Thomas Yanique, Androphy Elliot J
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
J Virol. 2018 Jan 17;92(3). doi: 10.1128/JVI.01912-17. Print 2018 Feb 1.
The papillomavirus (PV) E2 protein is a sequence-specific DNA binding protein that recruits cellular factors to its genome in infected epithelial cells. E2 also binds to and loads the viral E1 DNA helicase at the origin of replication. Posttranslational modifications (PTMs) of PV E2 have been identified as potential regulators of E2 functions. We recently reported lysine 111 (K111) as a target of p300 acetylation in bovine PV (BPV). The di-lysines at 111 and 112 are conserved in almost all papillomaviruses. We pursued a mutational approach to query the functional significance of lysine in human PV (HPV) E2. Amino acid substitutions that prevent acetylation, including arginine, were unable to stimulate transcription and E1-mediated DNA replication. The arginine K111 mutant retained E2 transcriptional repression, nuclear localization, DNA and chromatin binding, and association with E2 binding partners involved in PV transcription and replication. While the replication-defective E2-K111R mutant recruited E1 to the viral replication origin, surprisingly, unwinding of the duplex DNA did not occur. In contrast, the K111 glutamine (K111Q) mutant increased origin melting and stimulated replication compared to wild-type E2. These experiments reveal a novel activity of E2 necessary for denaturing the viral origin that likely depends on acetylation of highly conserved lysine 111. HPV is one of the most common sexually transmitted infections in the United States. Over 200 HPVs have been described, and they manifest in a variety of ways; they can be asymptomatic or can result in benign lesions (papillomas) or progress to malignancy. Although 90% of infections are asymptomatic and resolve easily, HPV16 and -18 alone are responsible for 70% of all cervical cancers, which are almost entirely caused by HPV infection. Interestingly, 60 to 90% of other cancers have been linked to HPV. The goal of this research is to further elucidate the mechanisms that regulate and mediate viral replication.
乳头瘤病毒（PV）E2蛋白是一种序列特异性DNA结合蛋白，在受感染的上皮细胞中，它能将细胞因子募集到其基因组中。E2还能在复制起点与病毒E1 DNA解旋酶结合并加载该酶。PV E2的翻译后修饰（PTM）已被确定为E2功能的潜在调节因子。我们最近报道，赖氨酸111（K111）是牛乳头瘤病毒（BPV）中p300乙酰化的靶点。111和112位的双赖氨酸在几乎所有乳头瘤病毒中都是保守的。我们采用突变方法来探究人乳头瘤病毒（HPV）E2中赖氨酸的功能意义。阻止乙酰化的氨基酸替代，包括精氨酸替代，均无法刺激转录和E1介导的DNA复制。精氨酸K111突变体保留了E2转录抑制、核定位、DNA和染色质结合以及与参与PV转录和复制的E2结合伙伴的关联。虽然复制缺陷型E2-K111R突变体将E1募集到病毒复制起点，但令人惊讶的是，双链DNA并未解旋。相比之下，与野生型E2相比，K111谷氨酰胺（K111Q）突变体增加了起点解链并刺激了复制。这些实验揭示了E2的一种新活性，这种活性对于使病毒起点变性是必需的，可能依赖于高度保守的赖氨酸111的乙酰化。HPV是美国最常见的性传播感染之一。已描述的HPV有200多种，它们有多种表现形式；它们可能无症状，也可能导致良性病变（乳头状瘤）或发展为恶性肿瘤。尽管90%的感染无症状且易于消退，但仅HPV16和 -18就导致了70%的宫颈癌，而这些宫颈癌几乎完全由HPV感染引起。有趣的是，60%至90%的其他癌症也与HPV有关。本研究的目标是进一步阐明调节和介导病毒复制的机制。
