transcript termini of messenger RNAs in higher plant mitochondria. 287 33

Neurospora mitochondrial DNA is transcribed into long molecules containing the information of several genes. Processing leads to formation of functionally active RNAs. It has been shown previously that when tRNA sequences are present in these transcripts excision of mRNAs occurs at the acceptor stem of these tRNA sequences. We have investigated the processing of precursor RNAs transcribed from a region of the mitochondrial genome devoid of tRNA genes. This region comprises the genes encoding subunit 6 of the mitochondrial ATPase, subunit 2 of cytochrome aa3 and a mitochondrial ATPase proteolipid-like gene. We have proved that a common precursor of the putative mRNAs of these genes exists and we have determined the positions of the 5' and 3' ends of processing intermediates and of the mature mRNAs. We will discuss possible processing routes and secondary structures that substitute for tRNA sequences as processing sites.
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PMID:Processing of precursor RNAs from mitochondria of Neurospora crassa. 295 78

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

Among 979 non-glycerol growers of the yeast Schizosaccharomyces pombe, 40 strains were found to be deficient in the mitochondrial ATPase activity. Three of them exhibited an alteration in either the alpha or beta subunits of the F1ATPase. The alpha subunit was not immunodetected in the A23/13 mutant. The beta subunit was not immuno-detected in the B59/1 mutant. The existence of these two mutants shows that the alpha and beta subunits can be present independently of each other in the inner mitochondrial membrane. The beta subunit of the mutant F25/28 had a slower electrophoretic mobility than that of the wild-type beta subunit. This phenotype indicates abnormal processing or specific modification of the beta subunit. All mutants showed reduced activities of the NADH-cytochrome c reductase and of the cytochrome oxidase and a decreased synthesis of cytochrome aa3 and cytochrome b. This pleiotropic phenotype appears to result from specific modifications in the mitochondrial protein synthesis. The mitochondrial synthesis of four polypeptides (three cytochrome oxidase and one cytochrome b subunits) was markedly decreased or absent while three new polypeptides (Mr = 54000, 20000 and 15000) were detected in all the mutants analysed. This observation suggests that a functional F1ATPase is necessary for the correct synthesis and/or assembly of the mitochondrially made components of the cytochrome oxidase and cytochrome b complexes.
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PMID:Alterations of the alpha or beta subunits of the mitochondrial ATPase in yeast mutants. 621 96

1. Mitochondrial translation products of yeast Saccharomyces cerevisiae were separated according to charge as well as molecular weight by a highly resolving two dimensional electorphoretic technique (isoelectric focusing in the first dimension ana SDS-electrophoresis in the second dimension). 2. The major protein components (the oligomeric form of subunit 9 of mitochondrial ATPase, var 1, cytochrome oxidase subunits I, II and III, subunit 6 of mitochondrial ATPase and cytochrome b apoprotein) were identified either from their mobility in SDS-electrophoresis or by using mit- mutants defective in certain mitochondrially made polypeptides. 3. This method allowed the separation of subunit III of cytochrome oxidase and subunit 6 of mitochondrial ATPase which cannot be resolved by conventional SDS-polyacrylamide gel electrophoresis. 4. Subunit II of cytochrome oxiodase resolves in two spots of similar pI values and subunit 6 of mitochondrial ATPase resolves in two spots of similar molecular weight. In both cases the double spots disappear simultaneously following a single mutation in the coresponding structural gene. 5. Total mitochondrial proteins were also resolved two-dimensionally revealing over 100 components. The mitochondrial translation products, with the exception of subunit 9 of mitochondrial ATPase, could be easily recognized among the other mitochondrial proteins.
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PMID:Biogenesis of mitochondria. Two-dimensional electrophoretic analysis of mitochondrial translation products in yeast. 625 Jun 20

1. Two oligomycin-resistant strains of Saccharomyces cerevisiae have been isolated and shown to have mutations in the oli2 region of the mitochondrial DNA. On solid media containing a non-fermentable energy source, the mutant strains were able to grow only slowly at 28 degrees C and not at all at 18 degrees C or 36 degrees C. 2. When grown in a glucose-limited chemostat at 28 degrees C, the mutant strains were almost completely defective in oxidative metabolism. The mutant mitochondria contained significant levels of all respiratory enzymes, and an active, oligomycin-sensitive ATPase, but the ATP-32Pi exchange activity and P : O ratio were very low. 3. The mutations in these strains are genetically closely linked to mit mutations which have been shown to affect a 20 000-dalton ATPase subunit (Roberts, H., Choo, W.M., Murphy, M., Marzuki, S., Lukins, H.B. and Linnane, A.W. (1979) FEBS Lett. 108, 501-504). Since the mitochondrial ATPase in these mutant strains appears to be fully assembled, the defect in the coupling mechanism is probably a result of a small alteration in the structure of the 20 000-dalton ATPase subunit. 4. When the mutant strains were grown at 18 degrees C, the mitochondria had very low cytochrome oxidase activities, and reduced levels of cytochrome aa3. The largest subunit (Mr 40 000) of this enzyme was not synthesized.
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PMID:Biogenesis of mitochondria. oli2 Mutations affecting the coupling of oxidation to phosphorylation in Saccharomyces cerevisiae. 625 66


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