Cryo-Electron Microscopy Structure and Interactions of the Human Cytomegalovirus gHgLgO Trimer with Platelet-Derived Growth Factor Receptor Alpha.
Cryo-Electron Microscopy Structure and Interactions of the Human Cytomegalovirus gHgLgO Trimer with Platelet-Derived Growth Factor Receptor Alpha.
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DOI：
10.1128/mbio.02625-21
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发表时间：
2021-10-26
期刊：
影响因子：
6.4
通讯作者：
Jardetzky TS
中科院分区：
文献类型：
--
作者：
Liu J;Vanarsdall A;Chen DH;Chin A;Johnson D;Jardetzky TS
人巨细胞病毒（HCMV）是一种疱疹病毒，在移植患者和新生儿中产生疾病。HCMV进入细胞依赖于结合细胞受体的gH/gL三聚体（gHgLgO）和五聚体（gHgLUL 128 -131）复合物。在这里，我们研究了由AD 169株gH和gL以及TR株gO蛋白形成的HCMV三聚体的结构和与人血小板衍生生长因子受体α（PDGFRα）的相互作用。三个三聚体表面与三个PDGFRα N-末端结构域广泛接触，导致PDGFRα以类似于人手的结构包裹gO，解释了高亲和力相互作用。gO是最不保守的HCMV蛋白之一，具有8种不同的基因型。我们观察到介导gO-gL相互作用的残基高度保守，但PDGFRα界面中的gO变异性更广泛。我们的三聚体结构与先前确定的由不同亚基基因型组成的结构之间的比较表明，gO变异性通过调整gO-PDGFRα界面来调节。我们在gO内鉴定出两个无序且明显糖基化的环，其可以在不破坏PDGFRα结合的情况下缺失。我们还鉴定了4个与PDGFRα接触的gO残基，突变后可显著降低受体结合。这些残基位于gO与PDGFRα的保守接触位点内，可能是抗三聚体中和抗体和HCMV疫苗的关键靶点。最后，我们观察到远离gL相互作用位点的gO突变影响三聚体表达，表明gO的内在折叠或稳定性可以影响三聚体组装的效率。
Human cytomegalovirus (HCMV) is a herpesvirus that produces disease in transplant patients and newborn children. Entry of HCMV into cells relies on gH/gL trimer (gHgLgO) and pentamer (gHgLUL128–131) complexes that bind cellular receptors. Here, we studied the structure and interactions of the HCMV trimer, formed by AD169 strain gH and gL and TR strain gO proteins, with the human platelet-derived growth factor receptor alpha (PDGFRα). Three trimer surfaces make extensive contacts with three PDGFRα N-terminal domains, causing PDGFRα to wrap around gO in a structure similar to a human hand, explaining the high-affinity interaction. gO is among the least conserved HCMV proteins, with 8 distinct genotypes. We observed high conservation of residues mediating gO-gL interactions but more extensive gO variability in the PDGFRα interface. Comparisons between our trimer structure and a previously determined structure composed of different subunit genotypes indicate that gO variability is accommodated by adjustments in the gO-PDGFRα interface. We identified two loops within gO that were disordered and apparently glycosylated, which could be deleted without disrupting PDGFRα binding. We also identified four gO residues that contact PDGFRα, which when mutated produced markedly reduced receptor binding. These residues fall within conserved contact sites of gO with PDGFRα and may represent key targets for anti-trimer neutralizing antibodies and HCMV vaccines. Finally, we observe that gO mutations distant from the gL interaction site impact trimer expression, suggesting that the intrinsic folding or stability of gO can impact the efficiency of trimer assembly.