Participation of Transmembrane Domain 1 of Presenilin 1 in the Catalytic Pore Structure of the γ-Secretase
Participation of Transmembrane Domain 1 of Presenilin 1 in the Catalytic Pore Structure of the γ-Secretase
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DOI：
10.1523/jneurosci.3318-10.2010
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发表时间：
2010-11-24
影响因子：
5.3
通讯作者：
Iwatsubo, Takeshi
中科院分区：
文献类型：
--
作者：
Takagi, Shizuka;Tominaga, Aya;Iwatsubo, Takeshi
γ -分泌酶是一种膜内切割蛋白酶，负责淀粉样肽的产生，与阿尔茨海默病的发病机制有关。使用替代半胱氨酸接近性方法，我们之前已经证明-分泌酶的亲水“催化孔”结构是由-分泌酶的催化亚基-早老素1 （PS1）的跨膜结构域（TMDs） 6、7和9形成的。在这里，我们分析了PS1的第一个疏水区域（假定的TMD1）内和周围的结构，其精确功能以及在γ -分泌酶中的三维位置仍然未知。我们发现TMD1位于PS1 c端片段的催化GxGD和PAL基序附近，直接面向催化孔。使用已知γ -分泌酶抑制剂的竞争实验表明，TMD1的n端区域在γ -分泌酶的蛋白水解作用中起着亚位点的作用。有趣的是，抑制剂的结合影响了TMD1膜边界残基的水可及性，这表明TMD1在催化过程中可能存在动态运动。我们的研究结果为PS1的TMD1在γ -分泌酶的膜内切割活性中的功能作用提供了机制见解。
gamma-Secretase is an intramembrane-cleaving protease that is responsible for the generation of amyloid-beta peptides linked to the pathogenesis of Alzheimer's disease. Using a substituted cysteine accessibility method, we have previously shown that the hydrophilic "catalytic pore" structure of gamma-secretase is formed by the transmembrane domains (TMDs) 6, 7, and 9 of presenilin 1 (PS1), the catalytic subunit of gamma-secretase, within the membrane. Here, we analyzed the structure in and around the first hydrophobic region, the putative TMD1, of PS1, of which the precise function as well as three-dimensional location within gamma-secretase remained unknown. We found that TMD1 is located in proximity to the catalytic GxGD and PAL motifs within the C-terminal fragment of PS1, facing directly the catalytic pore. Competition experiments using known gamma-secretase inhibitors suggested that the N-terminal region of TMD1 functions as a subsite during proteolytic action of the gamma-secretase. Intriguingly, binding of inhibitors affected water accessibility of residues at the membrane border of TMD1, suggesting the possibility of a dynamic motion of TMD1 during the catalytic process. Our results provide mechanistic insights into the functional role of TMD1 of PS1 in the intramembrane-cleaving activity of the gamma-secretase.