Structure of the catalytic pore of γ-secretase probed by the accessibility of substituted cysteines
Structure of the catalytic pore of γ-secretase probed by the accessibility of substituted cysteines
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DOI：
10.1523/jneurosci.3614-06.2006
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发表时间：
2006-11-15
影响因子：
5.3
通讯作者：
Iwatsubo, Takeshi
中科院分区：
文献类型：
--
作者：
Sato, Chihiro;Morohashi, Yuichi;Iwatsubo, Takeshi
几种单跨膜蛋白在其跨膜结构域（TMD）内被膜内切割蛋白酶切割，尽管执行膜内切割的活性位点的结构仍然未知。在这里，我们使用取代的半胱氨酸可及性方法来检查早老素-1的结构，早老素-1是γ-分泌酶的催化亚基，参与阿尔茨海默病和Notch信号传导中的淀粉样β蛋白生成。我们发现，TMD 6和TMD 7的早老素-1有助于形成一个亲水性孔内的膜。预测在TMD 6的管腔部分的残基形成底物或抑制剂结合在α-螺旋上的子位点，其面向亲水环境，而在TMD 7内的GxGD催化基序周围的那些残基是高度水可接近的，这表明在孔内形成亲水结构。总的来说，我们的数据表明，γ-分泌酶的活性位点位于脂双层内充满水的催化孔中，并在催化剂上呈锥形。
Several single-span membrane proteins are cleaved within their transmembrane domains (TMDs) by intramembrane-cleaving proteases, although the structure of the active site executing intramembrane cleavage remains unknown. Here we use the substituted cysteine accessibility method to examine the structure of presenilin-1, a catalytic subunit of gamma-secretase, involved in amyloid beta protein generation in Alzheimer's disease and Notch signaling. We show that TMD6 and TMD7 of presenilin-1 contribute to the formation of a hydrophilic pore within the membrane. Residues at the luminal portion of TMD6 are predicted to form a subsite for substrate or inhibitor binding on the alpha-helix facing a hydrophilic milieu, whereas those around the GxGD catalytic motif within TMD7 are highly water accessible, suggesting formation of a hydrophilic structure within the pore. Collectively, our data suggest that the active site of gamma-secretase resides in a catalytic pore filled with water within the lipid bilayer and is tapered around the catalytic aspartates.