Crystal Structure of Herpes Simplex Virus 2 gD Bound to Nectin-1 Reveals a Conserved Mode of Receptor Recognition
Crystal Structure of Herpes Simplex Virus 2 gD Bound to Nectin-1 Reveals a Conserved Mode of Receptor Recognition
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DOI：
10.1128/jvi.01906-14
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发表时间：
2014-12-01
影响因子：
5.4
通讯作者：
Yan, Jinghua
中科院分区：
文献类型：
--
作者：
Lu, Guangwen;Zhang, Na;Yan, Jinghua
单纯疱疹病毒1型(HSV-1)和单纯疱疹病毒2型(HSV-2)是人类最常见的病原体。这两种病毒都可以通过表面包膜糖蛋白D(GD)识别作为功能性受体的人Nextin-1。以往的研究已经成功地用共结晶学方法阐明了HSV-1 gD与Nectin-1结合的分子基础。尽管HSV-1和HSV-2 GDS之间有很高的序列同源性，但HSV-2-gD/Nectin-1相互作用的原子分子间细节仍然难以捉摸。在这里，我们报道了未结合和Nectin-1结合的HSV-2 GDS的晶体结构。如HSV-1中观察到的那样，Free-Gd结构预期包括IGV样的核心和暴露在表面的末端延伸部分，但缺乏大部分末端元素的可追踪电子密度。这些末端残基在复杂的结构中被清晰地追踪为N末端的最终环和C末端的α螺旋，从而显示出与HSV-1GD相同的保守的Nextin-1结合模式。Nectin-1中的界面残基被进一步突变，并通过表面等离子体共振检测其与GD的相互作用。得到的HSV-1和HSV-2 GDS的结合模式相似，进一步支持了这两种病毒与Nectin-1的同源受体结合基础。这些数据，以及基于细胞的融合实验表明，可溶性HSV-1和HSV-2 GDS交叉抑制了GD/Nectin-1介导的细胞-细胞融合，为HSV-1和HSV-2通过相同的结合模式识别Nectin-1提供了坚实的结构和功能证据。最后，我们还证明了Nectin-1 I80是参与GD相互作用的一个重要残基。重要的是，尽管研究深入，但还没有关于HSV-2-GD/Nectin-1相互作用的详细分子特征的图像。以前的工作集中在HSV-1 gD上，它折叠成一个具有大末端延伸的IGV样核心，并利用延伸元件与Nectin-1结合。在这里，我们报道了HSV-2 gD的游离态和Nectin-1结合态的晶体结构。给出了HSV-2-Gd/Nectin-1相互作用的原子分子间细节。观察到的结合模式与已报道的HSV-1的结合模式相同。我们的比较功能分析进一步支持了这一结构观察，表明Nectin-1突变类似地影响两种病毒GDS的配体-受体相互作用。综上所述，我们提供了全面的结构和功能数据，证明了Nectin-1在HSV-1和HSV-2之间存在保守的受体结合模式。我们的结果还表明，这两种病毒之间的趋向性差异可能来自于GD/Nectin-1结合特征以外的其他方面。
Herpes simplex virus 1 (HSV-1) and HSV-2 are among the most prevalent human pathogens. Both viruses can recognize, via the surface envelope glycoprotein D (gD), human nectin-1 as a functional receptor. Previous studies have successfully elucidated the molecular basis of the binding between HSV-1 gD and nectin-1 by cocrystallography. Despite a high sequence identity between HSV-1 and HSV-2 gDs, the atomic intermolecule details for the HSV-2-gD/nectin-1 interaction remain elusive. Here, we report the crystal structures of both the unbound and the nectin-1-bound HSV-2 gDs. The free-gD structure expectedly comprises an IgV-like core and the surface-exposed terminal extensions as observed in its HSV-1 counterpart but lacks traceable electron densities for a large portion of the terminal elements. These terminal residues were clearly traced in the complex structure as a definitive loop in the N terminus and an alpha-helix in the C terminus, thereby showing a conserved nectin-1-binding mode as reported for HSV-1 gD. The interface residues in nectin-1 were further mutated and tested for the gD interaction by surface plasmon resonance. The resultant binding patterns were similar for HSV-1 and HSV-2 gDs, further supporting a homologous receptor-binding basis by the two viruses for nectin-1. These data, together with a cell-based fusion assay showing a cross-inhibition of the gD/nectin-1-mediated cell-cell fusion by soluble HSV-1 and HSV-2 gDs, provided solid structural and functional evidence that HSV-1 and HSV-2 recognize nectin-1 via the same binding mode. Finally, we also demonstrated that nectin-1 I80 is an important residue involved in gD interaction.IMPORTANCEDespite intensified studies, a detailed picture of the molecular features in the HSV-2-gD/nectin-1 interaction remains unavailable. Previous work focused on HSV-1 gD, which folds into an IgV-like core with large terminal extensions and utilizes the extension elements to engage nectin-1. Here, we report the crystal structures of HSV-2 gD in both the free and the nectin-1-bound forms. The atomic intermolecule details for HSV-2-gD/nectin-1 interaction are clearly presented. The observed binding mode is identical to that reported for its HSV-1 counterpart. This structural observation was further supported by our comparative functional assays showing that nectin-1 mutations similarly affect the ligand-receptor interaction of both virus gDs. Taken together, we provide comprehensive structural and functional data demonstrating a conserved receptor-binding mode between HSV-1 and HSV-2 for nectin-1. Our results also indicate that the tropism difference between the two viruses likely arises from aspects other than the gD/nectin-1 binding features.