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981.
982.
Zhen Yan Shinya FushinobuTakayoshi Wakagi 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(4):736-743
Heterodimeric 2-oxoacid:ferredoxin oxidoreductase (OFOR) from Sulfolobus tokodaii (StOFOR) has only one [4Fe–4S]2 + cluster, ligated by 4 Cys residues, C12, C15, C46, and C197. The enzyme has no other Cys. To elucidate the role of these Cys residues in holding of the iron–sulfur cluster in the course of oxidative decarboxylation of a 2-oxoacid, one or two of these Cys residues was/were substituted with Ala to yield C12A, C15A, C46A, C197A and C12/15A mutants. All the mutants showed the loss of iron–sulfur cluster, except the C197A one which retained some unidentified type of iron–sulfur cluster. On addition of pyruvate to OFOR, the wild type enzyme exhibited a chromophore at 320 nm and a stable large EPR signal corresponding to a hydroxyethyl-ThDP radical, while the mutant enzymes did not show formation of any radical intermediate or production of acetyl-CoA, suggesting that the intact [4Fe–4S] cluster is necessary for these processes. The stable radical intermediate in wild type OFOR was rapidly decomposed upon addition of CoA in the absence of an electron acceptor. Non-oxidative decarboxylation of pyruvate, yielding acetaldehyde, has been reported to require CoA for other OFORs, but StOFOR catalyzed acetaldehyde production from pyruvate independent of CoA, regardless of whether the iron–sulfur cluster is intact [4Fe–4S] type or not. A comprehensive reaction scheme for StOFOR with a single cluster was proposed. 相似文献
983.
Changes in dopamine (DA) signaling have been implicated in a number of human neurologic
and psychiatric disorders. Similarly, defects in DA signaling in the fruit fly,
Drosophila melanogaster, have also been associated with several
behavioral defects. As most genes involved in DA synthesis, transport, secretion, and
signaling are conserved between species, Drosophila is a powerful genetic
model organism to study the regulation of DA signaling in vivo. In this
review, we will provide an overview of the genes and drugs that regulate DA biology in
Drosophila. Furthermore, we will discuss the behavioral paradigms that
are regulated by DA signaling in flies. By analyzing the genes and neuronal circuits that
govern such behaviors using sophisticated genetic, pharmacologic, electrophysiologic, and
imaging approaches in Drosophila, we will likely gain a better
understanding about how this neuromodulator regulates motor tasks and cognition in
humans. 相似文献
984.
Ryuji Kondo Misa Kodera Yumi Mori Takahiko Okamura Shinya Yoshikawa Kaori Ohki 《Limnology》2014,15(1):77-83
The spatiotemporal distribution of chlorophyll pigments (chloropigments) in the water column of a meromictic lake, Lake Suigetsu (Fukui, Japan), was investigated. Water samples were collected from the central basin of Lake Suigetsu bimonthly between May 2008 and March 2010 at appropriate depths, including the oxic surface, oxic–anoxic interface, and anoxic bottom layers. Chlorophyll a, related to cyanobacteria and eukaryotic phytoplankton, was detected throughout the water column during the years of the study, whereas bacteriochlorophyll e, related to brown-colored green sulfur bacteria, was detected in the anoxic layers below the chemocline at a maximum concentration of 825 μg L?1. The concentration of bacteriochlorophyll e was generally maximal at or just below the chemocline of the lake. The cellular content of bacteriochlorophyll e was estimated to be low in the upper part of the chemocline and tended to increase with increasing water depth. Bacteriochlorophyll a, which was presumably related to purple sulfur bacteria, was only detected at the chemocline during summer and autumn at concentrations of 5.4–16.3 μg L?1. Our analysis of the chloropigment distribution for the two years of the study suggested that brown-colored green sulfur bacteria are the predominant phototroph in the anoxic layers of Lake Suigetsu, and that these play a significant role in the carbon and sulfur cycling of the lake, especially from spring to summer. 相似文献
985.
As the first structure of the novel class of fructose-1,6-bisphosphatase (FBPase) present in thermophilic archaea, we solved the crystal structure of the ST0318 gene product (St-Fbp) of Sulfolobus tokodaii strain 7. The St-Fbp structure comprises a homooctamer of the 422 point-group. The protein folds as a four-layer alpha-beta-beta-alpha sandwich with a novel topology, which is completely different from the sugar phosphatase fold. The structure contains an unhydrolyzed FBP molecule in the open-keto form, as well as four hexacoordinated magnesium ions around the 1-phosphoryl group of FBP. The arrangement of the catalytic side chains and metal ligands is consistent with the three-metal ion assisted catalysis proposed for conventional FBPases. The structure provides an insight into the structural basis of the strict substrate specificity of St-Fbp. 相似文献
986.
Lignins and lignocellulosics: a better control of synthesis for new and improved uses 总被引:13,自引:0,他引:13
The composition and structure of lignified walls has a dramatic impact on the technological value of raw materials. The chemical flexibility of the secondary cell wall has been demonstrated and it is now possible to develop strategies to optimize its composition through genetic engineering. Thanks to functional genomics, new target genes of both plant and microbial origin are rapidly becoming available for this purpose and their use will open new avenues for producing tailor-made plant products with improved properties. Moreover, the major proportion of terrestrial plant biomass comprises lignified cell walls and this reservoir of carbon should be increasingly exploited for the production of chemicals and energy within the context of sustainable development. For example, the design of plants suitable for downstream conversion processes, such as the production of bioethanol, and the exploitation of microorganisms and microbial enzymes for biomass pretreatments or for the production of novel chemicals. 相似文献
987.
Noritaka Yokoo Shinji Kaichi Takahiro Mima Shinya Yamanaka Toshio Heike 《Biochemical and biophysical research communications》2009,387(3):482-488
Developing effective drug therapies for arrhythmic diseases is hampered by the fact that the same drug can work well in some individuals but not in others. Human induced pluripotent stem (iPS) cells have been vetted as useful tools for drug screening. However, cardioactive drugs have not been shown to have the same effects on iPS cell-derived human cardiomyocytes as on embryonic stem (ES) cell-derived cardiomyocytes or human cardiomyocytes in a clinical setting. Here we show that current cardioactive drugs affect the beating frequency and contractility of iPS cell-derived cardiomyocytes in much the same way as they do ES cell-derived cardiomyocytes, and the results were compatible with empirical results in the clinic. Thus, human iPS cells could become an attractive tool to investigate the effects of cardioactive drugs at the individual level and to screen for individually tailored drugs against cardiac arrhythmic diseases. 相似文献
988.
Kiyoshi Okado Hiroka Aonuma Shinya Fukumoto Shin-ichiro Kawazu 《Biochemical and biophysical research communications》2009,379(1):6-159
Genetic variation in susceptibility to pathogens is a central concern both to medicine and agriculture and to the evolution of animals. Here, we have investigated the link between such natural genetic variation and the immune response in wild-type Drosophila melanogaster, a major model organism for immunological research. We found that within nine wild-type strains, different Drosophila genotypes show wide-ranging variation in their ability to survive infection from the pathogenic bacteria Listeria monocytogenes. Canton-S, a resistant strain, showed increased capacity to induce stronger innate immune activities (antimicrobial peptides (AMPs), phenol oxidase activity, and phagocytosis) compared to the susceptible strain (white) at early time points during bacterial infection. Moreover, PGRP-LE-induced innate immune activation immediately after infection greatly improves survival of the susceptible strain strongly suggesting a mechanism behind the natural genetic variation of these two strains. Taken together we provide the first experimental evidence to suggest that differences in innate immune activity at early time points during infection likely mediates infection susceptibility in Drosophila. 相似文献
989.
Junya Kobayashi Hiroshi Tauchi Sandeep Bruma Shinya Matsuura David J. Chen 《Biochemical and biophysical research communications》2009,380(4):752-2839
Phosphorylated histone H2AX (γ-H2AX) functions in the recruitment of DNA damage response proteins to DNA double-strand breaks (DSBs) and facilitates DSB repair. ATM also co-localizes with γ-H2AX at DSB sites following its auto-phosphorylation. However, it is unclear whether γ-H2AX has a role in activation of ATM-dependent cell cycle checkpoints. Here, we show that ATM as well as NBS1 is recruited to damaged-chromatin in a γ-H2AX-dependent manner. Foci formation of phosphorylated ATM and ATM-dependent phosphorylation is repressed in H2AX-knockdown cells. Furthermore, anti-γ-H2AX antibody co-immunoprecipitates an ATM-like protein kinase activity in vitro and recombinant H2AX increases in vitro kinase activity of ATM from un-irradiated cells. Moreover, H2AX-deficient cells exhibited a defect in ATM-dependent cell cycle checkpoints. Taken together, γ-H2AX has important role for effective DSB-dependent activation of ATM-related damage responses via NBS1. 相似文献
990.
Nishioku T Dohgu S Takata F Eto T Ishikawa N Kodama KB Nakagawa S Yamauchi A Kataoka Y 《Cellular and molecular neurobiology》2009,29(3):309-316
The blood–brain barrier (BBB) is highly restrictive of the transport of substances between blood and the central nervous system.
Brain pericytes are one of the important cellular constituents of the BBB and are multifunctional, polymorphic cells that
lie within the microvessel basal lamina. The present study aimed to evaluate the role of pericytes in the mediation of BBB
disruption using a lipopolysaccharide (LPS)-induced model of septic encephalopathy in mice. ICR mice were injected intraperitoneally
with LPS or saline and were sacrificed at 1, 3, 6, and 24 h after injection. Sodium fluorescein accumulated with time in the
hippocampus after LPS injection; this hyperpermeability was supported by detecting the extravasation of fibrinogen. Microglia
were activated and the number of microglia increased with time after LPS injection. LPS-treated mice exhibited a broken basal
lamina and pericyte detachment from the basal lamina at 6–24 h after LPS injection. The disorganization in the pericyte and
basal lamina unit was well correlated with increased microglial activation and increased cerebrovascular permeability in LPS-treated
mice. These findings suggest that pericyte detachment and microglial activation may be involved in the mediation of BBB disruption
due to inflammatory responses in the damaged brain. 相似文献