Structure of the carboxy-terminal receptor-binding domain of avian reovirus fibre SigmaC
Structure of the carboxy-terminal receptor-binding domain of avian reovirus fibre SigmaC
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DOI：
10.1016/j.jmb.2005.09.034
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发表时间：
2005-11-18
影响因子：
5.6
通讯作者：
van Raaij, MJ
中科院分区：
文献类型：
--
作者：
Calvo, PG;Fox, GC;van Raaij, MJ
禽呼肠孤病毒纤维是 sigmaC 蛋白的同源三聚体，负责初级宿主细胞的附着。细菌中表达的蛋白质形成由羧基端球状头结构域和细长轴组成的细长纤维，部分蛋白水解产生易于结晶的羧基端蛋白酶稳定结构域。在这里，我们证明该片段保留了受体结合能力并报告了其结构，使用双波长异常衍射进行了解析，并使用从三种不同晶型以 2.1 埃、2.35 埃和 3.0 埃分辨率收集的数据进行了精炼。羧基末端球状结构域具有与哺乳动物呼肠孤病毒纤维 (sigma1) 相同的整体拓扑结构的 β 桶形结构。然而，sigmaC 三聚体的单体表现出比 sigmal 结构更加展开的排列。还解决了轴或茎域的两个三重β螺旋重复。这些三重β-螺旋重复序列氨基末端的七肽重复序列中的存在表明轴结构域的未解析部分包含三重α-螺旋卷曲螺旋结构。讨论了 sigmaC 蛋白的功能和稳定性的影响。 (c) 2005 Elsevier Ltd. 保留所有权利。
Avian reovirus fibre, a homo-trimer of the sigmaC protein, is responsible for primary host cell attachment. The protein expressed in bacteria forms elongated fibres comprised of a carboxy-terminal globular head domain and a slender shaft, and partial proteolysis yielded a carboxy-terminal protease-stable domain that was amenable to crystallisation. Here, we show that this fragment retains receptor-binding capability and report its structure, solved using two-wavelength anomalous diffraction and refined using data collected from three different crystal forms at 2.1 angstrom, 2.35 angstrom and 3.0 angstrom resolution. The carboxy-terminal globular domain has a beta-barrel fold with the same overall topology as the mammalian reovirus fibre (sigma1). However, the monomers of the sigmaC trimer show a more splayed-out arrangement than in the sigmal structure. Also resolved are two triple beta-spiral repeats of the shaft or stalk domain. The presence in the sequence of heptad repeats amino-terminal to these triple beta-spiral repeats suggests that the unresolved portion of the shaft domain contains a triple alpha-helical coiled-coil structure. Implications for the function and stability of the sigmaC protein are discussed. (c) 2005 Elsevier Ltd. All rights reserved.