The Human Cytomegalovirus Protein UL116 Interacts with the Viral Endoplasmic-Reticulum-Resident Glycoprotein UL148 and Promotes the Incorporation of gH/gL Complexes into Virions.
The Human Cytomegalovirus Protein UL116 Interacts with the Viral Endoplasmic-Reticulum-Resident Glycoprotein UL148 and Promotes the Incorporation of gH/gL Complexes into Virions.
复制标题
人类巨细胞病毒蛋白 UL116 与病毒内质网糖蛋白 UL148 相互作用，促进 gH/gL 复合物掺入病毒粒子。
DOI：
10.1128/jvi.02207-20
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发表时间：
2021
影响因子：
5.4
通讯作者：
Kamil,JeremyP
中科院分区：
文献类型：
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作者：
Siddiquey,MohammedNA;Schultz,EricP;Yu,Qin;Amendola,Diego;Vezzani,Giacomo;Yu,Dong;Maione,Domenico;Lanchy,Jean-Marc;Ryckman,BrentJ;Merola,Marcello;Kamil,JeremyP
糖蛋白H(Gh)和L(Gl)的异源二聚体构成了跨疱疹病毒保守的病毒膜融合机制的基本元件。在人巨细胞病毒(HCMV)中，糖蛋白UL116在与G1相似的位置上组装在Gh上，形成异源二聚体，并被整合到病毒粒子中。在这里，我们发现UL116促进Gh/gl复合体的表达，是有效产生感染性无细胞病毒粒子所必需的。UL116缺失突变体显示，从感染的成纤维细胞和上皮细胞产生感染性无细胞病毒粒子的缺陷是10倍。伴随这一缺陷的是两个在病毒侵入中起关键作用的二硫键连接的Gh/gl复合体的表达减少：Gh/gl与糖蛋白O(GO)的异源三聚体以及Gh/gl与UL128、UL130和UL131的五聚体复合体。Kifunensine是一种甘露糖苷酶抑制剂，它干扰末端错误折叠的糖蛋白的内质网相关降解(ERAD)，在UL116缺失感染的细胞中恢复了Gh、gl和Go的水平，表明在没有UL116的情况下，HCMV Gh复合体的成分是不稳定的。此外，我们发现Gh/UL116复合体中含有丰富的病毒粒子，因为从野生型而不是UL116缺失的病毒粒子中检测到了一个主要的Gh物种，而不是与其他糖蛋白共价连接的物种。有趣的是，UL116与UL148共沉淀，UL148是一种病毒ER驻留糖蛋白，可以减弱GO的ERAD，我们观察到在UL148缺失的病毒粒子中UL116的水平升高。总之，我们的发现认为UL116是Gh的伴侣，支持Gh/Gl复合体的组装、成熟和并入病毒粒子。IMPORTANCEHCMV是一种β疱疹病毒，在免疫低下的患者以及免疫未成熟的胎儿和早产儿中会引起危险的机会性感染。病毒进入新宿主细胞的潜力在很大程度上由两个可供选择的病毒糖蛋白H(Gh)/糖蛋白L(Gl)复合体控制，这两个复合体在进入过程中发挥重要作用：Gh/gl/Go和Gh/gl/UL128-131。最近发现的一个病毒粒子Gh复合体，由与UL116结合的Gh组成，为促成HCMV感染性的机制增加了一层新的复杂性。在这里，我们证明UL116促进Gh/gl复合体的表达，并且UL116与病毒的内质网驻留糖蛋白UL148相互作用，UL148是支持Gh/gl/Go表达的因子。总体而言，我们的结果表明UL116是GH的伴侣。这些发现对于理解巨细胞病毒的细胞嗜性以及开发针对该病毒的疫苗具有重要的意义。
Heterodimers of glycoproteins H (gH) and L (gL) comprise a basal element of the viral membrane fusion machinery conserved across herpesviruses. In human cytomegalovirus (HCMV), the glycoprotein UL116 assembles onto gH at a position similar to that occupied by gL, forming a heterodimer that is incorporated into virions. Here, we show that UL116 promotes the expression of gH/gL complexes and is required for the efficient production of infectious cell-free virions.UL116-null mutants show a 10-fold defect in production of infectious cell-free virions from infected fibroblasts and epithelial cells. This defect is accompanied by reduced expression of two disulfide-linked gH/gL complexes that play crucial roles in viral entry: the heterotrimer of gH/gL with glycoprotein O (gO) and the pentameric complex of gH/gL with UL128, UL130, and UL131. Kifunensine, a mannosidase inhibitor that interferes with endoplasmic reticulum (ER)-associated degradation (ERAD) of terminally misfolded glycoproteins, restored levels of gH, gL, and gO inUL116-null-infected cells, indicating that constituents of HCMV gH complexes are unstable in the absence of UL116. Further, we find that gH/UL116 complexes are abundant in virions, since a major gH species not covalently linked to other glycoproteins, which has long been observed in the literature, is detected from wild-type but notUL116-null virions. Interestingly, UL116 coimmunoprecipitates with UL148, a viral ER-resident glycoprotein that attenuates ERAD of gO, and we observe elevated levels of UL116 inUL148-null virions. Collectively, our findings argue that UL116 is a chaperone for gH that supports the assembly, maturation, and incorporation of gH/gL complexes into virions.IMPORTANCEHCMV is a betaherpesvirus that causes dangerous opportunistic infections in immunocompromised patients as well as in the immune-naive fetus and preterm infants. The potential of the virus to enter new host cells is governed in large part by two alternative viral glycoprotein H (gH)/glycoprotein L (gL) complexes that play important roles in entry: gH/gL/gO and gH/gL/UL128-131. A recently identified virion gH complex, comprised of gH bound to UL116, adds a new layer of complexity to the mechanisms that contribute to HCMV infectivity. Here, we show that UL116 promotes the expression of gH/gL complexes and that UL116 interacts with the viral ER-resident glycoprotein UL148, a factor that supports the expression of gH/gL/gO. Overall, our results suggest that UL116 is a chaperone for gH. These findings have important implications for understanding HCMV cell tropism as well as for the development of vaccines against the virus.