Prion strain-dependent differences in conversion of mutant prion proteins in cell culture
Prion strain-dependent differences in conversion of mutant prion proteins in cell culture
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DOI：
10.1128/jvi.00424-06
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发表时间：
2006-08-01
影响因子：
5.4
通讯作者：
Katamine, Shigeru
中科院分区：
文献类型：
--
作者：
Atarashi, Ryuichiro;Sim, Valerie L.;Katamine, Shigeru
尽管纯蛋白质假说认为决定菌株多样性的是异常蛋白构象(PrPSc)，但菌株的分子基础仍有待阐明。在本研究中，我们在正常PrPC蛋白(PrPC)中产生了一系列突变，其中单个谷氨酰胺残基被碱性氨基酸取代，并比较了它们在感染Chandler或22L小鼠适应的瘙痒病菌株的培养神经元N2a58细胞中转换为PrPSc的能力。根据红外光谱的判断，在小鼠体内，这些菌株产生的PrPSc序列相同，但构象不同。第97、167、171和216位密码子的替换产生了PrPC，在Chandler感染和22L感染的细胞中，PrPC抵抗转换并抑制共表达的野生型PrP的转换。有趣的是，第185和218密码子的替换产生了依赖于菌株的效应。Q185R和Q185K PrP在Chandler感染的细胞中有效地转化为PrPSc，而在22L感染的细胞中不能转化为PrPSc。相反，Q218R和Q218H PrP仅在22L感染的细胞中被转换。此外，Q218K PrP对共表达的野生型PrP在Chandler感染细胞中的转化有很强的抑制作用，而对22L感染细胞的作用不明显。这些结果表明，两株PrP序列相同但构象不同的菌株转化相同突变的PrPC的能力不同。
Although the protein-only hypothesis proposes that it is the conformation of abnormal prion protein (PrPSc) that determines strain diversity, the molecular basis of strains remains to be elucidated. In the present study, we generated a series of mutations in the normal prion protein (PrPC) in which a single glutamine residue was replaced with a basic amino acid and compared their abilities to convert to PrPSc in cultured neuronal N2a58 cells infected with either the Chandler or 22L mouse-adapted scrapie strain. In mice, these strains generate PrPSc of the same sequence but different conformations, as judged by infrared spectroscopy. Substitutions at codons 97, 167, 171, and 216 generated PrPC that resisted conversion and inhibited the conversion of coexpressed wild-type PrP in both Chandler-infected and 22L-infected cells. Interestingly, substitutions at codons 185 and 218 gave strain-dependent effects. The Q185R and Q185K PrP were efficiently converted to PrPSc in Chandler-infected but not 22L-infected cells. Conversely, Q218R and Q218H PrP were converted only in 22L-infected cells. Moreover, the Q218K PrP exerted a potent inhibitory effect on the conversion of coexpressed wild-type PrP in Chandler-infected cells but had little effect on 22L-infected cells. These results show that two strains with the same PrP sequence but different conformations have differing abilities to convert the same mutated PrPC.