Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111 , USA.
J Virol. 2010 May;84(10):4923-35. doi: 10.1128/JVI.00206-10. Epub 2010 Mar 3.
The cytoplasmic domain of glycoprotein B (gB) from herpes simplex virus type 1 (HSV-1) is an important regulator of membrane fusion. C-terminal truncations of the cytoplasmic domain lead to either hyperfusion or fusion-null phenotypes. Currently, neither the structure of the cytoplasmic domain nor its mechanism of fusion regulation is known. Here we show, for the first time, that the full-length cytoplasmic domain of HSV-1 gB associates stably with lipid membranes, preferentially binding to membranes containing anionic head groups. This interaction involves a large increase in helical content. However, the truncated cytoplasmic domains associated with the hyperfusion phenotype show a small increase in helical structure and a diminished association with lipid membranes, whereas the one associated with the fusion-null phenotype shows no increase in helical structure and only a minimal association with lipid membranes. We hypothesize that stable binding to lipid membranes is an important part of the mechanism by which the cytoplasmic domain negatively regulates membrane fusion. Moreover, our experiments with truncated cytoplasmic domains point to two specific regions that are critical for membrane interactions. Taken together, our work provides several important new insights into the architecture of the cytoplasmic domain of HSV-1 gB and its interaction with lipid membranes.
单纯疱疹病毒 1 型（HSV-1）糖蛋白 B（gB）的细胞质结构域是膜融合的重要调节剂。细胞质结构域的 C 端截断导致超融合或融合缺失表型。目前，细胞质结构域的结构及其融合调节机制尚不清楚。在这里，我们首次表明，HSV-1 gB 的全长细胞质结构域与脂质膜稳定结合，优先结合含有阴离子头基的膜。这种相互作用涉及到螺旋结构含量的大幅增加。然而，与超融合表型相关的截断的细胞质结构域显示出螺旋结构的小幅度增加和与脂质膜的结合减少，而与融合缺失表型相关的结构域则没有螺旋结构的增加，与脂质膜的结合也很少。我们假设与脂质膜的稳定结合是细胞质结构域负调控膜融合机制的重要组成部分。此外，我们用截断的细胞质结构域进行的实验指出了两个与膜相互作用至关重要的特定区域。总之，我们的工作为 HSV-1 gB 的细胞质结构域的结构及其与脂质膜的相互作用提供了几个重要的新见解。
