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:1.6.99.3 (diaphorase)
5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Starvation for 3 days produces a decrease in methaemoglobin-reductase and glutathione-reductase activities, but it does not alter the glucose 6-phosphate-dehydrogenase activity of the rat erythrocyte. 2. The feeding of a protein-free diet for 11 days causes greater changes in the first two enzymes and also a diminution of the third. Under this experimental condition slight decreases in protein and haemoglobin contents were noted. 3. The experimental animals did not show methaemoglobinaemia, probably because the activity of methaemoglobin diaphorase is preserved. 4. The GSH content was not affected but the stability of the tripeptide in the presence of an oxidizing agent was diminished.
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PMID:Studies on the oxidation-reduction systems of the erythrocyte. 437 99

NADH dehydrogenase is the first component of the respiratory chain. It transfers electrons from NADH to ubiquinone and concomitantly establishes a proton motive force across the membrane. Salmonella typhimurium mutants defective in this enzyme were isolated in a screen for strains with increased expression of beta-galactosidase from a hemA-lacZ protein fusion. This unexpected phenotype results from stabilization of the hybrid protein during carbon starvation and is apparently due to an energy requirement for proteolytic attack. Sequence analysis of DNA fragments cloned from an insertion mutant indicates that S. typhimurium has a large cluster of genes encoding the energy-conserving NADH dehydrogenase, similar to one recently described in Paracoccus denitrificans. These findings establish the potential for genetic analysis of a complex enzyme whose function, especially in proton efflux, is poorly understood.
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PMID:Mutants defective in the energy-conserving NADH dehydrogenase of Salmonella typhimurium identified by a decrease in energy-dependent proteolysis after carbon starvation. 823 29

Transposon insertions that stabilize the beta-galactosidase activity of a HemA-LacZ hybrid protein following carbon starvation were mapped to the atp operon of Salmonella typhimurium. This effect is similar to that seen with nuo mutants defective in the energy-conserving type I NADH dehydrogenase. Insertions in several other genes, including such highly pleiotropic mutants as rpoS, polA, and hfq, were isolated with the same phenotypic screen, but they do not affect the beta-galactosidase activity of HemA-LacZ. All of these mutants act indirectly to alter the colony color of many different fusion strains on indicator plates.
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PMID:Stabilization of a HemA-LacZ hybrid protein against proteolysis during carbon starvation in atp mutants of Salmonella typhimurium. 863 58

The secretion of numerous proteins during vegetative growth of Myxococcus xanthus, and the multicellular development cycle induced upon starvation of these bacteria, are partially interrelated in so far as mutants impaired in extracellular protein production are unable to undergo development. We have cloned and sequenced a gene in which a Tn5 insertion leads to a decrease in the production of most, if not all, extracellular proteins, and prevents development and sporulation. The deduced protein is homologous to the putative ubiquinone-binding subunit of bacterial and mitochondrial NADH:ubiquinone oxidoreductases (complex I). This is the first example of the presence of this complex in a bacterium from subclass delta of the proteobacteria. This gene is expressed during growth and during early development. As its disruption by Tn5 does not impair growth of the mutant strain, we assume the presence of a second alternative NADH oxidoreductase, and suggest that the phenotypic alterations caused by the mutation are due to a decrease in the proton-motive force.
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PMID:A gene involved in both protein secretion during growth and starvation-induced development encodes a subunit of the NADH:ubiquinone oxidoreductase in Myxococcus xanthus. 907 40

ND4 is a mitochondrially encoded component of NADH dehydrogenase (Complex I) of the respiratory chain. A cDNA encoding a fusion protein comprised of the N-terminus of GAL10 of Saccharomyces cerevisiae and an N-terminally truncated form of human ND4 was isolated by its ability to functionally complement the thymidine transport deficiency of S. cerevisiae grown under conditions of thymidylate starvation. Epitope-tagged GAL10-ND4 was shown by immunological methods to be present in the plasma membranes of yeast expressing the GAL10-ND4 encoding cDNA. The ability of the GAL10-ND4 fusion protein to induce uptake of thymidine raises the possibility that native ND4, which is predicted to have 12 transmembrane domains, may function as a transporter or channel in the mitochondrial inner membrane.
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PMID:Functional complementation of a membrane transport deficiency in Saccharomyces cerevisiae by recombinant ND4 fusion protein. 932 73

An apoptosis-resistant mutant (VC-33) was selected from HL-60 by alternating exposure to camptothecin and etoposide. VC-33 cells demonstrated resistance to apoptosis as induced not only by camptothecin and etoposide but by a variety of other agents as well, including 1-beta-D-arabinofuranosylcytosine, hydroxyurea, calcium ionophore (A23187), cycloheximide, and UV irradiation. In an effort to identify the mechanism of such apoptosis resistance, a mRNA differential display analysis was used. Among a total of 12 bands with reduced expression in VC-33 cells, 1 cDNA clone was isolated that was hybridized to the wild-type transcript but not to the VC-33 transcript on Northern blotting. Partial sequence of this gene revealed 98% homology to mitochondrial NADH dehydrogenase subunit 5. When cell growth and intracellular ATP levels under glucose starvation were measured, VC-33 cells were found to be more sensitive than wild-type cells. Thus, NADH dehydrogenase deficiency may contribute, at least in part, to the mechanism of resistance to apoptosis in VC-33 cells.
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PMID:NADH dehydrogenase deficiency in an apoptosis-resistant mutant isolated from a human HL-60 leukemia cell line. 939 42

Using synchronized Dictyostelium discoideum Ax-2 cells and the differential display method, a mitochondrial gene cluster (referred to as differentiation-associated gene 3; dia3) was isolated as one of the genes expressed specifically during the transition of Ax-2 cells from growth to differentiation. The dia3 gene encodes for a mitochondrial protein cluster (NADH dehydrogenase (NAD) subunit 11, 5, ribosomal protein S4 (RPS4), RPS2, and NAD4L). Northern blot analysis using nonsynchronized Ax-2 cells has shown that the dia3 RNA of about 8 kb is scarcely expressed during the vegetative growth phase, and the maximal expression was attained at 2 h after starvation. To analyze the gene function of dia3, we tried inactivation of rps4 by means of homologous recombination and obtained several transformed clones showing mitochondrial DNA heteroplasmy. The transformed cells grew normally in nutrient medium, but their development after starvation was greatly impaired, thus resulting in the failure of many cells to differentiate. In this connection, the cAMP receptor 1 (car1) expression, which is one of the earliest markers of differentiation, was found to be markedly reduced in the rps4-inactivated cells.
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PMID:Transient expression of a mitochondrial gene cluster including rps4 is essential for the phase-shift of Dictyostelium cells from growth to differentiation. 1057 Apr 66

Cytosolic redox balance has to be maintained in order to allow an enduring cellular metabolism. In other words, NADH generated in the cytosol has to be re-oxidized back to NAD(+). Aerobically this can be done by respiratory oxidation of cytosolic NADH. However, NADH is unable to cross the mitochondrial inner membrane and mechanisms are required for conveying cytosolic NADH to the mitochondrial electron transport chain. At least two such systems have proved to be functional in S. cerevisiae, the external NADH dehydrogenase (Luttik et al., 1998; Small and McAlister-Henn, 1998) and the G3P shuttle (Larsson et al., 1998). The aim of this investigation was to study the regulation and performance of these two systems in a wild-type strain of S. cerevisiae using aerobic glucose- and nitrogen-limited chemostat cultures. The rate of cytosolic NADH formation was calculated and as expected there was a continuous increase with increasing dilution rate. However, measurements of enzyme activities and respiratory activity on isolated mitochondria revealed a diminishing capacity at elevated dilution rates for both the external NADH dehydrogenase and the G3P shuttle. This suggests that adjustment of in vivo activities of these systems to proper levels is not achieved by changes in amount of protein but rather by, for example, activation/inhibition of existing enzymes. Adenine nucleotides are well-known allosteric regulators and both the external NADH and the G3P shuttle were sensitive to inhibition by ATP. The most severe inhibition was probably on the G3P shuttle, since one of its member proteins, Gpdp, turned out to be exceptionally sensitive to ATP. The external NADH dehydrogenase is suggested as the main system employed for oxidation of cytosolic NADH. The G3P shuttle is proposed to be of some importance at low growth rates and perhaps its real significance is only expressed during starvation conditions.
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PMID:Cytosolic redox metabolism in aerobic chemostat cultures of Saccharomyces cerevisiae. 1132 72

Survival, electron transport system (ETS) activity and the activity of NADH and succinate dehydrogenase of Escherichia coli ML30 were studied under starvation stress at different temperatures in a filtered-autoclaved lake water microcosm. ETS activity in E. coli declined rapidly at 30 degrees C but more slowly at 4 degrees and 15 degrees C over a 20 d starvation period. The decrease in ETS activity in E. coli only started after 6 d of incubation at 4 degrees C and 15 degrees C. Viability of E. coli, as determined by plate counts, declined faster at 37 degrees C than at the other temperatures and remained highest at 4 degrees C in filtered-autoclaved lake water. There was also a significant cell size reduction at 37 degrees C in filtered-autoclaved lake water but not at 4 degrees C. ETS activity after up to 16 d of starvation increased after the addition of nutrient broth to the filtered-autoclaved lake water at 15 degrees C and 30 degrees C suggesting that cells were still able to respond to nutrients, even after prolonged starvation. The response to the addition of nutrient broth, however, declined with the length of the starvation period. The activity of both succinate and NADH dehydrogenase declined over a 13 d starvation period. The loss of activity was fastest at 37 degrees C compared to lower incubation temperatures but even at 4 degrees C, a significant proportion of the activity was lost over the 13 d period.
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PMID:Relationship between respiratory enzymes and survival of Escherichia coli under starvation stress in lake water. 1245 93

Combined transcriptome and proteome analysis was carried out to understand metabolic and physiological changes of Escherichia coli during the high cell density cultivation (HCDC). The expression of genes of TCA cycle enzymes, NADH dehydrogenase and ATPase, was up-regulated during the exponential fed-batch period and was down-regulated afterward. However, expression of most of the genes involved in glycolysis and pentose phosphate pathway was up-regulated at the stationary phase. The expression of most of amino acid biosynthesis genes was down-regulated as cell density increased, which seems to be the major reason for the reduced specific productivity of recombinant proteins during HCDC. The expression of chaperone genes increased with cell density, suggesting that the high cell density condition itself can be stressful to the cells. Severe competition for oxygen at high cell density seemed to make cells use cytochrome bd, which is less efficient but has a high oxygen affinity than cytochrome bo(3). Population cell density itself strongly affected the expression of porin protein genes, especially ompF, and hence the permeability of the outer membrane. Expression of phosphate starvation genes was most strongly up-regulated toward the end of cultivation. It was also found that sigma(E) (rpoE) plays a more important role than sigma(S) (rpoS) at the stationary phase of HCDC. These findings should be invaluable in designing metabolic engineering and fermentation strategies for the production of recombinant proteins and metabolites by HCDC of E. coli.
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PMID:Combined transcriptome and proteome analysis of Escherichia coli during high cell density culture. 1255 8


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