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131.
Yoshimi Tokuzawa Ken Yagi Yzumi Yamashita Yutaka Nakachi Itoshi Nikaido Hidemasa Bono Yuichi Ninomiya Yukiko Kanesaki-Yatsuka Masumi Akita Hiromi Motegi Shigeharu Wakana Tetsuo Noda Fred Sablitzky Shigeki Arai Riki Kurokawa Toru Fukuda Takenobu Katagiri Christian Sch?nbach Tatsuo Suda Yosuke Mizuno Yasushi Okazaki 《PLoS genetics》2010,6(7)
132.
Amr M. Mowafy Tatsuo Kurihara Atsushi Kurata Tadashi Uemura Nobuyoshi Esaki 《Applied and environmental microbiology》2010,76(18):6032-6037
Enzymes catalyzing the conversion of organohalogen compounds are useful in the chemical industry and environmental technology. Here we report the occurrence of a new reduced flavin adenine dinucleotide (FAD) (FADH2)-dependent enzyme that catalyzes the removal of a halogen atom from an unsaturated aliphatic organohalogen compound by the addition of a water molecule to the substrate. A soil bacterium, Pseudomonas sp. strain YL, inducibly produced a protein named Caa67YL when the cells were grown on 2-chloroacrylate (2-CAA). The caa67YL gene encoded a protein of 547 amino acid residues (Mr of 59,301), which shared weak but significant sequence similarity with various flavoenzymes and contained a nucleotide-binding motif. We found that 2-CAA is converted into pyruvate when the reaction was carried out with purified Caa67YL in the presence of FAD and a reducing agent [NAD(P)H or sodium dithionite] under anaerobic conditions. The reducing agent was not stoichiometrically consumed during this reaction, suggesting that FADH2 is conserved by regeneration in the catalytic cycle. When the reaction was carried out in the presence of H218O, [18O]pyruvate was produced. These results indicate that Caa67YL catalyzes the hydration of 2-CAA to form 2-chloro-2-hydroxypropionate, which is chemically unstable and probably spontaneously dechlorinated to form pyruvate. 2-Bromoacrylate, but not other 2-CAA analogs such as acrylate and methacrylate, served as the substrate of Caa67YL. Thus, we named this new enzyme 2-haloacrylate hydratase. The enzyme is very unusual in that it requires the reduced form of FAD for hydration, which involves no net change in the redox state of the coenzyme or substrate.Dehalogenases catalyze the removal of halogen atoms from organohalogen compounds. These enzymes have been attracting a great deal of attention partly because of their possible applications to the chemical industry and environmental technology. Several dehalogenases have been discovered and characterized (6, 11, 14, 17, 22). Some of them act on unsaturated aliphatic organohalogen compounds in which a halogen atom is bound to an sp2-hybridized carbon atom. Examples include various corrinoid/iron-sulfur cluster-containing reductive dehalogenases (1, 7), cis- and trans-3-chloroacrylic acid dehalogenases (4, 19), and LinF (maleylacetate reductase), which acts on 2-chloromaleylacetate (5).In order to gain more insight into the enzymatic dehalogenation of unsaturated aliphatic organohalogen compounds, we searched for microorganisms that dissimilate 2-chloroacrylate (2-CAA) as a sole source of carbon and energy (8). 2-CAA is a bacterial metabolite of 2-chloroallyl alcohol, an intermediate or by-product in the industrial synthesis of herbicides (26). Rats treated orally with the herbicides sulfallate, diallate, and triallate excrete urinary 2-CAA (16). Various halogenated acrylic acids are produced by a red alga (27). We obtained three 2-CAA-utilizing bacteria as a result of screening (8). For one of these bacteria, Burkholderia sp. strain WS, we previously discovered a new NADPH-dependent enzyme, 2-haloacrylate reductase (12, 13). Although this enzyme does not directly remove a halogen atom from the substrate, it is supposed to participate in the metabolism of 2-CAA by catalyzing the conversion of 2-CAA into l-2-chloropropionate, which is subsequently dehalogenated by l-2-haloacid dehalogenase.Another bacterium that we obtained, Pseudomonas sp. strain YL, also dissimilates 2-CAA. However, the metabolic fate of 2-CAA in this bacterium remains unclear. In the present study, we analyzed proteins from 2-CAA- and lactate-grown cells of Pseudomonas sp. YL by two-dimensional polyacrylamide gel electrophoresis (PAGE) and identified a 2-CAA-inducible protein. We found that the protein catalyzes the dehalogenation of 2-CAA by the addition of a water molecule to the substrate, representing a new family of dehalogenases that act on unsaturated aliphatic organohalogen compounds. Remarkably, the enzyme requires reduced flavin adenine dinucleotide (FAD) (FADH2) for its activity, although the reaction does not involve a net change in the redox state of the coenzyme or substrate. Here we describe the occurrence and characteristics of this unusual flavoenzyme. 相似文献
133.
Masamitsu Konno Tatsuo S. Hamazaki Satsuki Fukuda Hideho Uchiyama Hitoshi Okochi Makoto Asashima 《Biochemical and biophysical research communications》2010,400(4):461-465
Adipose tissue-derived mesenchymal stem cells (ASCs) have been reported to be multipotent and to differentiate into various cell types, including osteocytes, adipocytes, chondrocytes, and neural cells. Recently, many authors have reported that ASCs are also able to differentiate into vascular endothelial cells (VECs) in vitro. However, these reports included the use of medium containing fetal bovine serum for endothelial differentiation. In the present study, we have developed a novel method for differentiating mouse ASCs into VECs under serum-free conditions. After the differentiation culture, over 80% of the cells expressed vascular endothelial-specific marker proteins and could take up low-density lipoprotein in vitro. This protocol should be helpful in clarifying the mechanisms of ASC differentiation into the VSC lineage. 相似文献
134.
Toshiyoshi Araki Michio Hayakawa Yutaka Tamaru Keiji Yoshimatsu Tatsuo Morishita 《Journal of phycology》1994,30(6):1040-1046
Three kinds of enzymes, agarase, β-1,4-mannanase, and β-1,3-xylanase, required for isolation of protoplasts from the red alga Bangia atropurpurea (Roth) C. Ag. were prepared from bacterial culture fluids of Vibrio sp. PO-303, Vibrio sp. MA-138, and Alcaligenes sp. XY-234, respectively, isolated from the sea environment. The optimal pH of all enzymes was around 7.5. Suitable conditions for protoplast isolation from B. atropurpurea were examined. The pretreatment of the fronds with pa-pain solution (20 mM Mes buffer, pH 7.5, containing 2% papain and 0.5 M mannitol) contributed to successful protoplast isolation. When razor-cut fragments of the fronds (about 200 mg in fresh weight) immersed in 20 mM Mes buffer, 7.5, containing 0.5 M mannitol and one unit each of agarase, β-1,4-mannanase, and β-1,3-xylanase were incubated at 22°C for 90 min with gentle agitation, 5.7 × 106 protoplasts were released from them. Many protoplasts regenerated into fronds of regular or irregular shape. 相似文献
135.
Keiichi Honda Hisashi Ômura Nanao Hayashi Fumiko Abe Tatsuo Yamauchi 《Physiological Entomology》2001,26(1):6-10
Oviposition response of Ideopsis similis (L.) (Lepidoptera: Danaidae) was examined for 12 phenanthroindolizidine alkaloids present in its host plant, Tylophora tanakae (Maxim.) (Asclepiadaceae). At least five alkaloids, i.e. (+)‐isotylocrebrine (3,4,6,7‐tetramethoxyphenanthroindolizidine; l ), (+)‐3‐demethyliso‐ tylocrebrine ( 3 ), (+)‐isotylocrebrine N‐oxide ( 5 ), (+)‐6‐demethyltylocrebrine ( 8 ) and (–)‐7‐demethyltylophorine ( 10 ), were found to individually stimulate oviposition by females. Of these, compounds 1, 3 and 10 were regarded as key components most responsible for host recognition or preference. However, female egg‐laying was much higher in response to a mixture of the five alkaloids. In two‐choice bioassays, more eggs were deposited on samples comprising the five alkaloids than on samples consisting of a single alkaloid. This suggests strongly that host selection by the butterfly is mediated by the synergistic action of several phenanthroindolizidine alkaloids present in the host plant. 相似文献
136.
Nakayama EE Carpentier W Costagliola D Shioda T Iwamoto A Debre P Yoshimura K Autran B Matsushita S Theodorou I 《Immunogenetics》2007,59(6):511-515
Polymorphisms in human genes have been shown to affect the rate of disease progression to acquired immune deficiency syndrome
in human immunodeficiency virus type 1 (HIV-1)-infected individuals. Recently, tripartite motif 5α (TRIM5α) was identified
as a factor that confers resistance to HIV-1 infection in Old World monkey cells. Subsequently, Sawyer et al. (Curr Biol 16:95–100,
2006) reported a single nucleotide polymorphism (H43Y) in the human TRIM5α gene and TRIM5α protein with 43Y was found to lose its ability to restrict HIV-1. In the present study, we reevaluated effects
of this allele on in vitro anti-HIV-1 activity as well as on HIV-1 disease progression in European and Asian cohorts of HIV-1-infected
individuals. Our epidemiological and molecular biological findings clearly indicate H43Y has a very minor effect on anti-HIV-1
activity of TRIM5α, suggesting that this allele is immaterial, at least in HIV-1-infected Europeans and Asians. 相似文献
137.
Ueki Y Shoji M Suto A Tanabe T Okimura Y Kikuchi Y Saito N Sano D Omura T 《Applied and environmental microbiology》2007,73(17):5698-5701
The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters. 相似文献
138.
Inhibitory effects of gold(III) ions (Au(III)) on ribonuclease A (RNase A) and deoxyribonuclease I (DNase I) were investigated at neutral pH. RNase A was completely inhibited by 3 molar equivalents of Au(III) ions. DNase I was inhibited by 10 molar equivalents of Au(III) ions. Stoichiometric analyses suggest that Au(III) ions were coordinated to RNase A molecules. The Au(III)-inhibited RNase A and DNase I were renatured to exhibit 80% and 60% of their intrinsic activity, when the bound Au(III) ions were eliminated from the nucleases by addition of thiourea, which forms a strong complex with gold ions. This suggests that RNase A and DNase I were not oxidized to lose their activity, but reversibly complexed with Au(III) ions to lose their activity. Au(III) ions were probably considered to be bound to histidine and methionine residues in the nucleases, resulting in the inhibition of their activity. CD spectra revealed that the Au(III)-induced inhibition caused a conformational change in RNase A molecules and that the addition of thiourea induced refolding of the Au(III)-inhibited RNase A. 相似文献
139.
140.
Yoshida K Obata S Ono M Esaki M Maejima T Sawada H 《European journal of cell biology》2007,86(8):461-471
The 5F9A cell, which is a mesenchymal stem cell-like clone established from rat bone marrow substrate adherent cells, can differentiate into adipocytes and osteoblasts in vitro under the appropriate conditions. Multinucleated cells could be also induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) in 5F9A cells. This effect was mediated by protein kinase C. Possible mechanisms of multinucleation by TPA were hypothesized to be either karyokinesis without cytokinesis or cell-cell fusion. By observation using time-lapse phase-contrast microscopy, we determined that the multinucleated cells were generated mainly by karyokinesis without cytokinesis. Cell fusion was studied using time-lapse photography, and confocal laser scanning microscopy using two differentially labeled cells. These techniques demonstrated that multinucleated 5F9A cells could be produced by cell fusion, albeit at a low frequency. We conclude that multinucleated 5F9A cells are formed primarily by karyokinesis without cytokinesis, although some cells are also formed by cell-cell fusion. 相似文献