Protease cleavage of reovirus capsid protein mu 1/mu 1C is blocked by alkyl sulfate detergents, yielding a new type of infectious subvirion particle
Protease cleavage of reovirus capsid protein mu 1/mu 1C is blocked by alkyl sulfate detergents, yielding a new type of infectious subvirion particle
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DOI：
10.1128/jvi.72.1.467-475.1998
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发表时间：
1998-01-01
影响因子：
5.4
通讯作者：
Nibert, ML
中科院分区：
文献类型：
--
作者：
Chandran, K;Nibert, ML
哺乳动物呼肠孤病毒病毒粒子在体外暴露于蛋白酶时经历外衣壳的部分解体，产生感染性亚病毒粒子颗粒（ISVP），其缺乏蛋白σ 3并含有蛋白μ 1/μ 1C作为内切蛋白酶产生的片段μ 1 δ/δ和φ。ISVP被认为是呼肠孤病毒感染的两个早期步骤所必需的：膜渗透和颗粒结合的病毒转录酶复合物的激活。遗传和生物化学证据表明外衣壳蛋白yl参与了这两个步骤。为了确定mu 1/mu 1C的裂解是否与ISVP的独特性质相关，我们分析了缺乏σ 3但保留mu 1/mu 1C的未裂解但可裂解形式的新型亚病毒粒子的性质。这些洗涤剂加蛋白酶亚病毒粒子（dpSVP）是通过在烷基硫酸盐洗涤剂的胶束形成浓度存在下用胰凝乳蛋白酶处理病毒粒子而产生的。在鼠L或犬MDCK细胞中用dpSVP感染提供的证据表明，在病毒进入这些细胞期间mu 1/mu 1C的裂解对于呼肠孤病毒感染是不稳定的。此外，dpSVP在其透化脂质双层和体外转录酶活化的能力方面表现得像ISVP，支持病毒进入期间mu 1/mu 1C裂解为mu 1 delta/delta和phi对于细胞中的膜穿透或转录酶活化都不是必需的结论。烷基硫酸盐洗涤剂以可逆方式抑制mu 1/mu 1C裂解的能力表明病毒颗粒和洗涤剂胶束之间存在特异性关联，其可能在呼肠孤病毒进入细胞期间模拟病毒颗粒-磷脂膜相互作用。
Mammalian reovirus virions undergo partial disassembly of the outer capsid upon exposure to proteases in vitro, producing infectious subvirion particles (ISVPs) that lack protein sigma 3 and contain protein mu 1/mu 1C as endoprotease-generated fragments mu 1 delta/delta and phi. ISVPs are thought to be required for two early steps in reovirus infection: membrane penetration and activation of the particle-bound viral transcriptase complexes. Genetic and biochemical evidence implicates outer-capsid protein yl in both these steps. To determine whether the cleavage of mu 1/mu 1C is relevant to the unique properties of ISVPs, we analyzed the properties of novel subvirion particles that lacked sigma 3 yet retained mu 1/mu 1C in an uncleaved but cleavable form. These detergent-plus-protease subvirion particles (dpSVPs) were produced by treating virions with chymotrypsin in the presence of micelle-forming concentrations of alkyl sulfate detergents. Infections with dpSVPs in murine L or canine MDCK cells provided evidence that the cleavage of mu 1/mu 1C during viral entry into these cells is dispensable for reovirus infection. Additionally, dpSVPs behaved like ISVPs in their capacity to permeabilize lipid bilayers and to undergo transcriptase activation in vitro, supporting the conclusion that cleavage of mu 1/mu 1C to mu 1 delta/delta and phi during viral entry is not required for either membrane penetration or transcriptase activation in cells. The capacity of alkyl sulfate detergents to inhibit the cleavage of mu 1/mu 1C in a reversible fashion suggests a specific association between virus particle and detergent micelles that may mimic virus particle-phospholipid membrane interactions during reovirus entry into cells.