Solution structure of a 142-residue recombinant prion protein corresponding to the infectious fragment of the scrapie isoform
Solution structure of a 142-residue recombinant prion protein corresponding to the infectious fragment of the scrapie isoform
复制标题
DOI：
10.1073/pnas.94.19.10086
复制
发表时间：
1997-09-16
影响因子：
11.1
通讯作者：
Cohen, FE
中科院分区：
文献类型：
--
作者：
James, TL;Liu, H;Cohen, FE
羊瘙痒症朊蛋白（PrPSc）是感染性朊蛋白的主要成分，也可能是唯一的成分;它是由细胞同种型（PrPC）通过构象变化产生的。通过限制性蛋白酶解将PrPSc的N端截短，得到约142个残基的PrP 27-30蛋白，该蛋白保留了感染性。在大肠杆菌中表达并纯化了与叙利亚仓鼠PrP 27-30相对应的重组蛋白（rPrP）。揭示了rPrP的许多结构特征，这些结构特征在先前研究的两个较短的PrP片段中没有发现。残基113-125的广泛的侧链相互作用表征了疏水簇，其与不规则的β-片层堆积，而残基90-112表现出很少确定的结构。尽管可识别的二级结构在rPrP的N末端中很大程度上缺乏，但矛盾的是，该N末端增加了rPrP的其余部分中的二级结构的量。（残基200-227）和结构化环（残基165-171）形成用于结合促进PrPSc形成的蛋白质的不连续表位，该表位内的多态性残基似乎调节绵羊和人类对朊病毒疾病的易感性。rPrP在N端的构象异质性可能是PrPC转化为PrPSc的关键，而C端附近的不连续表位控制着这种转变。
The scrapie prion protein (PrPSc) is the major, and possibly the only, component of the infectious prion; it is generated from the cellular isoform (PrPC) by a conformational change. N-terminal truncation of PrPSc by limited proteolysis produces a protein of approximate to 142 residues designated PrP 27-30, which retains infectivity, A recombinant protein (rPrP) corresponding to Syrian hamster PrP 27-30 was expressed in Escherichia coli and purified, After refolding rPrP into an alpha-helical form resembling PrPC, the structure was solved by multidimensional heteronuclear NMR, revealing many structural features of rPrP that were not found in two shorter PrP fragments studied previously, Extensive side-chain interactions for residues 113-125 characterize a hydrophobic cluster, which packs against an irregular beta-sheet, whereas residues 90-112 exhibit little defined structure. Although identifiable secondary structure is largely lacking in the N terminus of rPrP, paradoxically this N terminus increases the amount of secondary structure in the remainder of rPrP, The surface of a long helix (residues 200-227) and a structured loop (residues 165-171) form a discontinuous epitope for binding of a protein that facilitates PrPSc formation, Polymorphic residues within this epitope seem to modulate susceptibility of sheep and humans to prion disease. Conformational heterogeneity of rPrP at the N terminus may be key to the transformation of PrPC into PrPSc, whereas the discontinuous epitope near the C terminus controls this transition.