Epstein-Barr Virus gH/gL and Kaposi's Sarcoma-Associated Herpesvirus gH/gL Bind to Different Sites on EphA2 To Trigger Fusion
Epstein-Barr Virus gH/gL and Kaposi's Sarcoma-Associated Herpesvirus gH/gL Bind to Different Sites on EphA2 To Trigger Fusion
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DOI：
10.1128/jvi.01454-20
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发表时间：
2020-11-01
影响因子：
5.4
通讯作者：
Longnecker, Richard
中科院分区：
文献类型：
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作者：
Chen, Jia;Schaller, Samantha;Longnecker, Richard
Epstein-Barr病毒（EBV）和卡波西肉瘤相关疱疹病毒（KSHV）都是人类γ疱疹病毒，在多种恶性肿瘤中很重要。Eph家族受体酪氨酸激酶A2（EphA 2）是KSHV和EBV的细胞受体。先前的研究在KSHV gH的N-末端结构域中鉴定了五个保守残基（ELEFN 50 -54），其对于Eph结合和KSHV感染是关键的。然而，对于EphA 2结合重要的EBV gH/gL的特异性结构域没有很好地描述。我们发现KSHV gH（ELEFN 50 -54）基序对于更高的KSHV融合是重要的，并且EBV gH/gL不利用类似的基序进行融合活性。我们先前鉴定了EBV gL N-糖基化突变体（gL-（NL）-L-69/（SV）-V-71）在上皮细胞中是超促流的，但在B细胞中不是。为了确定该糖基化位点是否可以是EphA 2的结合区域，我们比较了EBV gH/gL和EBV gH/gL-（NL）-L-69/（SV）-V-71突变体的EphA 2结合活性。我们发现EBV gH/gL-（NL）-L-69/（SV）-V-71对EphA 2具有更高的结合亲和力，表明EBV gL N-糖基化位点可能负责抑制gH/gL与EphA 2的结合。在该位点处N-糖基化的丧失可以去除减少EBV gH/gL与EphA 2结合的空间位阻。此外，位于EBV gH/gL的大沟中的突变（R（152）A和G（49）C）也具有与EphA 2的降低的结合。总之，我们的数据表明EphA 2在EBV gH/gL上的结合位点至少部分地接近EBV gL糖基化位点，这部分地解释了KSHV对EphA 2结合亲和力的差异。重要性病毒进入靶细胞是病毒感染的第一步。了解整体进入机制，包括特定病毒糖蛋白与细胞受体的结合机制，可以用于小分子抑制剂的设计和疫苗开发。最近，EphA 2被鉴定为KSHV和EBV的重要进入受体。在本研究中，我们研究了EphA 2和EBV gH/gL内介导这两种蛋白质的相互作用从而允许进入上皮细胞的所需结合位点，并发现其与KSHV gH/gL与EphA 2的相互作用相比有所不同。我们的发现可能会发现新的潜在干预策略，可以阻断靶上皮细胞的EB病毒和KSHV感染。
Both Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are human gammaherpesviruses and are important in a variety of malignancies. Eph family receptor tyrosine kinase A2 (EphA2) is a cellular receptor for KSHV and EBV. Previous studies identified five conserved residues (ELEFN50-54) in the N-terminal domain of KSHV gH that are critical for Eph binding and KSHV infection. However, the specific domains of EBV gH/gL important for EphA2 binding are not well described. We found that the KSHV gH (ELEFN50-54) motif is important for higher KSHV fusion and that EBV gH/gL does not utilize a similar motif for fusion activity. We previously identified that an EBV gL N-glycosylation mutant (gL-(NL)-L-69/(SV)-V-71) was hyperfusogenic in epithelial cells but not in B cells. To determine whether this glycosylation site may be the binding region for EphA2, we compared the EphA2 binding activity of EBV gH/gL and the EBV gH/gL-(NL)-L-69/(SV)-V-71 mutant. We found that EBV gH/gL-(NL)-L-69/(SV)-V-71 had higher binding affinity for EphA2, indicating that the EBV gL N-glycosylation site might be responsible for inhibiting the binding of gH/gL to EphA2. Loss of N-glycosylation at this site may remove steric hindrance that reduces EBV gH/gL binding to EphA2. In addition, the mutations located in the large groove of EBV gH/gL (R(152)A and G(49)C) also have decreased binding with EphA2. Taken together, our data indicate that the binding site of EphA2 on EBV gH/gL is at least in part proximal to the EBV gL glycosylation site, which in part accounts for differences in EphA2 binding affinity by KSHV.IMPORTANCE Virus entry into target cells is the first step for virus infection. Understanding the overall entry mechanism, including the binding mechanism of specific virus glycoproteins with cellular receptors, can be useful for the design of small molecule inhibitors and vaccine development. Recently, EphA2 was identified as an important entry receptor for both KSHV and EBV. In the present study, we investigated the required binding sites within EphA2 and EBV gH/gL that mediate the interaction of these two proteins allowing entry into epithelial cells and found that it differed in compared to the interaction of KSHV gH/gL with EphA2. Our discoveries may uncover new potential interventional strategies that block EBV and KSHV infection of target epithelial cells.