Molecular structures of viruses from Raman optical activity
Molecular structures of viruses from Raman optical activity
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DOI：
10.1099/0022-1317-83-10-2593
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发表时间：
2002-10-01
影响因子：
3.8
通讯作者：
Barron, LD
中科院分区：
文献类型：
--
作者：
Blanch, EW;Hecht, L;Barron, LD
一系列不同结构类型的病毒的振动拉曼光学活性（罗阿）的研究，例如丝状噬菌体fd，烟草花叶病毒，卫星烟草花叶病毒，噬菌体MS 2和豇豆花叶病毒已揭示，由于其对手性的敏感性，罗阿是一个敏锐的探针，其水溶液的结构在分子水平上。蛋白质罗阿带是特别突出的，正如我们通过与已知结构的蛋白质的罗阿光谱的比较以及通过使用模式识别程序所示，可以从其推断出主要外壳蛋白亚基的折叠。有时也可以获得关于氨基酸侧链构象的信息，这里通过测定fd中色氨酸的扭转角chi（2，1）的符号和大小来举例说明。用氯化铯密度梯度法分离豇豆花叶病毒的中部和底部-上部组分，再减去其空蛋白衣壳（顶部组分）的罗阿光谱，得到豇豆花叶病毒RNA的罗阿光谱。结果表明，豇豆花叶病毒RNA呈A型单链螺旋构象，中部和底部-上部组分的RNA构象非常相似。这一信息不能从豇豆花叶病毒的X射线晶体结构中获得，因为没有可见的核酸。
A vibrational Raman optical activity (ROA) study of a range of different structural types of virus exemplified by filamentous bacteriophage fd, tobacco mosaic virus, satellite tobacco mosaic virus, bacteriophage MS2 and cowpea mosaic virus has revealed that, on account of its sensitivity to chirality, ROA is an incisive probe of their aqueous solution structures at the molecular level. Protein ROA bands are especially prominent from which, as we have shown by comparison with the ROA spectra of proteins with known structures and by using a pattern recognition program, the folds of the major coat protein subunits may be deduced. Information about amino acid side-chain conformations, exemplified here by the determination of the sign and magnitude of the torsion angle chi(2,1) for tryptophan in fd, may also sometimes be obtained. By subtracting the ROA spectrum of the empty protein capsid (top component) of cowpea mosaic virus from those of the intact middle and bottom-upper components separated by means of a caesium chloride density gradient, the ROA spectrum of the viral RNA was obtained, which revealed that the RNA takes up an A-type single-stranded helical conformation and that the RNA conformations in the middle and bottom-upper components are very similar. This information is not available from the X-ray crystal structure of cowpea mosaic virus since no nucleic acid is visible.