Li S, Hill C P, Sundquist W I, Finch J T
Department of Biochemistry, University of Utah, Salt Lake City 84132, USA.
Nature. 2000 Sep 21;407(6802):409-13. doi: 10.1038/35030177.
The type 1 human immunodeficiency virus (HIV-1) contains a conical capsid comprising approximately 1,500 CA protein subunits, which organizes the viral RNA genome for uncoating and replication in a new host cell. In vitro, CA spontaneously assembles into helical tubes and cones that resemble authentic viral capsids. Here we describe electron cryo-microscopy and image reconstructions of CA tubes from six different helical families. In spite of their polymorphism, all tubes are composed of hexameric rings of CA arranged with approximate local p6 lattice symmetry. Crystal structures of the two CA domains were 'docked' into the reconstructed density, which showed that the amino-terminal domains form the hexameric rings and the carboxy-terminal dimerization domains connect each ring to six neighbours. We propose a molecular model for the HIV-1 capsid that follows the principles of a fullerene cone, in which the body of the cone is composed of curved hexagonal arrays of CA rings and the ends are closed by inclusion of 12 pentagonal 'defects'.
1型人类免疫缺陷病毒（HIV-1）包含一个由大约1500个CA蛋白亚基组成的锥形衣壳，该衣壳将病毒RNA基因组组织起来以便在新宿主细胞中脱壳和复制。在体外，CA能自发组装成类似于真实病毒衣壳的螺旋管和锥体。在此，我们描述了来自六个不同螺旋家族的CA管的电子低温显微镜观察及图像重建。尽管它们具有多态性，但所有的管都是由具有近似局部p6晶格对称性排列的CA六聚体环组成。将两个CA结构域的晶体结构“对接”到重建密度中，结果表明氨基末端结构域形成六聚体环，而羧基末端二聚化结构域将每个环与六个相邻环相连。我们提出了一个遵循富勒烯锥体原理的HIV-1衣壳分子模型，其中锥体主体由CA环的弯曲六边形阵列组成，其末端通过包含12个五边形“缺陷”而封闭。
