At5g50600 encodes a member of the short-chain dehydrogenase reductase superfamily with 11β- and 17β-hydroxy steroid dehydrogenase activities associated with Arabidopsis thaliana seed oil bodies
At5g50600 encodes a member of the short-chain dehydrogenase reductase superfamily with 11β- and 17β-hydroxy steroid dehydrogenase activities associated with Arabidopsis thaliana seed oil bodies
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DOI：
10.1016/j.biochi.2006.09.013
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发表时间：
2007-02-01
期刊：
影响因子：
3.9
通讯作者：
Chardot, T.
中科院分区：
文献类型：
--
作者：
d'Andrea, S.;Canonge, M.;Chardot, T.
在之前的工作中，我们提出了在拟南芥油体（OBs）中存在由At5g50600编码的蛋白质的证据[P. 5]。乔丽薇，李晓明，李晓明，李晓明。拟南芥油体蛋白质组成的研究进展，植物生理学报。生物化学，42(2004):501-509。利用特异性抗体和蛋白质技术，我们目前证实了这种蛋白的存在，它是短链类固醇脱氢酶还原酶超家族的成员。我们已经测量了它对各种类固醇（胆固醇、脱氢表雄酮、皮质醇、皮质酮、雌二醇、雌酮）和NAD(P)(H)的活性，无论是在纯化的ob内还是作为纯化的细菌表达嵌合体。两种酶系统（从拟南芥种子中纯化的OBs和嵌合酶）都表现出对雌二醇（17 β -羟基类固醇）的羟基类固醇脱氢酶（HSD）活性，NAD+或NADP(+) NADP+是首选的辅助因子。皮质醇或皮质酮（il - 3-羟基类固醇）的活性水平较低，但无论使用何种辅助因子，胆固醇和脱氢表雄酮（3 - β -羟基类固醇）都不是底物。两种酶源的活性谱相似。纯化后的OBs还能通过NADPH催化雌酮还原（17 β -酮类固醇还原酶活性）。拟南芥OBs中发生的酶可归类为NADP+依赖性11 β，17 β -羟基类固醇脱氢酶/17 β -酮类固醇还原酶。该酶可能与At5g50600编码的AtHSD1相对应。然而，其生理作用和底物尚未确定。(c) 2006 Elsevier Masson SAS。版权所有。
In a previous work, we presented evidence for the presence of a protein encoded by At5g50600 in oil bodies (OBs) from Arabidopsis thaliana [P. Jolivet, E. Roux, S. D'Andrea, M. Davanture, L. Negroni, M. Zivy, T. Charclot, Protein composition of oil bodies in Arabidopsis thaliana lecotype WS, Plant Physiol. Biochem. 42 (2004) 501-509]. Using specific antibodies and proteomi c techniques, we presently confirm the existence of this protein, which is a member of the short-chain steroid dehydrogenase reductase superfamily. We have measured its activity toward various steroids (cholesterol, dehydroepiandrosterone, cortisol, corticosterone, estradiol, estrone) and NAD(P)(H), either within purified OBs or as a purified bacterially expressed chimera. Both enzymatic systems (OBs purified from A. thaliana seeds as well as the chimeric enzyme) exhibited hydroxysteroid dehydrogenase (HSD) activity toward estradiol (17 beta-hydroxysteroid) with NAD+ or NADP(+) NADP+ being the preferred cofactor. Low levels of activity were observed with cortisol or corticosterone (Ill3-hydroxysteroids), but neither cholesterol nor DHEA (3 beta-hydroxysteroids) were substrates, whatever the cofactor used. Similar activity profiles were found for both enzyme sources. Purified OBs were found to be also able to catalyze estrone reduction (17 beta-ketosteroid reductase activity) with NADPH. The enzyme occurring in A. thaliana OBs can be classified as a NADP+-dependent 11 beta,17 beta-hydroxysteroid dehydrogenase/17 beta-ketosteroid reductase. This enzyme probably corresponds to AtHSD1, which is encoded by At5g50600. However, its physiological role and substrates still remain to be determined. (c) 2006 Elsevier Masson SAS. All rights reserved.