Critical Residues Involved in the Coassembly of L1 and L2 Capsid Proteins of Human Papillomavirus 16
Critical Residues Involved in the Coassembly of L1 and L2 Capsid Proteins of Human Papillomavirus 16
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DOI：
10.1128/jvi.01819-22
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发表时间：
2023-02-23
影响因子：
5.4
通讯作者：
Gu，Ying
中科院分区：
文献类型：
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作者：
Chen，Jie;Wang，Daning;Gu，Ying
人乳头瘤病毒（HPV）是与宫颈癌、疣和其他上皮肿瘤相关的小DNA病毒。结构研究表明，HPV衣壳由360个拷贝的主要衣壳蛋白L1组成，在T=7二十面体晶格中排列为72个五聚体，与亚化学计量量的次要衣壳蛋白L2共同组装。然而，由于缺乏结构信息，参与L1和L2共组装的残基仍然不确定。在这里，我们研究了溶剂可及性表面（SAS）的HPV 16 L1五聚体的晶体结构中的中心腔残基，因为这些内部暴露的残基可能介导与L2的关联。选择L1蛋白中的20个残基进行分析，其中L1五聚体内腔中的4个残基被鉴定为重要残基：F256、R315、Q317和T340。这四个残基的突变降低了293FT细胞中的PsV（假病毒）感染能力，并且R315、Q317和T340的突变基本上干扰了L2共组装成L1衣壳。与野生型（WT）PsV相比，这些突变PsV还具有降低的内化到宿主细胞中的能力。最后，我们鉴定了L2上的一段带负电荷的残基（氨基酸[aa] 337至340 [EEIE]），其突变完全废除了L2组装成L1衣壳，并随后损害HPV 16 PsVs的内吞作用和感染性。这些发现揭示了HPV L1和L2之间难以捉摸的共组装。重要信息已分离出200多种HPV，其中几种高危型与宫颈癌的发生相关。HPV主要衣壳蛋白L1组装成T=7的二十面体病毒外壳，并与次要衣壳蛋白L2结合，后者在HPV生命周期中起关键作用。尽管L2蛋白的重要作用，其结构和与L1的共组装仍然难以捉摸。在这项研究中，我们分析了氨基酸残基在L1和L2之间的拟议接口。这些位点的某些突变减少了组装到衣壳中的L2蛋白的量，这反过来又导致病毒感染性的降低。关于这些残基以及L1和L2的共组装的知识有助于扩大我们对HPV生物学的理解，并有助于通过靶向L2蛋白来开发针对各种HPV类型的对策。
Human papillomaviruses (HPV) are small DNA viruses associated with cervical cancer, warts, and other epithelial tumors. Structural studies have shown that the HPV capsid consists of 360 copies of the major capsid protein, L1, arranged as 72 pentamers in a T=7 icosahedral lattice, coassembling with substoichiometric amounts of the minor capsid protein, L2. However, the residues involved in the coassembly of L1 and L2 remain undefined due to the lack of structure information. Here, we investigated the solvent accessibility surfaces (SASs) of the central cavity residues of the HPV16 L1 pentamer in the crystal structure because those internal exposed residues might mediate the association with L2. Twenty residues in L1 protein were selected to be analyzed, with four residues in the lumen of the L1 pentamer identified as important: F256, R315, Q317, and T340. Mutations to these four residues reduced the PsV (pseudovirus) infection capacity in 293FT cells, and mutations to R315, Q317, and T340 substantially perturb L2 from coassembling into L1 capsid. Compared with wild-type (WT) PsVs, these mutant PsVs also have a reduced ability to become internalized into host cells. Finally, we identified a stretch of negatively charged residues on L2 (amino acids [aa] 337 to 340 [EEIE]), mutations to which completely abrogate L2 assembly into L1 capsid and subsequently impair the endocytosis and infectivity of HPV16 PsVs. These findings shed light on the elusive coassembly between HPV L1 and L2.IMPORTANCEOver 200 types of HPV have been isolated, with several high-risk types correlated with the occurrence of cervical cancer. The HPV major capsid protein, L1, assembles into a T=7 icosahedral viral shell, and associates with the minor capsid protein, L2, which plays a critical role in the HPV life cycle. Despite the important role of the L2 protein, its structure and coassembly with L1 remain elusive. In this study, we analyzed the amino acid residues at the proposed interface between L1 and L2. Certain mutations at these sites decreased the amount of L2 protein assembled into the capsid, which, in turn, led to a decrease in viral infectivity. Knowledge about these residues and the coassembly of L1 and L2 could help to expand our understanding of HPV biology and aid in the development of countermeasures against a wide range of HPV types by targeting the L2 protein.