Department of Microbial Pathogenesis, Yale University, New Haven, CT 06511, USA.
Department of Genetics, Yale University, New Haven, CT 06511, USA.
Viruses. 2022 Apr 13;14(4):804. doi: 10.3390/v14040804.
Intracellular trafficking of human papillomavirus (HPV) during virus entry requires γ-secretase, a cellular protease consisting of a complex of four cellular transmembrane (TM) proteins. γ-secretase typically cleaves substrate proteins but it plays a non-canonical role during HPV entry. γ-secretase binds to the HPV minor capsid protein L2 and facilitates its insertion into the endosomal membrane. After insertion, L2 protrudes into the cytoplasm, which allows HPV to bind other cellular factors required for proper virus trafficking into the retrograde transport pathway. Here, we further characterize the interaction between γ-secretase and HPV L2. We show that γ-secretase is required for cytoplasmic protrusion of L2 and that L2 associates strongly with the PS1 catalytic subunit of γ-secretase and stabilizes the γ-secretase complex. Mutational studies revealed that a putative TM domain in HPV16 L2 cannot be replaced by a foreign TM domain, that infectivity of HPV TM mutants is tightly correlated with γ-secretase binding and stabilization, and that the L2 TM domain is required for protrusion of the L2 protein into the cytoplasm. These results provide new insight into the interaction between γ-secretase and L2 and highlight the importance of the native HPV L2 TM domain for proper virus trafficking during entry.
人乳头瘤病毒 (HPV) 在病毒进入细胞时的细胞内运输需要 γ-分泌酶，γ-分泌酶是一种由四个细胞跨膜 (TM) 蛋白组成的细胞蛋白酶。γ-分泌酶通常切割底物蛋白，但在 HPV 进入过程中发挥非典型作用。γ-分泌酶与 HPV 次要衣壳蛋白 L2 结合，并促进其插入内体膜。插入后，L2 突入细胞质，这允许 HPV 结合进入逆行运输途径所必需的其他细胞因子。在这里，我们进一步研究了 γ-分泌酶与 HPV L2 之间的相互作用。我们表明，γ-分泌酶是 L2 细胞质突出所必需的，并且 L2 与 γ-分泌酶的 PS1 催化亚基强烈结合并稳定 γ-分泌酶复合物。突变研究表明，HPV16 L2 中的一个假定 TM 结构域不能被外来 TM 结构域取代，HPV TM 突变体的感染性与 γ-分泌酶结合和稳定密切相关，并且 L2 TM 结构域是 L2 蛋白突入细胞质所必需的。这些结果为 γ-分泌酶与 L2 之间的相互作用提供了新的见解，并强调了 HPV L2 TM 结构域在进入过程中正确病毒运输的重要性。
