Howard M, Wertz G
Department of Microbiology and Immunology, Medical School, University of North Carolina, Chapel Hill 27514.
J Gen Virol. 1989 Oct;70 ( Pt 10):2683-94. doi: 10.1099/0022-1317-70-10-2683.
Synthesis of the vesicular stomatitis virus nucleocapsid (N) protein is required for viral RNA replication. The observation that the N protein forms a rapidly sedimenting species in the absence of other viral proteins and the description of complexes of N protein with NS protein led to the proposal that NS protein binds to N protein to prevent it from self-associating. We tested this model by analysing the physical properties of N protein synthesized alone in an in vitro replication system as compared to N protein synthesized in the presence of the NS protein. These findings were correlated with the ability of the N protein, synthesized under both conditions, to support replication. N protein synthesized at low concentrations in the absence of other viral proteins sedimented at 4S on glycerol gradients and was capable of supporting RNA replication. In contrast, synthesis of increasing concentrations of N protein resulted in formation of a rapidly sedimenting species of N protein which had the physical properties of a protein-protein aggregate and which failed to support RNA replication. Co-synthesis of the NS protein with N protein both prevented the concentration-dependent aggregation of N and restored the ability of high concentrations of N protein to support RNA replication.
水泡性口炎病毒核衣壳（N）蛋白的合成是病毒RNA复制所必需的。N蛋白在没有其他病毒蛋白的情况下形成快速沉降的物种，以及N蛋白与NS蛋白复合物的描述，导致有人提出NS蛋白与N蛋白结合以防止其自我缔合。我们通过分析在体外复制系统中单独合成的N蛋白与在NS蛋白存在下合成的N蛋白的物理性质来测试这个模型。这些发现与在两种条件下合成的N蛋白支持复制的能力相关。在没有其他病毒蛋白的情况下，低浓度合成的N蛋白在甘油梯度上以4S沉降，并且能够支持RNA复制。相反，合成浓度不断增加的N蛋白导致形成一种快速沉降的N蛋白物种，其具有蛋白质-蛋白质聚集体的物理性质，并且不能支持RNA复制。NS蛋白与N蛋白共同合成既防止了N的浓度依赖性聚集，又恢复了高浓度N蛋白支持RNA复制的能力。
