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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vitro culture of mammalian preimplantation embryos is associated with various developmental disorders such as retardation in development and cell damage. The molecular mechanisms underlying these processes are poorly understood. One of the possible reasons may be the unphysiologically high oxygen concentration used for culture. Four-day-old rabbit blastocysts were cultured with 5% O2 (physiologic oxygen concentration) or 20% O2 (usually used for in vitro culture) for 4 hr. Differences in gene expression were analysed by differential display reverse-transcriptase polymerase chain reaction (DD RT-PCR). Thirty-two differentially expressed RNA bands were found. Two of them revealed a high sequence homology to the equine NADH-ubiquinone oxidoreductase chain 2 (ND2), a subunit of complex I of the respiratory chain. mRNA expression of ND2 was increased in blastocysts cultured with the higher oxygen concentration. Increased expression of ND2 was confirmed by semiquantitative and semiquantitative competitive RT-PCR.
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PMID:Increased expression of NADH-ubiquinone oxidoreductase chain 2 (ND2) in preimplantation rabbit embryos cultured with 20% oxygen concentration. 950 90

The proton-pumping NADH:ubiquinone oxidoreductase (complex I) of Escherichia coli is composed of 13 different subunits. The corresponding genes are organized in the nuo-operon (from NADH:ubiquinone oxidoreductase) at min 51 of the E. coli chromosome. To study the structure and function of this complex enzyme, a suitable purification protocol yielding sufficient amount of a stable protein is needed. Here, we report the overproduction of complex I in E. coli and a novel isolation procedure of the complex. Overexpression of the nuo-operon on the chromosome was achieved by replacing its 5'-promotor region with the phage-T7 RNA polymerase promotor and by expressing the genes with the T7 RNA polymerase coded on an inducible plasmid. It is shown by means of enzymatic activity and EPR spectroscopy of cytoplasmic membranes that complex I is overproduced 4-fold after induction. Complex I was isolated by chromatographic steps performed in the presence of dodecyl maltoside. The preparation comprises all subunits and known cofactors and exhibits a high enzymatic activity and inhibitor sensitivity. Due to its stability over a wide pH range and at very high salt concentrations, this preparation is well suited for structural investigations.
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PMID:Overexpression of the Escherichia coli nuo-operon and isolation of the overproduced NADH:ubiquinone oxidoreductase (complex I). 1058 49

We describe here the complete sequence (58,507 bp) of the mitochondrial genome of the brown alga Pylaiella littoralis (Ectocarpales). This molecule displays an AT content of 62.0% and contains seventy-nine genes, most of them (73) encoded on one strand. They include the usual mitochondrial set of protist genes and a number of rarer genes. Among these, several ribosomal protein genes and the rn5 were identified. Twenty-four tRNA genes are present in this genome, insufficient to decode all genes. The other conspicuous features of this molecule are: a large (3018 nucleotides) in-frame insertion of unknown function in the cox2 gene; the presence of two different lineages of group II introns, including complete reverse transcriptase-like genes, one in the cox1 and the other in the rnl gene; the concomitant occurrence of a T7-like RNA polymerase and of several well-conserved alpha-proteobacterial-type promoters; and a small nad11 gene, coding for the first domain only of this NADH dehydrogenase subunit. Altogether, the mitochondrial genome of P. littoralis exhibits both alpha-proteobacterial characteristics and evidences of the independent integration of several exogenous DNA fragments.
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PMID:The complete sequence of a brown algal mitochondrial genome, the ectocarpale Pylaiella littoralis (L.) Kjellm. 1147 79

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a dopaminergic neurotoxin which inhibits mitochondrial complex I. 3-Nitropropionic acid (3-NPA) inhibits mitochondrial complex II and produces specific striatal lesions. In order to produce a combined striatal neuronal and dopaminergic afferent lesion, we administered both toxins simultaneously to the mouse. The combination brought about a lesion in the striatum that was not simply additive of the two combined toxins. Intriguingly, a group of striatal neurons became immunoreactive to tyrosine hydroxylase after day 1. Some of them were clearly visible up to the dendritic details. Immuno-electron microscopy indicated that the tyrosine hydroxylase-positive striatal neurons contained densely immunoreactive polyribosomes. Reverse transcriptase-polymerase chain reaction analysis indicated the up-regulation of tyrosine hydroxylase mRNA in the treated striatum. These neurons were also immunoreactive to aromatic L-amino acid decarboxylase.We conclude that the combined administration of MPTP and 3-NPA caused a more profound damage to the nigro-striatal dopaminergic system, and thus some striatal neurons capable of up-regulating tyrosine hydroxylase were induced to produce dopamine, probably to compensate for the dopamine depletion.
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PMID:Neuronal ectopic expression of tyrosine hydroxylase in the mouse striatum by combined administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 3-nitropropionic acid. 1173 97

The Escherichia coli ndh gene encodes NADH dehydrogenase II, a primary dehydrogenase used during aerobic and nitrate respiration. The anaerobic transcription factor FNR represses ndh expression by binding at two sites centred at -94.5 and -50.5. In vivo transcription studies using promoter fusions with 5' deletions confirmed that both FNR sites are required for maximum repression under anaerobic conditions. The histone-like protein Fis binds to three sites [centred at -123 (Fis I), -72, (Fis II) and +51 (Fis III)] in the ndh promoter. Using ndh : : lacZ promoter fusions carrying 5' deletions, or replacement mutations it is shown that Fis III is a repressing site and that Fis I and II are activating sites, with the greatest contribution from Fis II. Deletion of the C-terminal domain of the RNA polymerase alpha-subunit abolished Fis-mediated activation of ndh expression, suggesting that ndh has a Class I Fis-activated promoter. In accordance with the established pattern of Fis synthesis, ndh transcription was greatest during exponential growth. Thus, it is suggested that Fis enhances ndh expression during periods of rapid growth, by acting as a Class I activator, and that the binding of tandem FNR dimers represses ndh expression by preventing interaction of the RNA polymerase alpha-subunit with DNA and Fis.
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PMID:Regulation of ndh expression in Escherichia coli by Fis. 1476 19

Tirandamycin inhibits respiration and phosphorylation in rat liver mitochondria. An investigation of individual reaction sequences occurring within the respiratory chain showed that the antibiotic stimulates reduced nicotinamide adenine dinucleotide (NADH)- and succinate-linked coenzyme Q reductase. NADH-linked reduction of tetrazolium salts remains unaffected by tirandamycin. Succinotetrazolium salt reductase is inhibited significantly. Reduction of cytochrome c by succinate is blocked by the antibiotic; NADH-cytochrome c reductase is inhibited but not completely blocked. Cytochrome c oxidase remains unaffected. Mitochondrial difference spectra prepared in the presence of tirandamycin indicate that the reduction of cytochrome b is not impaired but no reduction of cytochromes c or a is apparent. These results indicate that tirandamycin interferes with the respiratory chain at a point beyond the cytochrome b and prior to the cytochrome c reduction site. Tirandamycin acts also as a potent inhibitor of ribonucleic acid polymerase as discussed in the foregoing paper.
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PMID:Tirandamycin: inhibition of oxidative phosphorylation in rat liver mitochondria. 1655 5

Human tuberculosis is still one of the most frequent causes of death worldwide. Despite the implementation of therapeutic regimes combining four drugs, the rise of resistant and multidrug-resistant Mycobacterium tuberculosis strains has compromised their efficacy. Two of the most effective anti-tubercular drugs in use, rifampicin and isoniazid, have been closely studied due to their therapeutic importance. These studies have led to the identification of the genes involved in resistance mechanisms and of those encoding the molecular targets for these drugs. Rifampicin is an inhibitor of the beta-subunit of the RNA polymerase of prokaryotes, including M. tuberculosis. Resistance to rifampicin is mediated by mutations clustered in a small region of the rpoB gene. A fraction of resistant strains showed no mutations in rpoB, suggesting that other mechanisms of resistance, possibly efflux pumps, may exist. Isoniazid is a pro-drug activated by KatG, a catalase-peroxidase. Mutations in katG, the most commonly found in M. tuberculosis clinical isolates, give high levels of resistance. In spite of this, the molecular target for isoniazid is InhA, an enoyl-ACP-reductase involved in the biosynthesis of mycolic acids. Other mutations causing resistance to isoniazid have been mapped to ndh, a gene encoding the NADH dehydrogenase.
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PMID:[Mechanisms of action of and resistance to rifampicin and isoniazid in Mycobacterium tuberculosis: new information on old friends]. 1703 59

The Zic family of zinc finger proteins is essential for animal development, as demonstrated by the holoprosencephaly caused by mammalian Zic2 mutation. To determine the molecular mechanism of Zic-mediated developmental control, we characterized two types of high molecular weight complexes, including Zic2. Complex I was composed of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), Ku70/80, and poly(ADP-ribose) polymerase; complex II contained Ku70/80 and RNA helicase A; all the components interacted directly with Zic2 protein. Immunoprecipitation, subnuclear localization, and in vitro phosphorylation analyses revealed that the DNA-PKcs in complex I played an essential role in the assembly of complex II. Stepwise exchange from complex I to complex II depended on phosphorylation of Zic2 by DNA-PK and poly-(ADP-ribose) polymerase. Phosphorylated Zic2 protein made a stable complex with RNA helicase A, and complex II could interact with RNA polymerase II. Phosphorylation-dependent transformation of Zic2-containing molecular complexes may occur in transcriptional regulation.
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PMID:ZIC2-dependent transcriptional regulation is mediated by DNA-dependent protein kinase, poly(ADP-ribose) polymerase, and RNA helicase A. 1725 Nov 88

The strains of Thermus thermophilus that contain the nitrate respiration conjugative element (NCE) replace their aerobic respiratory chain by an anaerobic counterpart made of the Nrc-NADH dehydrogenase and the Nar-nitrate reductase in response to nitrate and oxygen depletion. This replacement depends on DnrS and DnrT, two homologues to sensory transcription factors encoded in a bicistronic operon by the NCE. DnrS is an oxygen-sensitive protein required in vivo to activate transcription on its own dnr promoter and on that of the nar operon, but not required for the expression of the nrc operon. In contrast, DnrT is required for the transcription of these three operons and also for the repression of nqo, the operon that encodes the major respiratory NADH dehydrogenase expressed during aerobic growth. Thermophilic in vitro assays revealed that low DnrT concentrations allows the recruitment of the T. thermophilus RNA polymerase sigma(A) holoenzyme to the nrc promoter and its transcription, whereas higher DnrT concentrations are required to repress transcription on the nqo promoter. In conclusion, our data show a complex autoinducible mechanism by which DnrT functions as the transcriptional switch that allows the NCE to take the control of the respiratory metabolism of its host during adaptation to anaerobic growth.
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PMID:Control of the respiratory metabolism of Thermus thermophilus by the nitrate respiration conjugative element NCE. 1746 13

A bush-type plant was selected from tropical pumpkin 'cga' (Cucurbita moschata Duchesne) in order to study the vine development in C. moschata. In this study, a novel gene encoding NADH dehydrogenase was isolated from the vine line (cgaV) of C. moschata, that was not expressed in the near isogenic bush line (cgaBu). This gene, designated as CmV1 (C. moschata vine 1), was 545 bp in length and was composed of a 477 bp open reading frame, which had 99% nucleotide similarity to the chloroplast ndhJ gene for NADH dehydrogenase subunit J from Brassica oleracea. The deduced amino acid sequence of CmV1 had 99% similarity to NADH dehydrogenase subunit J from Arabidopsis and had 98% similarity to NADH dehydrogenase subunit from Barbarea verna. Analysis of the basic characteristics of the CmV1 protein revealed that it has one Respiratory chain NADH dehydrogenase 30 kD subunit signature, three N-myristoylation sites, one Casein kinase II phosphorylation site, and one Protein kinase C phosphorylation site. Reverse transcriptase-PCR analysis showed that CmV1 was expressed at a high level in the internodes and hypocotyls and was expressed stronger in elongating internodes than in fully expanded internodes. In conclusion, results obtained in the present study suggest that CmV1 gene might play important roles in vine elongation of tropical pumpkin.
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PMID:Molecular cloning and expression of a bush related CmV1 gene in tropical pumpkin. 1930 73


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