MOLECULAR-STRUCTURE OF THE CELL-ATTACHMENT PROTEIN OF REOVIRUS - CORRELATION OF COMPUTER-PROCESSED ELECTRON-MICROGRAPHS WITH SEQUENCE-BASED PREDICTIONS
MOLECULAR-STRUCTURE OF THE CELL-ATTACHMENT PROTEIN OF REOVIRUS - CORRELATION OF COMPUTER-PROCESSED ELECTRON-MICROGRAPHS WITH SEQUENCE-BASED PREDICTIONS
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DOI：
10.1128/jvi.64.6.2990-3000.1990
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发表时间：
1990-06-01
影响因子：
5.4
通讯作者：
STEVEN, AC
中科院分区：
文献类型：
--
作者：
FRASER, RDB;FURLONG, DB;STEVEN, AC
启动呼肠孤病毒感染的受体-识别相互作用是由位于二十面体病毒粒子顶点的sigma 1蛋白介导的。我们已经应用基于计算机的图像平均技术对从病毒粒子（血清型2琼斯）中纯化的sigma 1负染色制剂的电子显微照片进行了处理。将这些结果与基于氨基酸序列的推断相结合，得出了一个分子模型，其中描述了链的整体折叠；它的构象体现了图案，卷曲的。-螺旋和结核多链元素富含- β。先前在其他病毒的相应蛋白质中检测到，但有一些新的变异。Sigma 1是一种丝状的棒棒糖状分子，其总长度约为。48海里;它有一个灵活的“尾巴”。apprx。长约40纳米，宽约40纳米，在远端终止于一个球状的“头”。直径9.5纳米。纯化的蛋白质是一个四聚体（4 × 50千道尔顿），由两个相似取向的二聚体并排结合并在寄存器中组成。对于每条链，在其氨基端有一簇疏水残基位于其尾部的近端；接下来是。alpha。-螺旋结构域（残基25 ~ 172）参与一个长22纳米的双链卷曲线圈，两个这样的卷曲线圈横向配对形成尾部的近半部。尾巴的剩余部分（残差为173 ~ 0.0.0.99）。316)在宽度上不太均匀，预计在.beta.-sheet中丰富；中间二聚体键显然通过分子的这一部分得以维持。最后，球状头由羧基末端结构域（包含受体结合位点）折叠成紧密的球状构象组成；在适当的侧面视图中，头被分解成两个亚单位，可能是由各自的二聚体贡献的。这个模型是如何。1多肽链在纤维中平行穿过，通过观察到的经验曲率曲线与基于模型预测的柔韧性曲线之间的匹配来支持。经验曲率曲线识别了沿纤维尾部相对柔韧性位点的位置。对稳定盘绕线圈的相互作用的评估表明(i)。-螺旋单独只有边际稳定，这一特性对于完整病毒粒子中容纳sigma 1的收缩构象可能具有重要意义，并且（ii）两个卷曲线圈之间的主要相互作用可能涉及未带电残基斑块之间的氢键。
The receptor-recognition interaction that initiates reovirus infection is mediated by the sigma 1 protein, located at the vertices of the icosahedral virion. We have applied computer-based image-averaging techniques to electron micrographs of negatively stained preparations of sigma 1 purified from virions (serotype 2 Jones). Combining these results with inferences based on the amino acid sequence has led to a molecular model in which the overall folding of the chains is described; its conformation embodies motifs, coiled-coil .alpha.-helices and nodular multichain elements rich in .beta.-sheets, previously detected in the corresponding proteins of other viruses, but with some novel variations. Sigma 1 is a filamentous lollipop-shaped molecule with an overall length of .apprx. 48 nm; it has a flexible "tail," .apprx. 40 nm long by nm wide, terminating at its distal end in a globular "head," .apprx. 9.5 nm in diameter. The purified protein is a tetramer (4 by 50 kilodaltons) consisting of two similarly oriented dimers bonded side by side and in register. For each chain, a cluster of hydrophobic residues at its amino terminus resides at the proximal end of the tail; next, an .alpha.-helical domain (residues 25 to 172) participates in a two-chained coiled coil, 22 nm long, with two such coiled coils pairing laterally to form the proximal half of the tail. The remainder of the tail (residues 173 to .apprx. 316) is less uniform in width and is expected to be rich in .beta.-sheet; the interdimer bonding is evidently sustained through this portion of the molecule. Finally, the globular head consists of the carboxy-terminal domains (which contain the receptor-binding sites) folded into compact globular conformations; in appropriate side views, the head is resolved into two subunits, presumably contributed by the respective dimers. This model for how the four .sigma.1 polypeptide chains are threaded in parallel through the fiber is supported by the observed match between an empirical curvature profile, which identified the locations of relatively flexible sites along the tail, and the flexibility profile predicted on the basis of the model. Appraisal of the interactions that stabilize the coiled coils suggests that (i) the .alpha.-helices are individually only marginally stable, a property that may be of significance with regard to the retracted conformation in which sigma 1 is accommodated in the intact virion, and (ii) the predominant interactions between the two coiled coils are likely to involve hydrogen bonding between patches of uncharged residues.