具有早泄分泌表型的突变型乙型肝炎核心蛋白衣壳的结构

StephenW

J Mol Biol. 2018 Dec 7;430(24):4941-4954. doi: 10.1016/j.jmb.2018.10.018. Epub 2018 Oct 27.
Structure of Mutant Hepatitis B Core Protein Capsids with Premature Secretion Phenotype.
Böttcher B1, Nassal M2.
Author information

1
    Department of Biochemistry, Cryo Electron Microscopy, Julius Maximillian's University, Josef-Schneider Straße 2, 97080 Würzburg, Germany. Electronic address: [email protected].
2
    Internal Medicine II/Molecular Biology, University Hospital Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany. Electronic address: [email protected].

Abstract

Hepatitis B virus is a major human pathogen that consists of a viral genome surrounded by an icosahedrally ordered core protein and a polymorphic, lipidic envelope that is densely packed with surface proteins. A point mutation in the core protein in which a phenylalanine at position 97 is exchanged for a smaller leucine leads to premature envelopment of the capsid before the genome maturation is fully completed. We have used electron cryo-microscopy and image processing to investigate how the point mutation affects the structure of the capsid at 2.6- to 2.8 Å-resolution. We found that in the mutant the smaller side chain at position 97 is displaced, increasing the size of an adjacent pocket in the center of the spikes of the capsid. In the mutant, this pocket is filled with an unknown density. Phosphorylation of serine residues in the unresolved C-terminal domain of the mutant leaves the structure of the ordered capsid largely unchanged. However, we were able to resolve several previously unresolved residues downstream of proline 144 that precede the phosphorylation-sites. These residues pack against the neighboring subunits and increase the inter-dimer contact suggesting that the C-termini play an important role in capsid stabilization and provide a much larger interaction interface than previously observed.
KEYWORDS:

Hepatitis B virus; cryo electron microscopy; premature envelopment mutant; structure

StephenW

J Mol Biol。 2018年12月7日; 430（24）：4941-4954。 doi：10.1016 / j.jmb.2018.10.018。 Epub 2018年10月27日。
具有早泄分泌表型的突变型乙型肝炎核心蛋白衣壳的结构。
BöttcherB1，Nassal M2。
作者信息

1
    生物化学系，Cryo电子显微镜，Julius Maximillian大学，Josef-SchneiderStraße2,97080Würzburg，德国。电子地址：[email protected]。
2
    内科II /分子生物学，弗莱堡大学医院，HugstesteterStraße55,79106Freiburg，德国。电子地址：[email protected]。

抽象

乙型肝炎病毒是一种主要的人类病原体，由一个由二十面体有序的核心蛋白包围的病毒基因组和一个密集的表面蛋白质的多态脂质包膜组成。核蛋白中的点突变，其中第97位的苯丙氨酸被交换为较小的亮氨酸，导致在基因组成熟完全完成之前衣壳的过早包封。我们使用电子冷冻显微镜和图像处理来研究点突变如何影响衣壳的结构，分辨率为2.6-2.8。我们发现在突变体中，位置97处的较小侧链被置换，增加了衣壳尖峰中心的相邻口袋的大小。在突变体中，这个口袋充满了未知的密度。在突变体的未解析的C末端结构域中丝氨酸残基的磷酸化使得有序衣壳的结构基本不变。然而，我们能够在磷酸化位点之前解析脯氨酸144下游的几个先前未解析的残基。这些残基对邻近的亚基包装并增加二聚体间接触，表明C-末端在衣壳稳定中起重要作用，并提供比先前观察到的更大的相互作用界面。
关键词：

乙型肝炎病毒;低温电子显微镜;早发包膜突变体;结构体