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:1.6.5.3 (complex I)
8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A critical step in the assembly of bacteriophage lambda is the excision of a single genome from a concatemeric DNA precursor and insertion of genomic DNA into an empty viral capsid. DNA packaging is mediated by the lambda proteins gpNu1 and gpA, which form an enzyme complex known as terminase. Initiation of the packaging process requires assembly of the terminase subunits onto cos, the lambda DNA packaging sequence, and nicking of the duplex, thus forming the 12-base-pair "sticky" ends of the mature genome. We have utilized gel-retardation techniques to examine the interaction of gpNu1, gpA, and terminase holoenzyme with DNA. Our data demonstrate that gpNu1 interacts specifically with cos-containing DNA, forming three gel-retarded complexes. Similarly, the larger gpA subunit binds to DNA, forming two complexes; however, this subunit forms similar complexes with DNA substrates of random sequence. All of the nucleoprotein complexes examined are disrupted by elevated concentrations of NaCl and we suggest that altered DNA binding is responsible for the extreme salt sensitivity of the endonuclease activity of the enzyme [Tomka, M. A., & Catalano, C. E. (1993) J. Biol. Chem. 268, 3056-3065]. DNA binding by each subunit is strongly affected by the presence of the other, with 10- and 3-fold increases in the affinity of gpNu1 and gpA, respectively, for DNA. Moreover, our data suggest that the terminase subunits interact in solution prior to DNA binding. Finally, we provide evidence that complex I, the first stable intermediate in the packaging pathway, is composed of the mature left genome end bound to the terminase subunits and demonstrate that dissociation of the complex is quite slow (t1/2 > 8 h). The significance of these data with respect to terminase-mediated genome packaging is discussed.
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PMID:Assembly of a nucleoprotein complex required for DNA packaging by bacteriophage lambda. 906 1

The in vivo and in vitro bindings of radiolabeled rotenoids to mitochondrial complex I of rat striatum were examined after unilateral intrastriatal injections of quinolinic acid or 1-methyl-4-phenylpyridinium salt (MPP+). Quinolinic acid produced significant, similar losses of in vivo binding of [11C]dihydrorotenol ([11C]DHROL: 40%) and in vitro binding of [3H]dihydrorotenone ([3H]DHR: 53%) in the injected striatal at 13 days after the injection of neurotoxin. MPP+ reduced in vivo binding of [11C]DHROL up to-55%) as measured 1.5 to 6 h after its administration. Reductions of in vivo [11C]DHROL binding after either quinolinic acid or MPP+ injections did not correlate with changes in striatal blood flow as measured with [14C]iodoantipyrine. These results are consistent with losses of complex I binding sites for radiolabeled rotenoids, produced using cell death (quinolinic acid) or direct competition for the binding site (MPP+). Appropriately radiolabeled rotenoids may be useful for in vivo imaging studies of changes of complex I in neurodegenerative diseases.
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PMID:Intrastriatal neurotoxin injections reduce in vitro and in vivo binding of radiolabeled rotenoids to mitochondrial complex I. 911 99

The proton-pumping NADH:ubiquinone oxidoreductase of Escherichia coli is composed of 14 different subunits and contains one FMN and up to nine iron-sulfur clusters as prosthetic groups. By use of salt treatment, the complex can be split into an NADH dehydrogenase fragment, a connecting fragment and a membrane fragment. The water-soluble NADH dehydrogenase fragment has a molecular mass of approximately 170,000 Da and consists of the subunits NuoE, F, and G. The fragment harbors the FMN and probably six iron-sulfur clusters, four of them being observable by EPR spectroscopy. Here, we report that the fully assembled fragment can be overproduced in E. coli when the genes nuoE, F, and G were simultaneously overexpressed with the genes nuoB, C, and D. Furthermore, riboflavin, sodium sulfide, and ferric ammonium citrate have to be added to the culture medium. The fragment was purified from the cytoplasm by means of ammonium sulfate fractionation and chromatographic steps. The preparation contains one noncovalently bound FMN per molecule. Two binuclear (N1b and N1c) and two tetranuclear (N3 and N4) iron-sulfur clusters were detected by EPR in the NADH reduced preparation with spectral characteristics identical with those of the corresponding clusters in complex I. The preparation fulfills all prerequisites for crystallization of the fragment.
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PMID:Characterization of the overproduced NADH dehydrogenase fragment of the NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli. 948 11

NADH coenzyme Q reductase (EC 1.6.5.3) has been suggested in the literature to be inactivated by ischaemia. In the present study, NADH coenzyme Q reductase activity was localized in unfixed cryostat sections of ischaemic rat livers and quantified using image analysis. In vitro ischaemia was induced by storage of rat liver fragments for 30, 60, and 120 min at 37 degrees C. In vivo ischaemia was provoked by clamping the afferent vessels of median and left lateral liver lobes for 60 min followed by 30, 60 and 180 min of reperfusion. NADH coenzyme Q reductase activity was demonstrated with the tetrazolium salt method in the presence of polyvinyl alcohol. Final reaction product was found in liver parenchymal cells and its distribution was homogeneous within liver lobules. Only low amounts of final reaction product were formed when the incubation was performed in the absence of the substrate NADH. A non-linear relation was found between the absorbance and incubation time when the reaction was performed in the presence of NADH. Therefore, the initial velocity was taken as the true rate of enzyme activity. A linear relationship was found for the initial velocity and section thickness up to 6 microm followed by a levelling off. Electron microscopically, NADH coenzyme Q reductase activity was localized at the outer and inner membranes of mitochondria. In vitro ischaemia up to 120 min did not affect NADH coenzyme Q reductase activity. At 30 min reperfusion after in vivo ischaemia for 60 min enzyme activity was slightly decreased in certain foci which also showed diminished lactate dehydrogenase activity. A further decrease of enzyme activities in foci was observed at 180 min reperfusion after ischaemia. It is concluded that NADH coenzyme Q reductase activity is not sensitive to ischaemia. Furthermore, it is likely that the enzyme leaks from liver parenchymal cells into the circulation during reperfusion after ischaemia.
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PMID:Effects of ischaemia and reperfusion on NADH coenzyme Q reductase activity in rat liver. 1057 30

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

Electron microscopy has demonstrated the unusual L-shaped structure of the respiratory complex I consisting of two arms, which are arranged perpendicular to each other. We found that the Escherichia coli complex I has an additional stable conformation, with the two arms arranged side by side, resulting in a horseshoe-shaped structure. The structure of both conformations was determined by means of electron microscopy of gold thioglucose-stained single particles. They were distinguished from each other by titration of the complex with polyethylene glycol and by means of analytical ultracentrifugation. The transition between the two conformations is induced by the ionic strength of the buffer and is reversible. Only the horseshoe-shaped complex I exhibits enzyme activity in detergent solution, which is abolished by the addition of salt. Therefore, it is proposed that this structure is the native conformation of the complex in the membrane.
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PMID:A novel, enzymatically active conformation of the Escherichia coli NADH:ubiquinone oxidoreductase (complex I). 1188 Mar 70

The development of crop plants with increased salt tolerance necessitates the study of naturally salt-tolerant eukaryotic species. We studied the bio-synthesis of glycerol as a compatible solute in the halophilic eukaryotic microorganism, black yeast Hortaea werneckii. A restriction fragment-differential display technique was used to investigate the transcriptome of the organism. Eight differentially expressed genes were identified in response to growth at different salinities. Although the putative functions of their products, P-type ATPase, ubiquinone reductase, aconitase, RNA helicase, Asn-tRNA ligase, isoamyl alcohol oxidase, and phosphatidylinositol-3-kinase, are not intimately related within the cellular machinery, the results presented here are sufficient to propose a model which describes how H. werneckii adapts to extremely high salinities. Some of these mechanisms of adaptation to raised environmental salinity are similar to those in other salt-sensitive species, e.g. glycerol accumulation, there also appear to be novel mechanisms present such as the use of different energy production mechanisms and post-transcriptional regulation of gene expression. Our results have also provided new data on two genes from two other fungal species, the Neurospora crassa B1D1.130 gene and the Aspergillus ustus amdS-A gene.
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PMID:Cellular responses to environmental salinity in the halophilic black yeast Hortaea werneckii. 1213 14

Some cDNA sequences of subunit V (PsaG) of Photosystem I (PS I) reaction center in several species have been cloned, and PsaG has been characterized as a connection of light-harvesting complex I (LHC I) protein to photosystem reaction center. Here we present the isolation and characterization of its salt-induced homologue (DsPsaG) in Dunaliella salina. Sequence alignment shows that there is a significant similarity between the deduced amino acid sequence of DsPsaG and PsaG protein in Chlamydomonas reinhardtii, as well as between the deduced amino acid sequence of DsPsaG and other PsaG gene products. The differential expression of DsPsaG at different time points after salt stress reveals that DsPsaG mRNA was absent without salt stress and was indeed salt-induced. Its expression reached its maximum level 5 days after stress. Our study suggests that DsPsaG should be a compensation of PsaG in D. salina when the alga was in a hyperosmotic condition. It can also be useful to effectively transfer light energy from LHC I to PS I reaction center.
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PMID:Isolation and characterization of a salt-induced PsaG of photosystem I in Dunaliella salina. 1239 29

Germanium complexes (IV) with succinic (H2Suc), oxyethyliminodiacetic (H2Oeida) and iminodisuccinic (H4Ids) acids as well as homo- and heteroligand germanium complexes (IV)--products of interaction of triammonium salt of oxyethylidendiphosphonic acid ((NH4)3HL) and oxyacids: tartaric (H4Tart), citric (H4Citr), trioxyglutaric (H4Toglut) acids have been synthesized. Composition of the obtained complexes: [Ge(OH)2(NaSuc)2].2H2O (I); [Ge(OH) (Oeida).H2O].H2O (II); [Ge(OH)2(NaHIds)2] (III); [Ge(OH)2(NH4)3HL) (H2Tart)] (IV); [Ge(OH)2(NH4)3HL) (H2Citr)] (V); [Ge(OH)2(NH4)3HL) (H2Toglut)] (VI); [Ge(OH)2((NH4)2HL)2] (VII); [Ge (OH)2((NH4)2HL)2] (VII); [Ge(OH)2 (H2O)2(NH4) HL] (VIII) has been determined. The capability of the synthesized compounds has been studied to affect synthesis and activity of the following enzymes: collagenase, alpha-N-acetylgalactosaminidase (alpha-GalNAc-ase) and alpha-galactosidase (alpha-Gal-ase). It has been established that the complexes II-VIII activate biosynthesis of alpha-Gal-ase and alpha-GalNAc-ase, while germanium dioxide (IX) and complex I possess considerable inhibiting effect on synthesis of the above enzymes. It has been also established that all the compounds except for IV increased the activity of both alpha-Gal-ase and alpha-GalNAc-ase. All the considered complexes demonstrated similar reaction with respect to collagenase: they inhibited both synthesis and activity.
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PMID:[Effect of coordinational germanium compounds on enzyme synthesis and activity]. 1243 65

Complex I is one of the respiratory chain enzymes related to NADH dehydrogenase and is an encoded gene product derived from both nuclear and mitochondrial genomes. Transcription levels of ND1 (mitochondrial) and 51 kDa (nuclear) subunits of complex I in the postnatal development of the intrinsic muscle in rat tongues were determined by Northern blot analysis. Enzyme activity levels were determined by NADH staining with tetrazolum salt, and oxygen consumption of NADH-O2 oxidoreductase activity using a Clark-type electrode. The detailed structure of the mitochondria was observed using electron microscopy. The cross-sectional area of the mitochondria gradually increased during postnatal development, and the cristae also became complex, despite the length of mitochondria in muscle fibre being constant. The mitochondria density increased from birth to 15 days of age, and declined slightly afterwards. This pattern of density resembled that of NADH-O2 oxidoreductase activity. The level of mRNA for ND1 through Northern blot analysis gradually increased from birth to 15 days of age and was highest at 21 days. For 51 kDa, the level was highest at 0 days and fell thereafter to a constant low. This suggests that the production of NADH dehydrogenase is limited by 51 kDa of Complex I derived from nuclear genomes rather than by the increase in mitochondria and composition of muscle fibre types due to changes in feeding behaviour.
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PMID:NADH-O2 oxidoreductase activity and mRNA expression of complex I (51 kDa, ND1) in postnatal intrinsic muscle of rat tongue. 1264 70


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