Lyles D S, McKenzie M O, Hantgan R R
Department of Microbiology and Immunology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157-11064, USA.
Biochemistry. 1996 May 21;35(20):6508-18. doi: 10.1021/bi952001n.
During the process of assembly of enveloped viruses, binding of the nucleoprotein core of the virus (nucleocapsid) to the host membrane is mediated by the viral matrix (M) protein. Light scattering properties of vesicular stomatitis virus (VSV) nucleocapsids and nucleocapsid-M protein (NCM) complexes assembled in vivo were determined following solubilizaton of the virion envelope with detergents at varying ionic strength to vary the extent of M protein binding. Three factors were found to contribute to the light scattering properties of VSV nucleocapsids: their conformation, extent of self-association, and amount of bound M protein. All three were affected by changes in ionic strength but could be distinguished by several parameters. Conformational changes in nucleocapsids and NCM complexes occurred rapidly (millisecond time scale) upon changing salt concentration and were reflected in changes in the angular dependence of light scattering intensity (i.e., changes in radius of gyration, RG). Changes in extent of self-association occurred relatively slowly (seconds to minutes time scale) and could be distinguished by the concentration dependence of the apparent molecular mass and diffusion coefficient of the NCM complex. Changes in M protein binding occurred on an intermediate time scale (t1/2 approximately one s) and reflected changes in both molecular mass and RG. The data presented here provide criteria for assessing binding of M protein to nucleocapsids under conditions of minimal perturbation of the NCM complex assembled in vivo and at low protein concentrations so that self-association of the NCM complex was minimal and reversible.
在包膜病毒的组装过程中，病毒核蛋白核心（核衣壳）与宿主膜的结合由病毒基质（M）蛋白介导。在用去污剂在不同离子强度下溶解病毒包膜以改变M蛋白结合程度后，测定了在体内组装的水疱性口炎病毒（VSV）核衣壳和核衣壳-M蛋白（NCM）复合物的光散射特性。发现有三个因素有助于VSV核衣壳的光散射特性：它们的构象、自缔合程度和结合的M蛋白量。这三个因素均受离子强度变化的影响，但可通过几个参数加以区分。改变盐浓度时，核衣壳和NCM复合物的构象变化迅速（毫秒时间尺度），并反映在光散射强度的角度依赖性变化上（即回转半径RG的变化）。自缔合程度的变化发生得相对较慢（几秒到几分钟的时间尺度），可通过NCM复合物的表观分子量和扩散系数的浓度依赖性来区分。M蛋白结合的变化发生在中间时间尺度（半衰期约为1秒），反映了分子量和RG的变化。本文提供的数据为评估在体内组装的NCM复合物受到最小干扰且蛋白质浓度较低的条件下M蛋白与核衣壳的结合提供了标准，从而使NCM复合物的自缔合最小且可逆。
