循环蛋白对接蛋白在核心蛋白中对HBV复制的调控

StephenW

Regulation of HBV Replication by Cyclin Docking Motifs in Core Protein
Haitao Liu  1 , Ji Xi  1 , Jianming Hu  2
Affiliations
Affiliations

    1
    Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
    2
    Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA [email protected].

    PMID: 33789995 DOI: 10.1128/JVI.00230-21

Abstract

Hepatitis B virus (HBV) capsid or core protein (HBc) consists of an N-terminal domain (NTD) and C-terminal domain (CTD) connected by a short linker peptide. Dynamic phosphorylation and dephosphorylation of HBc regulate its multiple functions in capsid assembly and viral replication. The cellular cyclin-dependent kinase 2 (CDK2) plays a major role in HBc phosphorylation and furthermore, is incorporated into the viral capsid, accounting for most of the "endogenous kinase" activity associated with the capsid. The packaged CDK2 is thought to play a role in phosphorylating HBc to trigger nucleocapsid disassembly (uncoating), an essential step during viral infection. However, little is currently known on how CDK2 is recruited and packaged into the capsid. We have now identified three RXL motifs, in the HBc NTD, known as cyclin docking motifs (CDMs), which mediates the interactions of various CDK substrates/regulators with CDK/cyclin complexes. Mutations of the CDMs in the HBc NTD reduced CTD phosphorylation and diminished CDK2 packaging into the capsid. Also, the CDM mutations showed little effects on capsid assembly and pregenomic RNA (pgRNA) packaging but impaired the integrity of mature nucleocapsids. Furthermore, the CDM mutations blocked covalently closed circular DNA (CCC DNA) formation during infection while having no effect on or enhancing CCC DNA formation via intracellular amplification. These results indicate that the HBc NTD CDMs play a role in CDK2 recruitment and packaging, which, in turn, is important for productive infection.Author SummaryHepatitis B virus (HBV) is an important global human pathogen and persistently infects hundreds of millions of people, who are at high risk of cirrhosis and liver cancer. HBV capsid packages a host cell protein kinase, the cyclin-dependent kinase 2 (CDK2), which is thought to be required to trigger disassembly of the viral nucleocapsid during infection by phosphorylating the capsid protein, a prerequisite for successful infection. We have identified docking sites on the capsid protein for recruiting CDK2, in complex with its cyclin partner, to facilitate capsid protein phosphorylation and CDK2 packaging. Mutations of these docking sites reduced capsid protein phosphorylation, impaired CDK2 packaging into HBV capsids, and blocked HBV infection. These results provide novel insights regarding CDK2 packaging into HBV capsids and the role of CDK2 in HBV infection and should facilitate the development of antiviral drugs that target the HBV capsid protein.

Copyright © 2021 American Society for Microbiology.

StephenW

循环蛋白对接蛋白在核心蛋白中对HBV复制的调控
刘海涛1，吉溪1，胡建明2
隶属关系
隶属关系

    1个
    宾夕法尼亚州立大学医学院微生物与免疫学系，美国宾夕法尼亚州赫尔希。
    2个
    宾夕法尼亚州立大学医学院微生物与免疫学系，美国宾夕法尼亚州好时市[email protected]。

    PMID：33789995 DOI：10.1128 / JVI.00230-21

抽象的

乙型肝炎病毒（HBV）衣壳或核心蛋白（HBc）由通过短接头肽连接的N末端域（NTD）和C末端域（CTD）组成。 HBc的动态磷酸化和去磷酸化调节其在衣壳装配和病毒复制中的多种功能。细胞周期蛋白依赖性激酶2（CDK2）在HBc磷酸化中起主要作用，此外，它被掺入病毒衣壳中，这说明了与衣壳有关的大多数“内源性激酶”活性。认为包装的CDK2在HBc磷酸化以触发核衣壳解体（脱壳）中起作用，这是病毒感染过程中的重要步骤。但是，对于如何招募CDK2并将其包装到衣壳中，目前知之甚少。现在，我们已经在HBc NTD中鉴定了三个RXL主题，称为细胞周期蛋白对接基序（CDM），它们介导了各种CDK底物/调节因子与CDK /细胞周期蛋白复合物的相互作用。 HBc NTD中CDM的突变减少了CTD的磷酸化，并减少了CDK2包装入衣壳的过程。而且，CDM突变对衣壳装配和前基因组RNA（pgRNA）包装几乎没有影响，但损害了成熟核衣壳的完整性。此外，CDM突变在感染过程中阻断了共价闭合的环状DNA（CCC DNA）的形成，而对细胞内扩增对CCC DNA的形成没有影响或没有增强作用。这些结果表明HBc NTD CDM在CDK2募集和包装中发挥了作用，而这反过来又对生产性感染很重要。肝硬化和肝癌的高危人群。 HBV衣壳包装了一种宿主细胞蛋白激酶，即细胞周期蛋白依赖性激酶2（CDK2），被认为是在感染过程中通过使衣壳蛋白磷酸化来触发病毒核衣壳解体的必需蛋白，而衣壳蛋白是成功感染的先决条件。我们已经确定了衣壳蛋白上的对接位点，与它的细胞周期蛋白伴侣一起募集CDK2，以促进衣壳蛋白磷酸化和CDK2包装。这些停靠位点的突变减少了衣壳蛋白的磷酸化，削弱了CDK2包装入HBV衣壳的能力，并阻止了HBV感染。这些结果为将CDK2包装到HBV衣壳中以及CDK2在HBV感染中的作用提供了新颖的见解，并应促进针对HBV衣壳蛋白的抗病毒药物的开发。

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