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901.
Tatsuro Maruyama Shunsuke Imai Masanori Osawa Motoyuki Hattori Ryuichiro Ishitani Osamu Nureki Ichio Shimada 《Biomolecular NMR assignments》2013,7(1):93-96
Magnesium ion (Mg2+) is an essential metal element for life, and has many cellular functions, including ATP utilization, activation of enzymes, and maintenance of genomic stability. The intracellular Mg2+ concentration is regulated by a class of transmembrane proteins, called Mg2+ transporters. One of the prokaryotic Mg2+ transporters, MgtE, is a 450-residue protein, and functions as a dimer. We previously reported that MgtE exhibits the channel-like electrophysiological property, i.e., it permeates Mg2+ according to the electrochemical potential of Mg2+. The Mg2+-permeation pathway opens in response to the decrease of the intracellular Mg2+ concentration, while it is completely closed at the intracellular Mg2+ concentration of 10 mM. The crystal structures of the MgtE dimer revealed that the Mg2+-sensing cytoplasmic region consists of the N and CBS domains. The Mg2+-bound state of MgtE adopts a compact, globular conformation, which is stabilized by the coordination of a number of Mg2+ ions between these domains. On the other hand, in the Mg2+-unbound state, these domains are far apart, and fixed by the crystal packing. Therefore, structural analyses in solution were awaited, in order to characterize the Mg2+-dependent alteration of the MgtE structure and dynamics relevant to its gating. In this paper, we report the backbone resonance assignments of the dimer of the cytoplasmic region of the MgtE from Thermus thermophilus with a molecular weight of 60 KDa, in the Mg2+-unbound state. 相似文献
902.
Shinya Okamoto Yuanyuan Jiang Kiyoko Kawamura Masato Shingyoji Toshihiko Fukamachi Yuji Tada Yuichi Takiguchi Koichiro Tatsumi Hideaki Shimada Kenzo Hiroshima Hiroshi Kobayashi Masatoshi Tagawa 《PloS one》2013,8(3)
We examined anti-tumor effects of zoledronic acid (ZOL), one of the bisphosphonates agents clinically used for preventing loss of bone mass, on human mesothelioma cells bearing the wild-type p53 gene. ZOL-treated cells showed activation of caspase-3/7, -8 and -9, and increased sub-G1 phase fractions. A combinatory use of ZOL and cisplatin (CDDP), one of the first-line anti-cancer agents for mesothelioma, synergistically or additively produced the cytotoxicity on mesothelioma cells. Moreover, the combination achieved greater anti-tumor effects on mesothelioma developed in the pleural cavity than administration of either ZOL or CDDP alone. ZOL-treated cells as well as CDDP-treated cells induced p53 phosphorylation at Ser 15, a marker of p53 activation, and up-regulated p53 protein expression levels. Down-regulation of p53 levels with siRNA however did not influence the ZOL-mediated cytotoxicity but negated the combinatory effects by ZOL and CDDP. In addition, ZOL treatments augmented cytotoxicity of adenoviruses expressing the p53 gene on mesothelioma. These data demonstrated that ZOL-mediated augmentation of p53, which was not linked with ZOL-induced cytotoxicity, played a role in the combinatory effects with a p53 up-regulating agent, and suggests a possible clinical use of ZOL to mesothelioma with anti-cancer agents. 相似文献
903.
Eiryu Sai Kazunori Shimada Takayuki Yokoyama Shuji Sato Tetsuro Miyazaki Makoto Hiki Yoshifumi Tamura Shigeki Aoki Hirotaka Watada Ryuzo Kawamori Hiroyuki Daida 《PloS one》2013,8(4)
Ectopic fat accumulation plays important roles in various metabolic disorders and cardiovascular diseases. Recent studies reported that myocardial triglyceride (TG) content measured by proton magnetic resonance spectroscopy (1H-MRS) is associated with aging, diabetes mellitus, and cardiac dysfunction. However, myocardial TG content in athletes has not yet been investigated. We performed 1H-MRS and cardiac magnetic resonance imaging in 10 male endurance athletes and 15 healthy male controls. Serum markers and other clinical parameters including arterial stiffness were measured. Cardiopulmonary exercise testing was also performed. There were no significant differences in clinical characteristics including age, anthropometric parameters, blood test results, or arterial stiffness between the two groups. Peak oxygen uptakes, end–diastolic volume (EDV), end–systolic volume (ESV), left ventricular (LV) mass, peak ejection rates and peak filling rates were significantly higher in the athlete group than in the control group (all P<0.02). Myocardial TG content was significantly lower in the athlete group than in the control group (0.60±0.20 vs. 0.89±0.41%, P<0.05). Myocardial TG content was negatively correlated with EDV (r = −0.47), ESV (r = −0.64), LV mass (r = −0.44), and epicardial fat volume (r = 0.47) (all P<0.05). In conclusion, lower levels of myocardial TG content were observed in endurance athletes and were associated with morphological changes related to physiological LV alteration in athletes, suggesting that metabolic imaging for measurement of myocardial TG content by 1H-MRS may be a useful technique for noninvasively assessing the “athlete’s heart”. 相似文献
904.
Takao Suzuki Hiroyuki Shimada Hyuma Makizako Takehiko Doi Daisuke Yoshida Kengo Ito Hiroshi Shimokata Yukihiko Washimi Hidetoshi Endo Takashi Kato 《PloS one》2013,8(4)
Background
To examine the effect of multicomponent exercise program on memory function in older adults with mild cognitive impairment (MCI), and identify biomarkers associated with improvement of cognitive functions.Methodology/Principal Findings
Subjects were 100 older adults (mean age, 75 years) with MCI. The subjects were classified to an amnestic MCI group (n = 50) with neuroimaging measures, and other MCI group (n = 50) before the randomization. Subjects in each group were randomized to either a multicomponent exercise or an education control group using a ratio of 1∶1. The exercise group exercised for 90 min/d, 2 d/wk, 40 times for 6 months. The exercise program was conducted under multitask conditions to stimulate attention and memory. The control group attended two education classes. A repeated-measures ANOVA revealed that no group × time interactions on the cognitive tests and brain atrophy in MCI patients. A sub-analysis of amnestic MCI patients for group × time interactions revealed that the exercise group exhibited significantly better Mini-Mental State Examination (p = .04) and logical memory scores (p = .04), and reducing whole brain cortical atrophy (p<.05) compared to the control group. Low total cholesterol levels before the intervention were associated with an improvement of logical memory scores (p<.05), and a higher level of brain-derived neurotrophic factor was significantly related to improved ADAS-cog scores (p<.05).Conclusions/Significance
The results suggested that an exercise intervention is beneficial for improving logical memory and maintaining general cognitive function and reducing whole brain cortical atrophy in older adults with amnestic MCI. Low total cholesterol and higher brain-derived neurotrophic factor may predict improvement of cognitive functions in older adults with MCI. Further studies are required to determine the positive effects of exercise on cognitive function in older adults with MCI.Trial Registration
UMIN-CTR UMIN000003662 ctr.cgi?function = brows&action = brows&type = summary&recptno = R000004436&language = J. 相似文献905.
Seiichi Mawatari Hirofumi Uto Akio Ido Kenji Nakashima Tetsuro Suzuki Shuji Kanmura Kotaro Kumagai Kohei Oda Kazuaki Tabu Tsutomu Tamai Akihiro Moriuchi Makoto Oketani Yuko Shimada Masayuki Sudoh Ikuo Shoji Hirohito Tsubouchi 《PloS one》2013,8(12)
Background
It has been hypothesized that persistent hepatitis C virus (HCV) infection is mediated in part by viral proteins that abrogate the host immune response, including the complement system, but the precise mechanisms are not well understood. We investigated whether HCV proteins are involved in the fragmentation of complement component 4 (C4), composed of subunits C4α, C4β, and C4γ, and the role of HCV proteins in complement activation.Methods
Human C4 was incubated with HCV nonstructural (NS) 3/4A protease, core, or NS5. Samples were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then subjected to peptide sequencing. The activity of the classical complement pathway was examined using an erythrocyte hemolysis assay. The cleavage pattern of C4 in NS3/4A-expressing and HCV-infected cells, respectively, was also examined.Results
HCV NS3/4A protease cleaved C4γ in a concentration-dependent manner, but viral core and NS5 did not. A specific inhibitor of NS3/4A protease reduced C4γ cleavage. NS3/4A protease–mediated cleavage of C4 inhibited classical pathway activation, which was abrogated by a NS3/4A protease inhibitor. In addition, co-transfection of cells with C4 and wild-type NS3/4A, but not a catalytic-site mutant of NS3/4A, produced cleaved C4γ fragments. Such C4 processing, with a concomitant reduction in levels of full-length C4γ, was also observed in HCV-infected cells expressing C4.Conclusions
C4 is a novel cellular substrate of the HCV NS3/4A protease. Understanding disturbances in the complement system mediated by NS3/4A protease may provide new insights into the mechanisms underlying persistent HCV infection. 相似文献906.
907.
Mayumi Miyazawa-Onami Koh Takeuchi Toshiaki Takano Toshihiko Sugiki Ichio Shimada Hideo Takahashi 《Journal of biomolecular NMR》2013,57(3):297-304
The production of stable isotope-labeled proteins is critical in structural analyses of large molecular weight proteins using NMR. Although prokaryotic expression systems using Escherichia coli have been widely used for this purpose, yeast strains have also been useful for the expression of functional eukaryotic proteins. Recently, we reported a cost-effective stable isotope-labeled protein expression using the hemiascomycete yeast Kluyveromyces lactis (K. lactis), which allow us to express exogenous proteins at costs comparable to prokaryotic expression systems. Here, we report the successful production of highly deuterated (>90 %) protein in the K. lactis system. We also examined the methyl-selective 1H, 13C-labeling of Ile, Leu, and Val residues using commonly used amino acid precursors. The efficiency of 1H- 13C-incorporation varied significantly based on the amino acid. Although a high level of 1H-13C-incorporation was observed for the Ile δ1 position, 1H, 13C-labeling rates of Val and Leu methyl groups were limited due to the mitochondrial localization of enzymes involved in amino acid biosynthesis and the lack of transporters for α-ketoisovalerate in the mitochondrial membrane. In line with this notion, the co-expression with branched-chain-amino-acid aminotransferase in the cytosol significantly improved the incorporation rates of amino acid precursors. Although it would be less cost-effective, addition of 13C-labeled valine can circumvent problems associated with precursors and achieve high level 1H, 13C-labeling of Val and Leu. Taken together, the K. lactis system would be a good alternative for expressing large eukaryotic proteins that need deuteration and/or the methyl-selective 1H, 13C-labeling for the sensitive detection of NMR resonances. 相似文献
908.
Keiko Sasaki Akiko Shimada Keiko Hatae Atsuko Shimada 《Bioscience, biotechnology, and biochemistry》2013,77(9):2273-2278
The effects of the state of mixing on total absorbed energy (P) in microwave cooking were investigated. When water and oil were heated independently, both of P were almost equal and the effect of the dielectric loss factor (ε″) on P was negligible. P of a two-layer sample was almost equal to that of the water component alone and was affected by ε″. P of an emulsion sample was almost constant and equal to that of water alone whose volume was the same as the volume of the sample. The difference between P of a two-layer sample and that of an emulsion sample was thought to be affected by the increase in the water-oil interface area, and it was found that P of the water-oil mixture is influenced by the state of mixing. 相似文献
909.
Hiromasa Miyaji Tatsunari Nishi Akiko Saito Shuichiro Maeda Kazunori Shimada Toshio Hirano 《Bioscience, biotechnology, and biochemistry》2013,77(4):1135-1142
A mature human interleukin 2 (hIl-2) and its derivatives that lacked the N-terminal portion were expressed in Escherichia coli under the control of the phage λ PL promoter. They accumulated in the form of insoluble inclusion bodies and accounted for about 30% of the total cellular protein. The mature hIl-2 and its derivatives were further purified and their in vitro biological activity was compared in an Il-2 microassay. The results suggested that the hIl-2 derivatives without the N- terminal three or five amino acids were as active as intact hIl-2 and that those without the N- terminal eight or nine amino acids were less active than the intact form. 相似文献
910.
In this article, we developed a new and mild procedure for the isolation of chlorosomes from a green sulfur bacterium Chlorobaculum tepidum. In this procedure, Fenna-Matthews-Olson (FMO) protein was released by long cold treatment (6°C) of cells under the presence of a chaotrope (2?M NaSCN) and 0.6?M sucrose. Chlorosomes were released by an osmotic shock of the cold-treated cells after the formation of spheroplasts without mechanical disruption. Chlorosomes were finally purified by a sucrose step-wise density gradient centrifugation. We obtained two samples with different density (20 and 23% sucrose band, respectively) and compared them by SDS-PAGE, absorption spectroscopy at 80?K, fluorescence and CD spectroscopy at room temperature. Cells whose absorption maximum was longer than 750?nm yielded higher amount of the 20% sucrose fraction than those having an absorption maximum shorter than 750?nm. 相似文献