Mutation Analysis of the Presenilin 1 N-terminal Domain Reveals a Broad Spectrum of γ-Secretase Activity toward Amyloid Precursor Protein and Other Substrates
Mutation Analysis of the Presenilin 1 N-terminal Domain Reveals a Broad Spectrum of γ-Secretase Activity toward Amyloid Precursor Protein and Other Substrates
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DOI：
10.1074/jbc.m110.132613
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发表时间：
2010-12-03
影响因子：
4.8
通讯作者：
Thinakaran, Gopal
中科院分区：
文献类型：
--
作者：
Gong, Ping;Vetrivel, Kulandaivelu S.;Thinakaran, Gopal
γ -分泌酶蛋白复合物执行淀粉样前体蛋白（APP）的膜内蛋白水解，释放阿尔茨海默病β -淀粉样肽。除了APP， γ -分泌酶还切割其他几种I型膜蛋白底物，包括Notch1和N-cadherin。γ -分泌酶由四种完整的跨膜蛋白亚基组成：早老素（PS）、nicastrin、APH1和PEN2。多项证据表明，ps衍生的N端和c端片段的异聚体是γ -分泌酶的催化亚基。只有有限的信息可用于识别和招募不同底物以及将底物转移到催化位点的每个亚基内的结构域。在这里，我们对PS1的两个结构域，即第一腔环结构域（LL1）和第二跨膜结构域（TM2）进行了诱变，并分析了PS1的内源性蛋白水解以及PS1对APP、Notch和N-cadherin的催化活性。我们的研究结果表明，LL1和TM2结构域内的不同残基以及LL1结构域的长度对PS1内源性蛋白水解至关重要，但对PS1与nicastrin、APH1和PEN2形成复合物并不重要。此外，我们的实验PS1突变体形成了对本研究中检测的三种底物具有不同催化性质的γ -分泌酶复合物；然而，突变不影响PS1与底物的相互作用。我们得出结论，n端LL1和TM2结构域对于PS1内源性蛋白水解和假设底物对接位点与γ -分泌酶催化核心之间的协调至关重要。
The gamma-secretase protein complex executes the intramembrane proteolysis of amyloid precursor protein (APP), which releases Alzheimer disease beta-amyloid peptide. In addition to APP, gamma-secretase also cleaves several other type I membrane protein substrates including Notch1 and N-cadherin. gamma-Secretase is made of four integral transmembrane protein subunits: presenilin (PS), nicastrin, APH1, and PEN2. Multiple lines of evidence indicate that a heteromer of PS-derived N- and C-terminal fragments functions as the catalytic subunit of gamma-secretase. Only limited information is available on the domains within each subunit involved in the recognition and recruitment of diverse substrates and the transfer of substrates to the catalytic site. Here, we performed mutagenesis of two domains of PS1, namely the first luminal loop domain (LL1) and the second transmembrane domain (TM2), and analyzed PS1 endoproteolysis as well as the catalytic activities of PS1 toward APP, Notch, and N-cadherin. Our results show that distinct residues within LL1 and TM2 domains as well as the length of the LL1 domain are critical for PS1 endoproteolysis, but not for PS1 complex formation with nicastrin, APH1, and PEN2. Furthermore, our experimental PS1 mutants formed gamma-secretase complexes with distinct catalytic properties toward the three substrates examined in this study; however, the mutations did not affect PS1 interaction with the substrates. We conclude that the N-terminal LL1 and TM2 domains are critical for PS1 endoproteolysis and the coordination between the putative substrate-docking site and the catalytic core of the gamma-secretase.