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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

T cells move randomly ("random-walk"), a characteristic thought to be integral to their function. Using migration assays and time-lapse microscopy, we found that CD8+ T cells lacking the lymph node homing receptors CCR7 and CD62L migrate more efficiently in transwell assays, and that these same cells are characterized by a high frequency of cells exhibiting random crawling activity under culture conditions mimicking the interstitial/extravascular milieu, but not when examined on endothelial cells. To assess the energy efficiency of cells crawling at a high frequency, we measured mRNA expression of genes key to mitochondrial energy metabolism (peroxisome proliferator-activated receptor gamma coactivator 1beta [PGC-1beta], estrogen-related receptor alpha [ERRalpha], cytochrome C, ATP synthase, and the uncoupling proteins [UCPs] UCP-2 and -3), quantified ATP contents, and performed calorimetric analyses. Together these assays indicated a high energy efficiency of the high crawling frequency CD8+ T-cell population, and identified differentially regulated heat production among nonlymphoid versus lymphoid homing CD8+ T cells.
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PMID:A high-mobility, low-cost phenotype defines human effector-memory CD8+ T cells. 1884 92

In addition to providing the earliest surface images of a native photosynthetic membrane at submolecular resolution, examination of the intracytoplasmic membrane (ICM) of purple bacteria by atomic force microscopy (AFM) has revealed a wide diversity of species-dependent arrangements of closely packed light-harvesting (LH) antennae, capable of fulfilling the basic requirements for efficient collection, transmission, and trapping of radiant energy. A highly organized architecture was observed with fused preparations of the pseudocrystalline ICM of Blastochloris viridis, consiting of hexagonally packed monomeric reaction center light-harvesting 1 (RC-LH1) core complexes. Among strains which also form a peripheral LH2 antenna, images of ICM patches from Rhodobacter sphaeroides exhibited well-ordered, interconnected networks of dimeric RC-LH1 core complexes intercalated by rows of LH2, coexisting with LH2-only domains. Other peripheral antenna-containing species, notably Rhodospirillum photometricum and Rhodopseudomonas palustris, showed a less regular organization, with mixed regions of LH2 and RC-LH1 cores, intermingled with large, paracrystalline domains. The ATP synthase and cytochrome bc(1) complex were not observed in any of these topographs and are thought to be localized in the adjacent cytoplasmic membrane or in inaccessible ICM regions separated from the flat regions imaged by AFM. The AFM images have served as a basis for atomic-resolution modeling of the ICM vesicle surface, as well as forces driving segregation of photosynthetic complexes into distinct domains. Docking of atomic-resolution molecular structures into AFM topographs of Rsp. photometricum membranes generated precise in situ structural models of the core complex surrounded by LH2 rings and a region of tightly packed LH2 complexes. A similar approach has generated a model of the highly curved LH2-only membranes of Rba. sphaeroides which predicts that sufficient space exists between LH2 complexes for quinones to diffuse freely. Measurement of the intercomplex distances between adjacent LH2 rings of Phaeospirillum molischianum has permitted the first calculation of the separation of bacteriochlorophyll a molecules in the native ICM. A recent AFM analysis of the organization of green plant photosystem II (PSII) in grana thylakoids revealed the protruding oxygen-evolving complex, crowded together in parallel alignment at three distinct levels of stacked membranes over the lumenal surface. The results also confirmed that PSII-LHCII supercomplexes are displaced relative to one another in opposing grana membranes.
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PMID:Atomic force microscopy studies of native photosynthetic membranes. 1926 34

Effects of treatment with DHEA (0.2 or 1.0 mg/kg body weight for 7 days) on oxidative energy metabolism of rat liver mitochondria from old (18-24 month old) and young (8-10 weeks old) male albino rats belonging to Charles-Foster strain were examined. Treatment with 1.0 mg DHEA resulted in increased body weights of the young rats without change in the liver weight. In the old animals the liver weight increased progressively with increasing dose of DHEA without affecting body weight. The state 3 respiration rates in liver mitochondria from old animals were, in general, lower than those in the young rats. The state 3 and state 4 respiration rates increased following DHEA treatment in dose-dependent manner bringing them close to values for young animals or beyond that with the effect being more pronounced at 1.0 mg dose. Treatment with DHEA also stimulated state 3 and state 4 respiration rates in young rats in dose-dependent manner. Contents of cytochrome aa(3), b and c + c(1) increased significantly in old animals in dose-dependent manner. In the young rats the lower dose (0.2 mg) of DHEA was more effective in bringing about a maximum increase in the contents of the cytochromes; the effect declined at the higher dose (1.0 mg). DHEA treatment also stimulated the mitochondrial ATPase activity in the old as well as in the young rats. The dehydrogenases activities were considerably low in the old rats compared to the values for the young animals. Treatment with DHEA stimulated dehydrogenases activities in old rats in dose-dependent manner bringing them close to values for the young animals or beyond. Treatment with lower dose (0.2 mg) of DHEA maximally stimulated dehydrogenases activities in young animals.
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PMID:Stimulation of oxidative energy metabolism in liver mitochondria from old and young rats by treatment with dehydroepiandrosterone (DHEA). A comparative study. 1942 29

Two splice variants of the Marek's disease virus phosphorylated polypeptide (pp)38 were previously identified in the quail cell line QTP32 expressing pp38 under the control of an inducible promoter. We developed QT35-derived cell lines expressing these splice variants or full length pp38 with the splice acceptor sites mutated to further elucidate the role of pp38. Only induction of full length pp38 resulted in an increase in mitochondrial succinate dehydrogenase activity compared to non-induced cells. Transcript copy numbers of cytochrome C oxidase subunit I and ATP synthase were reduced in induced cells. The ATP content of isolated mitochondria from induced cells was greatly reduced compared to those of non-induced cells. Mitochondrial and pp38 staining suggests that there is no direct interaction between pp38 and the mitochondria. Mitochondrial transcripts were also reduced in DF-1 cells expressing full length pp38 and in MDV-infected chick kidney cells indicating that this effect occurs independent of other viral genes and after in vitro infection with MDV.
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PMID:Marek's disease virus phosphorylated polypeptide pp38 alters transcription rates of mitochondrial electron transport and oxidative phosphorylation genes. 1947 43

In all domains of life Oxa1p-like proteins are involved in membrane protein biogenesis. Bacillus subtilis, a model organism for gram-positive bacteria, contains two Oxa1p homologs: SpoIIIJ and YqjG. These molecules appear to be mutually exchangeable, although SpoIIIJ is specifically required for spore formation. SpoIIIJ and YqjG have been implicated in a posttranslocational stage of protein secretion. Here we show that the expression of either spoIIIJ or yqjG functionally compensates for the defects in membrane insertion due to YidC depletion in Escherichia coli. Both SpoIIIJ and YqjG complement the function of YidC in SecYEG-dependent and -independent membrane insertion of subunits of the cytochrome o oxidase and F(1)F(o) ATP synthase complexes. Furthermore, SpoIIIJ and YqjG facilitate membrane insertion of F(1)F(o) ATP synthase subunit c from both E. coli and B. subtilis into inner membrane vesicles of E. coli. When isolated from B. subtilis cells, SpoIIIJ and YqjG were found to be associated with the entire F(1)F(o) ATP synthase complex, suggesting that they have a role late in the membrane assembly process. These data demonstrate that the Bacillus Oxa1p homologs have a role in membrane protein biogenesis rather than in protein secretion.
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PMID:Bacillus subtilis SpoIIIJ and YqjG function in membrane protein biogenesis. 1971 9

The problem of the resolution and reconstitution of the inner mitochondrial membrane has been approached at three levels. (1) Starting with phosphorylating submitochondrial particles, a "resolution from without" can be achieved by stripping of surface components. The most extensive resolution was recently obtained with the aid of silicotungstate. Such particles require for oxidative phosphorylation the addition of several coupling factors as well as succinate dehydrogenase. (2) Starting with submitochondrial particles that have been degraded by trypsin and urea a resolution of the inner membrane proper containing an ATPase has been achieved. These experiments show that at least five components are required for the reconstitution of an oligomycin-sensitive ATPase: a particulate component, F(1), Mg(++), phospholipids, and F(c). Morphologically, the reconstituted ATPase preparations resemble submitochondrial particles. (3) Starting with intact mitochondria individual components of the oxidation chain have been separated from each other. The following components were required for the reconstitution of succinoxidase: succinate dehydrogenase, cytochrome b\, cytochrome c(1), cytochrome c, cytochrome oxidase, phospholipids and Q(10). The reconstituted complex had properties similar to those of phosphorylating submitochondrial particles; i.e., the oxidation of succinate by molecular oxygen was highly sensitive to antimycin.
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PMID:Resolution and reconstitution of a Mammalian membrane. 1987 54

Blue and colorless native gel electrophoresis in combination with LC-ESI-MS/MS are powerful tools in the analysis of protein networks in biological membranes. We used these techniques in the present study to generate a comprehensive overview on a proteome-wide scale of intracytoplasmic membrane (ICM) associated proteins in order to investigate the native supramolecular organization of Rhodobacter sphaeroides R26.1 photosynthetic apparatus. The results obtained were compared with past proteomic data, as well as with models for the topology of photosynthetic membranes as derived from previously published atomic force microscopy studies. We identified 52 proteins organized in 10 different multiprotein complexes. We were able to demonstrate the existence of different oligomeric states for the integral membrane pigment-protein complexes dedicated to bacterial photosynthesis. Specifically, we found dimers and trimers, as well as supercomplexes of light-harvesting (LH) 2 at very high molecular weights (around 10,000 kDa). We recovered the monomeric form of the photochemical reaction center (RC), as well as the monomer and dimer of the reaction center-light harvesting 1-PufX (RC-LH1-PufX) complex. Curiously, no type of LH1 complex was detected. Lastly, ATP synthase and cytochrome bc(1) complexes were only recovered in their monomeric states. Purified ICM vesicles were shown to be rich in newly discovered gene products, including three proteins with unknown functions (RSP_2125, RSP_3238, RSP_6207), a possible alkane hydroxylase and a spheroidene monooxygenase. Other multiprotein complexes were found to be localized in the ICM, including succinate dehydrogenase in trimeric form and sarcosine oxidase in two different aggregation states. These findings contribute to the growing body of evidence that the bacterial ICM is a specialized bioenergetic membrane hosting, not only photosynthesis, but many other critical activities.
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PMID:Oligomeric characterization of the photosynthetic apparatus of Rhodobacter sphaeroides R26.1 by nondenaturing electrophoresis methods. 1989 38

YidC depletion affects membrane protein insertion and leads to a defect in the growth of the Escherichia coli cell. We analyzed global changes in gene expression upon YidC depletion to determine the importance of YidC for cellular functions using a gene chip method to compare the transcriptomes of JS71 (control) and JS7131 (yidC depletion strain). Of the more than 4,300 genes identified, 163 were upregulated and 99 were downregulated upon YidC depletion, including genes which are responsible for DNA/RNA repair; energy metabolism; various transporters, proteases and chaperones; stress response; and translation and transcription functions. Real-time PCR was performed on selected genes to confirm the results. Specifically, we found upregulation of the genes encoding the energy transduction proteins F(1)F(o) ATP synthase and cytochrome bo(3) oxidase due to perturbation in assembly when YidC was depleted. We also determined that the high-level induction of the PspA stress protein under YidC depletion conditions is roughly 10-fold higher than the activation due to the addition of protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP), which dissipates the proton motive force. In addition, the gene chip data reveal the Cpx stress pathway is activated upon YidC depletion. The data show the broad physiological contribution of YidC to the bacterial cell and the considerable ramification to the cell when it is depleted.
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PMID:Global change of gene expression and cell physiology in YidC-depleted Escherichia coli. 2006 85

Mycobacteria are a group of obligate aerobes that require oxygen for growth, but paradoxically have the ability to survive and metabolize under hypoxia. The mechanisms responsible for this metabolic plasticity are unknown. Here, we report on the adaptation of Mycobacterium smegmatis to slow growth rate and hypoxia using carbon-limited continuous culture. When M. smegmatis is switched from a 4.6 h to a 69 h doubling time at a constant oxygen saturation of 50%, the cells respond through the down regulation of respiratory chain components and the F1Fo-ATP synthase, consistent with the cells lower demand for energy at a reduced growth rate. This was paralleled by an up regulation of molecular machinery that allowed more efficient energy generation (i.e. Complex I) and the use of alternative electron donors (e.g. hydrogenases and primary dehydrogenases) to maintain the flow of reducing equivalents to the electron transport chain during conditions of severe energy limitation. A hydrogenase mutant showed a 40% reduction in growth yield highlighting the importance of this enzyme in adaptation to low energy supply. Slow growing cells at 50% oxygen saturation subjected to hypoxia (0.6% oxygen saturation) responded by switching on oxygen scavenging cytochrome bd, proton-translocating cytochrome bc1-aa3 supercomplex, another putative hydrogenase, and by substituting NAD+-dependent enzymes with ferredoxin-dependent enzymes thus highlighting a new pattern of mycobacterial adaptation to hypoxia. The expression of ferredoxins and a hydrogenase provides a potential conduit for disposing of and transferring electrons in the absence of exogenous electron acceptors. The use of ferredoxin-dependent enzymes would allow the cell to maintain a high carbon flux through its central carbon metabolism independent of the NAD+/NADH ratio. These data demonstrate the remarkable metabolic plasticity of the mycobacterial cell and provide a new framework for understanding their ability to survive under low energy conditions and hypoxia.
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PMID:Unique flexibility in energy metabolism allows mycobacteria to combat starvation and hypoxia. 2006 6

Although the primary photochemical events in the facultative photoheterotrophic purple bacterium Rhodobacter sphaeroides are now well understood, comparatively little is known about how their photosynthetic apparatus is assembled. Here we present a proteomic analysis of the intracytoplasmic membrane (ICM) assembly process during adaptation to lowered light intensity, in which the size of the photosynthetic units is greatly expanded by addition of the light-harvesting 2 (LH2) peripheral antenna complex. When the isolated ICM-derived chromatophore vesicles were subjected to clear native gel electrophoresis (CNE), four pigmented bands appeared; the top and bottom bands contained the reaction center - light-harvesting 1 (RC-LH1) core complex and LH2 peripheral antenna, respectively, while the two bands of intermediate migration contained associations of the LH2 and core complexes. Proteomic analysis revealed a large array of other proteins associated with the CNE gel bands - in particular, several F(1)F(O)-ATP synthase subunits gave unexpectedly high spectral counts, given the inability to detect this coupling factor, as well as the more abundant cytochrome bc (1) complex, by atomic force microscopy. Significant levels of general membrane assembly factors were also found, as well as numerous proteins of unknown function including high counts for RSP6124 that were correlated with LH2 levels. When combined with further AFM and spectroscopic studies, these proteomic approaches are expected to provide a much-improved understanding of the overall assembly process.
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PMID:Proteomic analysis of the developing intracytoplasmic membrane in Rhodobacter sphaeroides during adaptation to low light intensity. 2053 41


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