Pathogenic mutations located in the hydrophobic core of the prion protein interfere with folding and attachment of the glycosylphosphatidylinositol anchor
Pathogenic mutations located in the hydrophobic core of the prion protein interfere with folding and attachment of the glycosylphosphatidylinositol anchor
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DOI：
10.1074/jbc.m412525200
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发表时间：
2005-03-11
影响因子：
4.8
通讯作者：
Tatzelt, J
中科院分区：
文献类型：
--
作者：
Kiachopoulos, S;Bracher, A;Tatzelt, J
细胞朊病毒蛋白（PrPC）的异常折叠是朊病毒疾病的一个关键特征。在这里，我们发现与人类遗传性朊病毒疾病相关的两种致病性突变严重影响神经元细胞分泌途径中PrPC的折叠和成熟。PrP-T183A和PrP-F198S采用错误折叠和部分蛋白酶抗性构象，缺乏糖基磷脂酰肌醇锚点，并且没有复杂糖基化。这些错误折叠的PrP突变体不会保留在内质网中，也不会受到内质网相关降解途径的影响。它们是分泌的，而且这些突变体可以被异源细胞内化。结构研究表明，Thr（183）和Phe（198）的侧链参与了PrPC c端球状结构域二级结构元之间的相互作用。因此，我们推断这些突变体的不稳定三级结构可以解释成熟缺陷。事实上，预测有选择地干扰PrPC疏水核心包装的突变阻止了糖基磷脂酰肌醇锚点的添加。我们的研究表明，PrPC的c端球形结构域的形成对膜锚定有影响，并表明错误折叠的朊病毒蛋白分泌形式与人类遗传性朊病毒疾病有关。
Abnormal folding of the cellular prion protein ( PrPC) is a key feature in prion diseases. Here we show that two pathogenic mutations linked to inherited prion diseases in humans severely affect folding and maturation of PrPC in the secretory pathway of neuronal cells. PrP-T183A and PrP-F198S adopt a misfolded and partially protease-resistant conformation, lack the glycosylphosphatidylinositol anchor, and are not complex glycosylated. These misfolded PrP mutants are not retained in the endoplasmic reticulum and are not subjected to the endoplasmic reticulum-associated degradation pathway. They rather are secreted, moreover, these mutants can be internalized by heterologous cells. Structural studies indicated that the side chains of Thr(183) and Phe(198) contribute to interactions between secondary structure elements in the C-terminal globular domain of PrPC. Consequently, we reasoned that a destabilized tertiary structure of these mutants could account for the defect in maturation. Indeed, mutations predicted to interfere selectively with the packing of the hydrophobic core of PrPC prevented the addition of the glycosylphosphatidylinositol anchor. Our study reveals that formation of the C-terminal globular domain of PrPC has an impact on membrane anchoring and indicates that misfolded secreted forms of the prion protein are linked to inherited prion diseases in humans.