Expanded substrate screenings of human and Drosophila type 10 17β-hydroxysteroid dehydrogenases (HSDs) reveal multiple specificities in bile acid and steroid hormone metabolism:: characterization of multifunctional 3α/7α/7β/17β/20β/21-HSD
Expanded substrate screenings of human and Drosophila type 10 17β-hydroxysteroid dehydrogenases (HSDs) reveal multiple specificities in bile acid and steroid hormone metabolism:: characterization of multifunctional 3α/7α/7β/17β/20β/21-HSD
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DOI：
10.1042/bj20030877
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发表时间：
2003-11-15
影响因子：
4.1
通讯作者：
Oppermann, U
中科院分区：
文献类型：
--
作者：
Shafqat, N;Marschall, HU;Oppermann, U
17 β-羟基类固醇脱氢酶（17 β-HSDs）催化类固醇的17 β-OH（-羟基）/17-氧代基团的转化，并且在哺乳动物激素生理学中是必需的。目前，在哺乳动物中已经确定了11种17 β-HSD异构体，具有不同的组织表达和底物转化模式。我们分析了来自人类和果蝇的17 β-HSD 10型（17 β-HSD10），后者已知在发育中是必需的。除了已知的羟酰辅酶A脱氢酶和3 α-OH和17 β-OH与性类固醇的活性外，我们在这里证明了17 β-HSD10的新活性。这两种物种变体氧化C-21类固醇中的20 β-OH和21-OH基团，并作为熊去氧胆酸或异熊去氧胆酸（也分别称为7 β-羟基石胆酸或7 β-羟基异石胆酸）的7 β-OH脱氢酶。此外，人直系同源物氧化chenodcoxycholic acid（5beta-cholanic acid，3alpha，7alpha-diol）和cholic acid（5beta-cholanic acid）的7alpha-OH。这些新的底物特异性解释的同源模型的基础上的orthoparrat晶体结构，显示出广泛的疏水性裂缝，能够容纳类固醇在不同的方向。这些性质表明，人类酶参与糖皮质激素和孕激素catastrin，并参与胆汁酸异构化。共聚焦显微镜和电子显微镜研究表明，人类形式是本地化的线粒体，而果蝇17 β-HSD10显示胞质定位模式，可能是由于N-末端序列的差异，在人类17 β-HSD10构成线粒体靶向信号，延伸到罗斯曼折叠基序。
17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) catalyse the conversion of 17beta-OH (-hydroxy)/17-oxo groups of steroids, and are essential in mammalian hormone physiology. At present, eleven 17beta-HSD isoforms have been defined in mammals, with different tissue-expression and substrate-conversion patterns. We analysed 17beta-HSD type 10 (17beta-HSD10) from humans and Drosophila, the latter known to be essential in development. In addition to the known hydroxyacyl-CoA dehydrogenase, and 3alpha-OH and 17beta-OH activities with sex steroids, we here demonstrate novel activities of 17beta-HSD10. Both species variants oxidize the 20beta-OH and 21-OH groups in C-21 steroids, and act as 7beta-OH dehydrogenases of ursodeoxycholic or isoursodeoxycholic acid (also known as 7beta-hydroxylithocholic acid or 7beta-hydroxyisolithocholic acid respectively). Additionally, the human orthologue oxidizes the 7alpha-OH of chenodcoxycholic acid (5beta-cholanic acid, 3alpha,7alpha-diol) and cholic acid (5beta-cholanic acid). These novel substrate specificities are explained by homology models based on the orthologous rat crystal structure, showing a wide hydrophobic cleft, capable of accommodating steroids in different orientations. These properties suggest that the human enzyme is involved in glucocorticoid and gestagen catabolism, and participates in bile acid isomerization. Confocal microscopy and electron microscopy studies reveal that the human form is localized to mitochondria, whereas Drosophila 17beta-HSD10 shows a cytosolic localization pattern, possibly due to an N-terminal sequence difference that in human 17beta-HSD 10 constitutes a mitochondrial targeting signal, extending into the Rossmann-fold motif.