Participation of thioredoxin in the V(V)-reduction reaction by Vanabin2
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ID | 39966 |
本文ファイル | |
著者 |
Uwagaki, Masayuki
Yamamoto, Sohei
Michibata, Hitoshi
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キーワード | Ascidian
Vanadium
Reductase
Metal
Redox
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NDC |
生物科学・一般生物学
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抄録(英) | Background: It is well-understood that ascidians accumulate high levels of vanadium, a reduced form of V(III), in an extremely acidic vacuole in their blood cells. Vanabins are small cysteine-rich proteins that have been identified only from vanadium-rich ascidians. A previous study revealed that Vanabin2 can act as a V(V)-reductase in the glutathione cascade.
Methods: AsTrx1, A thioredoxin gene, was cloned from the vanadium-rich ascidian, Ascidia sydneiensis samea, by PCR. AsTrx1 and Vanabin2 were prepared as recombinant proteins, and V(V)-reduction by Vanabin2 was assessed by ESR and ion-exchange column chromatography. Site-directed mutagenesis was performed to examine the direct involvement of cysteine residues. Tissue expression of AsTrx1 was also examined by RT-PCR. Results: When reduced AsTrx1 and Vanabin2 were combined, Vanabin2 adopted an SS/SH intermediate structure while V(V) was reduced to V(IV). The loss of cysteine residues in either Vanabin2 or AsTrx1 caused a significant loss of reductase activity. Vapp and Kapp values for Vanabin2-catalyzed V(V)-reduction in the thioredoxin cascade were 0.066 mol-V(IV)/min/mol-Vanabin2 and 0.19 mM, respectively. The Kapp value was 2.7-fold lower than that observed in the glutathione cascade. The AsTrx1 gene was expressed at a very high level in blood cells, in which Vanabins 1–4 were co-expressed. Conclusions: AsTrx1 may contribute to a significant part of the redox cascade for V(V)-reduction by Vanabin2 in the cytoplasm of vanadocytes, but prevails only at low V(V) concentrations. General significance: This study is the first to report the reduction of V(V) in the thioredoxin cascade. |
内容記述 | This work was supported in part by Grants-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Nos. 20570070, 21570077, 22224011, 25120508 and 25440170).
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掲載誌名 |
Biochimica et Biophysica Acta (BBA) - General Subjects
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巻 | 1840巻
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号 | 11号
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開始ページ | 3238
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終了ページ | 3245
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出版年月日 | 2014-11
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出版者 | Elsevier B.V.
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ISSN | 0304-4165
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NCID | |
出版者DOI | |
言語 |
英語
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NII資源タイプ |
学術雑誌論文
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広大資料タイプ |
学術雑誌論文
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DCMIタイプ | text
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フォーマット | application/pdf
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著者版フラグ | author
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権利情報 | Copyright (c) 2014 Elsevier B.V. All rights reserved.
This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
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関連情報URL(IsVersionOf) | http://doi.org/10.1016/j.bbagen.2014.07.023
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部局名 |
理学研究科
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