Identifying Key Components of the PrPC-PrPSc Replicative Interface
Identifying Key Components of the PrPC-PrPSc Replicative Interface
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DOI：
10.1074/jbc.m804475200
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发表时间：
2008-12-05
影响因子：
4.8
通讯作者：
Solforosi, Laura
中科院分区：
文献类型：
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作者：
Abalos, Gil C.;Cruite, Justin T.;Solforosi, Laura
在朊病毒疾病中，细胞朊病毒蛋白（PrPC）与其错误折叠的疾病相关构象蛋白PrPSc之间的直接相互作用是促进新生PrPSc形成和朊病毒感染性的关键步骤，尽管了解甚少。最近，我们假设PrP的三个区域（对应于氨基酸残基23-33，98-110和136-158）与PrPSc特异性和鲁棒性相互作用，可能代表朊病毒复制界面一侧的肽组分。在这项研究中，我们创建了表位标记的小鼠PrPC分子，其中PrP序列23-33，98-110和136-158被修饰。这些新的PrP分子分别在朊病毒感染的神经母细胞瘤细胞系（ScN 2a）和转换的每个突变的小鼠PrPC基板PrPSc相比，表位标记的野生型小鼠PrPC。PrP 98-110内的突变，用丙氨酸残基取代所有4个野生型赖氨酸残基，阻止转化为PrPSc。此外，当PrP 136 - 140内的残基被集体打乱，变为丙氨酸，或位置136、137和139处的氨基酸被丙氨酸单独取代时，类似地停止向PrPSc的转化。然而，在区域23-33和101-104内含有突变的其他PrP分子能够容易地转化为PrPSc。这些结果表明，包含残基98-110和136-140的PrP序列不仅参与PrPC和PrPSc之间的特异性结合相互作用，而且还参与导致PrPSc螯合的PrPC转化为其疾病相关形式的过程。
In prion disease, direct interaction between the cellular prion protein (PrPC) and its misfolded disease-associated conformer PrPSc is a crucial, although poorly understood step promoting the formation of nascent PrPSc and prion infectivity. Recently, we hypothesized that three regions of PrP (corresponding to amino acid residues 23-33, 98-110, and 136-158) interacting specifically and robustly with PrPSc, likely represent peptidic components of one flank of the prion replicative interface. In this study, we created epitope-tagged mouse PrPC molecules in which the PrP sequences 23-33, 98-110, and 136-158 were modified. These novel PrP molecules were individually expressed in the prion-infected neuroblastoma cell line (ScN2a) and the conversion of each mutated mouse PrPC substrate to PrPSc compared with that of the epitope-tagged wild-type mouse PrPC. Mutations within PrP 98-110, substituting all 4 wild-type lysine residues with alanine residues, prevented conversion to PrPSc. Furthermore, when residues within PrP 136 140 were collectively scrambled, changed to alanines, or amino acids at positions 136, 137, and 139 individually replaced by alanine, conversion to PrPSc was similarly halted. However, other PrP molecules containing mutations within regions 23-33 and 101-104 were able to readily convert to PrPSc. These results suggest that PrP sequence comprising residues 98-110 and 136-140 not only participates in the specific binding interaction between PrPC and PrPSc, but also in the process leading to conversion of PrPSc-sequestered PrPC into its disease-associated form.