Assembly properties of the human immunodeficiency virus type 1 CA protein
Assembly properties of the human immunodeficiency virus type 1 CA protein
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DOI：
10.1128/jvi.78.5.2545-2552.2004
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发表时间：
2004-03-01
影响因子：
5.4
通讯作者：
Sundquist, WI
中科院分区：
文献类型：
--
作者：
Ganser-Pornillos, BK;von Schwedler, UK;Sundquist, WI
在逆转录病毒成熟过程中，CA蛋白寡聚形成一个封闭的衣壳，包裹着病毒基因组。我们之前已经在人类免疫缺陷病毒1型（HIV-1） CA中发现了一系列有害的表面突变，这些突变可以改变体内的传染性、复制和组装。在这项研究中，27个含有34种不同突变的重组CA蛋白在体外组装成螺旋柱的能力进行了测试。这些圆柱体由CA六聚体组成，是成熟病毒衣壳的结构模型。减少CA组装的突变聚集在CA的n端结构域的1和2螺旋内，以及CA的c端结构域的晶体学定义的二聚体界面内。这些突变证明了这些区域对CA圆筒的产生以及类似的成熟衣壳组装的重要性。一个CA突变体（R18A）组装成圆柱体、锥体和球体。我们认为这些衣壳形状的发生是因为R18A突变改变了五聚体融入六边形晶格的频率。一个单一的CA蛋白可以同时形成所有三种已知的逆转录病毒衣壳形态，这一事实支持了这样一种观点，即这些结构是在相似的晶格上组织的，不同的只是12个五聚体的分布，这些五聚体允许它们闭合。为了进一步支持这一模型，我们证明了锥形HIV-1衣壳的相当大的形态变化可以通过改变五聚体的分布在理想化的衣壳模型中重现。
During retroviral maturation, the CA protein oligomerizes to form a closed capsid that surrounds the viral genome. We have previously identified a series of deleterious surface mutations within human immunodeficiency virus type 1 (HIV-1) CA that alter infectivity, replication, and assembly in vivo. For this study, 27 recombinant CA proteins harboring 34 different mutations were tested for the ability to assemble into helical cylinders in vitro. These cylinders are composed of CA hexamers and are structural models for the mature viral capsid. Mutations that diminished CA assembly clustered within helices 1 and 2 in the N-terminal domain of CA and within the crystallographically defined dimer interface in the CA C-terminal domain. These mutations demonstrate the importance of these regions for CA cylinder production and, by analogy, mature capsid assembly. One CA mutant (R18A) assembled into cylinders, cones, and spheres. We suggest that these capsid shapes occur because the R18A mutation alters the frequency at which pentamers are incorporated into the hexagonal lattice. The fact that a single CA protein can simultaneously form all three known retroviral capsid morphologies supports the idea that these structures are organized on similar lattices and differ only in the distribution of 12 pentamers that allow them to close. In further support of this model, we demonstrate that the considerable morphological variation seen for conical HIV-1 capsids can be recapitulated in idealized capsid models by altering the distribution of pentamers.