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Abstract：
The carboxy-terminal tail of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope protein (E) contains a PDZ-binding motif (PBM) which is crucial for coronavirus pathogenicity. During SARS-CoV-2 infection, the viral E protein is expressed within the Golgi apparatus membrane of host cells with its PBM facing the cytoplasm. In this work, we study the molecular mechanisms controlling the presentation of the PBM to host PDZ (PSD-95/Dlg/ZO-1) domain-containing proteins. We show that at the level of the Golgi apparatus, the PDZ-binding motif of the E protein is not detected by E C-terminal specific antibodies nor by the PDZ domain-containing protein-binding partner. Four alanine substitutions upstream of the PBM in the central region of the E protein tail is sufficient to generate immunodetection by anti-E antibodies and trigger robust recruitment of the PDZ domain-containing protein into the Golgi organelle. Overall, this work suggests that the presentation of the PBM to the cytoplasm is under conformational regulation mediated by the central region of the E protein tail and that PBM presentation probably does not occur at the surface of Golgi cisternae but likely at post-Golgi stages of the viral cycle.
摘要：
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）包膜蛋白（E）的羧基末端尾部含有PDZ结合基序（PBM），这对冠状病毒的致病性至关重要。在SARS-CoV-2感染期间,病毒E蛋白在宿主细胞的高尔基体膜内表达,其PBM面向细胞质。在这项工作中，我们研究了控制PBM向含有PDZ（PSD-95/Dlg/ZO-1）结构域的蛋白质呈递的分子机制。我们证明了在高尔基体的水平上，E蛋白的PDZ结合基序未被EC端特异性抗体或含有PDZ结构域的蛋白结合配偶体检测到。在E蛋白尾的中心区域中的PBM上游的四个丙氨酸取代足以通过抗E抗体产生免疫检测,并触发含有PDZ结构域的蛋白质向高尔基体细胞器的稳健募集。总的来说,这项工作表明，PBM向细胞质的呈递是在E蛋白尾中心区域介导的构象调节下，PBM的呈递可能不发生在高尔基体的表面，而是可能发生在高尔基体后阶段的病毒周期。摘要：SARS-CoV（严重急性呼吸系统综合症冠状病毒）；（PDZ（PSD-95/Dlg/ZO-1）；PBM（PDZ结合基序）。
