The disulphide bonds in the catalytic domain of BACE are critical but not essential for amyloid precursor protein processing activity
The disulphide bonds in the catalytic domain of BACE are critical but not essential for amyloid precursor protein processing activity
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DOI：
10.1046/j.0022-3042.2002.00806.x
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发表时间：
2002-03-01
影响因子：
4.7
通讯作者：
Paganetti, P
中科院分区：
文献类型：
--
作者：
Fischer, F;Molinari, M;Paganetti, P
β 位点 APP 裂解酶 (BACE) 启动淀粉样前体蛋白 (APP) 的加工，导致产生 β-淀粉样蛋白，β-淀粉样蛋白是阿尔茨海默病老年斑的主要成分。 BACE（Asp2、memapsin 2）是一种 I 型跨膜天冬氨酸蛋白酶，负责 APP 的 β 分泌酶裂解，产生可溶形式的胞外域 (sAPPbeta) 以及膜结合的羧基末端中间体 C99 和 C89。 BACE 成熟涉及半胱氨酸桥形成、N-糖基化和前肽去除。我们研究了 BACE 的变体，其中跨越 Cys216/Cys420、Cys278/Cys443 和 Cys330/Cys380 之间的催化结构域的二硫键通过诱变去除。当转染培养细胞时，这些突变体表现出成熟受损。然而，一小部分突变蛋白保留了成熟的能力以及加工 APP 的活性。对于功能酶的生成，保守的 Cys330/Cys380 键是最关键的，而 Cys216/Cys420 和 Cys278/Cys443 之间的两个键（膜结合 BACE 的典型键）似乎不太重要。
beta-Site APP-cleaving enzyme (BACE) initiates the processing of the amyloid precursor protein (APP) leading to the generation of beta-amyloid, the main component of Alzheimer's disease senile plaques. BACE (Asp2, memapsin 2) is a type I transmembrane aspartic protease responsible for the beta-secretase cleavage of APP producing a soluble form of the ectodomain (sAPPbeta) and the membrane-bound, carboxy-terminal intermediates C99 and C89. BACE maturation involves cysteine bridge formation, N-glycosylation and propeptide removal. We investigated variants of BACE in which the disulphide bonds of the catalytic domain spanning between Cys2l6/Cys420, Cys278/Cys443 and Cys330/Cys380 were removed by mutagenesis. When transfected in cultured cells, these mutants showed impaired maturation. Nevertheless, a fraction of mutated protein retained both the competence to mature as well as the activity to process APP. For the generation of a functional enzyme the conserved Cys330/Cys380 bond was the most critical, whereas the two bonds between Cys216/Cys420 and Cys278/Cys443, which are typical for the membrane-bound BACE, appeared to be less important.