“人免疫缺陷病毒-1” (HIV-1)的病毒颗粒有一个锥形的核，由衣壳蛋白组成，后者要么是五聚体，要么是六聚体。Mark Yeager及其同事以前曾确定了衣壳蛋白六聚体的晶体结构。现在，他们提供了五聚体的结构，这使他们能够提出成熟HIV衣壳的首个原子层面的模型。（生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature09640
Atomic-level modelling of the HIV capsid
Owen Pornillos,Barbie K. Ganser-Pornillos& Mark Yeager
The mature capsids of human immunodeficiency virus type 1 (HIV-1) and other retroviruses are fullerene shells, composed of the viral CA protein, that enclose the viral genome and facilitate its delivery into new host cells1. Retroviral CA proteins contain independently folded amino (N)- and carboxy (C)-terminal domains (NTD and CTD) that are connected by a flexible linker2, 3, 4. The NTD forms either hexameric or pentameric rings, whereas the CTD forms symmetric homodimers that connect the rings into a hexagonal lattice3, 5, 6, 7, 8, 9, 10, 11, 12, 13. We previously used a disulphide crosslinking strategy to enable isolation and crystallization of soluble HIV-1 CA hexamers11, 14. Here we use the same approach to solve the X-ray structure of the HIV-1 CA pentamer at 2.5?? resolution. Two mutant CA proteins with engineered disulphides at different positions (P17C/T19C and N21C/A22C) converged onto the same quaternary structure, indicating that the disulphide-crosslinked proteins recapitulate the structure of the native pentamer. Assembly of the quasi-equivalent hexamers and pentamers requires remarkably subtle rearrangements in subunit interactions, and appears to be controlled by an electrostatic switch that favours hexamers over pentamers. This study completes the gallery of substructures describing the components of the HIV-1 capsid and enables atomic-level modelling of the complete capsid. Rigid-body rotations around two assembly interfaces appear sufficient to generate the full range of continuously varying lattice curvature in the fullerene cone.
