Rana Anshul, Yilmaz Gulden, Biswas-Fiss Esther E, Biswas Subhasis
Department of Medical and Molecular Sciences, College of Health Sciences, University of Delaware, Newark, DE 19716, USA.
Ammon Pinizzotto Biopharmaceutical Innovation Center, Newark, DE 19713, USA.
Int J Mol Sci. 2025 May 2;26(9):4333. doi: 10.3390/ijms26094333.
Human papillomaviruses (HPVs) are small double-stranded DNA viruses that infect epithelial cells and cause cervical, anogenital, and oropharyngeal cancers. HPV genome replication relies on the viral E1 and E2 proteins to initiate DNA replication. The first step is the assembly of the E1-E2 complex at the origin of replication. We have examined the role of full-length HPV E1 helicase and its interaction with E2 in pre-initiation complex formation. Electrophoretic mobility shift assays (EMSAs) with purified E1 and E2 proteins revealed that the HPV genome does not have a specific E1 binding site, or such a sequence is not required for pre-initiation complex formation. E1 alone did not show any binding to the origin DNA sequences, while E2 facilitated E1 recruitment to the origin, forming the E1-E2-DNA ternary complex. Formation of such a complex required at least two E2 binding sites. These findings led us to propose a novel mechanism in which E2 dimers serve as the primary recruiters of E1 to form the pre-initiation complex. This study provides new insights into the mechanistic role of E2 in the recruitment of E1 at the origin of HPV DNA replication, enhancing our understanding of HPV biology and potentially informing future therapeutic strategies.
人乳头瘤病毒（HPV）是一种小型双链DNA病毒，可感染上皮细胞并引发宫颈癌、肛门生殖器癌和口咽癌。HPV基因组复制依赖病毒E1和E2蛋白启动DNA复制。第一步是E1-E2复合物在复制起点处组装。我们研究了全长HPV E1解旋酶的作用及其在起始前复合物形成过程中与E2的相互作用。用纯化的E1和E2蛋白进行的电泳迁移率变动分析（EMSA）显示，HPV基因组没有特定的E1结合位点，或者起始前复合物形成不需要这样的序列。单独的E1不显示与起始DNA序列的任何结合，而E2促进E1募集到起始位点，形成E1-E2-DNA三元复合物。这种复合物的形成至少需要两个E2结合位点。这些发现使我们提出了一种新机制，即E2二聚体作为E1的主要募集者形成起始前复合物。本研究为E2在HPV DNA复制起点募集E1的机制作用提供了新见解，增强了我们对HPV生物学的理解，并可能为未来的治疗策略提供依据。
