分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Zhu, Ling
Ren, Jingshan
Porta, Claudine
Kotecha, Abhay
Siebert, C. Alistair
Fry, Elizabeth E.
Stuart, David I.
Zhu, Ling
Porta, Claudine
Wenham, Hannah
Panjwani, Anusha
Knowles, Nick J.
Tuthill, Tobias J.
Wang, Xiangxi
Rao, Zihe
Ekstrom, Jens-Ola
Lindberg, A. Michael
Rao, Zihe
Stuart, David I.
摘要： Picornaviruses are responsible for a range of human and animal diseases, but how their RNA genome is packaged remains poorly understood. A particularly poorly studied group within this family are those that lack the internal coat protein, VP4. Here we report the atomic structure of one such virus, Ljungan virus, the type member of the genus Parechovirus B, which has been linked to diabetes and myocarditis in humans. The 3.78-angstrom resolution cryo-electron microscopy structure shows remarkable features, including an extended VP1 C terminus, forming a major protuberance on the outer surface of the virus, and a basic motif at the N terminus of VP3, binding to which orders some 12% of the viral genome. This apparently charge-driven RNA attachment suggests that this branch of the picornaviruses uses a different mechanism of genome encapsidation, perhaps explored early in the evolution of picornaviruses.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Wang, Xiangxi
Gao, Qiang
Sun, Yao
Li, Xuemei
Rao, Zihe
Ren, Jingshan
Stuart, David I.
Fry, Elizabeth E.
Gao, Qiang
Yin, Weidong
Hu, Zhongyu
Wang, Junzhi
Rowlands, David J.
Rowlands, David J.
Stuart, David I.
Rao, Zihe
Rao, Zihe
摘要： Hepatitis A virus(HAV) remains enigmatic, despite 1.4 million cases worldwide annually(1). It differs radically from other picornaviruses, existing in an enveloped form(2) and being unusually stable, both genetically and physically(3), but has proved difficult to study. Here we report high-resolution X-ray structures for the mature virus and the empty particle. The structures of the two particles are indistinguishable, apart from some disorder on the inside of the empty particle. The full virus contains the small viral protein VP4, whereas the empty particle harbours only the uncleaved precursor, VP0. The smooth particle surface is devoid of depressions that might correspond to receptor-binding sites. Peptide scanning data extend the previously reported VP3 antigenic site4, while structure-based predictions(5) suggest further epitopes. HAV contains no pocket factor and can withstand remarkably high temperature and low pH, and empty particles are even more robust than full particles. The virus probably uncoats via a novel mechanism, being assembled differently to other picornaviruses. It utilizes a VP2 'domain swap' characteristic of insect picorna-like viruses(6,7), and structure-based phylogenetic analysis places HAV between typical picornaviruses and the insect viruses. The enigmatic properties of HAV may reflect its position as a link between 'modern' picornaviruses and the more 'primitive' precursor insect viruses; for instance, HAV retains the ability to move from cell-to-cell by transcytosis(8,9).
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