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Current Opinion in Virology Jun 2019The assembly of exact numbers of protein monomers into the distinct architectures of virus capsids has long been of intrigue. Despite the diseases associated with... (Review)
Review
The assembly of exact numbers of protein monomers into the distinct architectures of virus capsids has long been of intrigue. Despite the diseases associated with viruses, there is a paucity of anti-viral therapies; however, mapping virus capsid assembly at the molecular level may lead to the development of more therapeutics. Native mass spectrometry is a powerful, versatile tool with which to monitor biomolecular assembly pathways and identify key intermediates. Recent highlights in this field in terms of MDa mass measurements, identification of capsid intermediates, and the effect of external parameters on assembly are discussed. Examples from ion mobility spectrometry-mass spectrometry, charge detection mass spectrometry, and gas-phase electrophoretic molecular analysis research are presented.
Topics: Capsid Proteins; Mass Spectrometry; Models, Molecular; Virus Assembly; Virus Physiological Phenomena; Viruses
PubMed: 30861488
DOI: 10.1016/j.coviro.2019.02.006 -
Nature Reviews. Microbiology Aug 2015Major advances have occurred in recent years in our understanding of HIV-1 assembly, release and maturation, as work in this field has been propelled forwards by... (Review)
Review
Major advances have occurred in recent years in our understanding of HIV-1 assembly, release and maturation, as work in this field has been propelled forwards by developments in imaging technology, structural biology, and cell and molecular biology. This increase in basic knowledge is being applied to the development of novel inhibitors designed to target various aspects of virus assembly and maturation. This Review highlights recent progress in elucidating the late stages of the HIV-1 replication cycle and the related interplay between virology, cell and molecular biology, and drug discovery.
Topics: Gene Expression Regulation, Viral; HIV-1; Humans; Viral Proteins; Virus Assembly; Virus Release; Virus Replication
PubMed: 26119571
DOI: 10.1038/nrmicro3490 -
Trends in Microbiology Jan 2011Assembly of virus capsids and surface proteins must be regulated to ensure that the resulting complex is an infectious virion. In this review, we examine assembly of... (Review)
Review
Assembly of virus capsids and surface proteins must be regulated to ensure that the resulting complex is an infectious virion. In this review, we examine assembly of virus capsids, focusing on hepatitis B virus and bacteriophage MS2, and formation of glycoproteins in the alphaviruses. These systems are structurally and biochemically well-characterized and are simplest-case paradigms of self-assembly. Published data suggest that capsid and glycoprotein assembly is subject to allosteric regulation, that is regulation at the level of conformational change. The hypothesis that allostery is a common theme in viruses suggests that deregulation of capsid and glycoprotein assembly by small molecule effectors will be an attractive antiviral strategy, as has been demonstrated with hepatitis B virus.
Topics: Allosteric Regulation; Antiviral Agents; Capsid Proteins; Glycoproteins; Virus Assembly; Viruses
PubMed: 21163649
DOI: 10.1016/j.tim.2010.11.003 -
Wiley Interdisciplinary Reviews.... Jul 2020Viruses are highly ordered supramolecular complexes that have evolved to propagate by hijacking the host cell's machinery. Although viruses are very diverse, spreading... (Review)
Review
Viruses are highly ordered supramolecular complexes that have evolved to propagate by hijacking the host cell's machinery. Although viruses are very diverse, spreading through cells of all kingdoms of life, they share common functions and properties. Next to the general interest in virology, fundamental viral mechanisms are of growing importance in other disciplines such as biomedicine and (bio)nanotechnology. However, in order to optimally make use of viruses and virus-like particles, for instance as vehicle for targeted drug delivery or as building blocks in electronics, it is essential to understand their basic chemical and physical properties and characteristics. In this context, the number of studies addressing the mechanisms governing viral properties and processes has recently grown drastically. This review summarizes a specific part of these scientific achievements, particularly addressing physical virology approaches aimed to understand the self-assembly of viruses and the mechanical properties of viral particles. Using a physicochemical perspective, we have focused on fundamental studies providing an overview of the molecular basis governing these key aspects of viral systems. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.
Topics: Biomechanical Phenomena; Genome, Viral; Humans; Virion; Virus Assembly; Viruses
PubMed: 31960585
DOI: 10.1002/wnan.1613 -
Nature Chemical Biology Mar 2020Although viruses are extremely diverse in shape and size, evolution has led to a limited number of viral classes or lineages, which is probably linked to the assembly... (Review)
Review
Although viruses are extremely diverse in shape and size, evolution has led to a limited number of viral classes or lineages, which is probably linked to the assembly constraints of a viable capsid. Viral assembly mechanisms are restricted to two general pathways, (i) co-assembly of capsid proteins and single-stranded nucleic acids and (ii) a sequential mechanism in which scaffolding-mediated capsid precursor assembly is followed by genome packaging. Cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET), which are revolutionizing structural biology, are central to determining the high-resolution structures of many viral assemblies as well as those of assembly intermediates. This wealth of cryo-EM data has also led to the development and redesign of virus-based platforms for biomedical and biotechnological applications. In this Review, we will discuss recent viral assembly analyses by cryo-EM and cryo-ET showing how natural assembly mechanisms are used to encapsulate heterologous cargos including chemicals, enzymes, and/or nucleic acids for a variety of nanotechnological applications.
Topics: Capsid; Capsid Proteins; Cryoelectron Microscopy; Crystallography, X-Ray; Models, Molecular; Nucleic Acid Conformation; Protein Conformation; Virus Assembly
PubMed: 32080621
DOI: 10.1038/s41589-020-0477-1 -
MBio Oct 2019The flavivirus virion consists of an envelope outer layer, formed by envelope (E) and membrane (M) proteins on a lipid bilayer, and an internal core, formed by capsid...
The flavivirus virion consists of an envelope outer layer, formed by envelope (E) and membrane (M) proteins on a lipid bilayer, and an internal core, formed by capsid (C) protein and genomic RNA. The molecular mechanism of flavivirus assembly is not well understood. Here, we show that Zika virus (ZIKV) NS2A protein recruits genomic RNA, the structural protein prM/E complex, and the NS2B/NS3 protease complex to the virion assembly site and orchestrates virus morphogenesis. Coimmunoprecipitation analysis showed that ZIKV NS2A binds to prM, E, NS2B, and NS3 (but not C, NS4B, or NS5) in a viral RNA-independent manner, whereas prM/E complex does not interact with NS2B/NS3 complex. Remarkably, a single-amino-acid mutation (E103A) of NS2A impairs its binding to prM/E and NS2B/NS3 and abolishes virus production, demonstrating the indispensable role of NS2A/prM/E and NS2A/NS2B/NS3 interactions in virion assembly. In addition, RNA-protein pulldown analysis identified a stem-loop RNA from the 3' untranslated region (UTR) of the viral genome as an "RNA recruitment signal" for ZIKV assembly. The 3' UTR RNA binds to a cytoplasmic loop of NS2A protein. Mutations of two positively charged residues (R96A and R102A) from the cytoplasmic loop reduce NS2A binding to viral RNA, leading to a complete loss of virion assembly. Collectively, our results support a virion assembly model in which NS2A recruits viral NS2B/NS3 protease and structural C-prM-E polyprotein to the virion assembly site; once the C-prM-E polyprotein has been processed, NS2A presents viral RNA to the structural proteins for virion assembly. ZIKV is a recently emerged mosquito-borne flavivirus that can cause devastating congenital Zika syndrome in pregnant women and Guillain-Barré syndrome in adults. The molecular mechanism of ZIKV virion assembly is largely unknown. Here, we report that ZIKV NS2A plays a central role in recruiting viral RNA, structural protein prM/E, and viral NS2B/NS3 protease to the virion assembly site and orchestrating virion morphogenesis. One mutation that impairs these interactions does not significantly affect viral RNA replication but selectively abolishes virion assembly, demonstrating the specific role of these interactions in virus morphogenesis. We also show that the 3' UTR of ZIKV RNA may serve as a "recruitment signal" through binding to NS2A to enter the virion assembly site. Following a coordinated cleavage of C-prM-E at the virion assembly site, NS2A may present the viral RNA to C protein for nucleocapsid formation followed by envelopment with prM/E proteins. The results have provided new insights into flavivirus virion assembly.
Topics: Female; Flavivirus; Genome, Viral; Humans; Mutation; Nucleocapsid; Peptide Hydrolases; Pregnancy; RNA, Viral; Serine Endopeptidases; Viral Envelope Proteins; Viral Nonstructural Proteins; Viral Proteins; Virus Assembly; Virus Replication; Zika Virus; Zika Virus Infection
PubMed: 31662457
DOI: 10.1128/mBio.02375-19 -
Annual Review of Biophysics May 2019Viruses, entities composed of nucleic acids, proteins, and in some cases lipids lack the ability to replicate outside their target cells. Their components self-assemble... (Review)
Review
Viruses, entities composed of nucleic acids, proteins, and in some cases lipids lack the ability to replicate outside their target cells. Their components self-assemble at the nanoscale with exquisite precision-a key to their biological success in infection. Recent advances in structure determination and the development of biophysical tools such as single-molecule spectroscopy and noncovalent mass spectrometry allow unprecedented access to the detailed assembly mechanisms of simple virions. Coupling these techniques with mathematical modeling and bioinformatics has uncovered a previously unsuspected role for genomic RNA in regulating formation of viral capsids, revealing multiple, dispersed RNA sequence/structure motifs [packaging signals (PSs)] that bind cognate coat proteins cooperatively. The PS ensemble controls assembly efficiency and accounts for the packaging specificity seen in vivo. The precise modes of action of the PSs vary between viral families, but this common principle applies across many viral families, including major human pathogens. These insights open up the opportunity to block or repurpose PS function in assembly for both novel antiviral therapy and gene/drug/vaccine applications.
Topics: Animals; Antiviral Agents; Evolution, Molecular; Humans; RNA Viruses; RNA, Viral; Virus Assembly
PubMed: 30951648
DOI: 10.1146/annurev-biophys-052118-115611 -
Biochemical Society Transactions Aug 2021Lipid enveloped viruses contain a lipid bilayer coat that protects their genome to help facilitate entry into the new host cell. This lipid bilayer comes from the host... (Review)
Review
Lipid enveloped viruses contain a lipid bilayer coat that protects their genome to help facilitate entry into the new host cell. This lipid bilayer comes from the host cell which they infect. After viral replication, the mature virion hijacks the host cell plasma membrane where it is then released to infect new cells. This process is facilitated by the interaction between phospholipids that make up the plasma membrane and specialized viral matrix proteins. This step in the viral lifecycle may represent a viable therapeutic strategy for small molecules that aim to block enveloped virus spread. In this review, we summarize the current knowledge on the role of plasma membrane lipid-protein interactions on viral assembly and budding.
Topics: Cell Membrane; Host-Pathogen Interactions; Lipids; Proteins; Virus Assembly
PubMed: 34431495
DOI: 10.1042/BST20200854 -
Archives of Biochemistry and Biophysics Mar 2013Most viruses use a hollow protein shell, the capsid, to enclose the viral genome. Virus capsids are large, symmetric oligomers made of many copies of one or a few types... (Review)
Review
Most viruses use a hollow protein shell, the capsid, to enclose the viral genome. Virus capsids are large, symmetric oligomers made of many copies of one or a few types of protein subunits. Self-assembly of a viral capsid is a complex oligomerization process that proceeds along a pathway regulated by ordered interactions between the participating protein subunits, and that involves a series of (usually transient) assembly intermediates. Assembly of many virus capsids requires the assistance of scaffolding proteins or the viral nucleic acid, which interact with the capsid subunits to promote and direct the process. Once assembled, many capsids undergo a maturation reaction that involves covalent modification and/or conformational rearrangements, which may increase the stability of the particle. The final, mature capsid is a relatively robust protein complex able to protect the viral genome from physicochemical aggressions; however, it is also a metastable, dynamic structure poised to undergo controlled conformational transitions required to perform biologically critical functions during virus entry into cells, intracellular trafficking, and viral genome uncoating. This article provides an updated general overview on structural, biophysical and biochemical aspects of the assembly, stability and dynamics of virus capsids.
Topics: Capsid; Protein Conformation; Viral Proteins; Virus Assembly; Viruses
PubMed: 23142681
DOI: 10.1016/j.abb.2012.10.015 -
Journal of Molecular Biology May 2013We generalize the concept of allostery from the traditional non-active-site control of enzymes to virus maturation. Virtually, all animal viruses transition from a... (Review)
Review
We generalize the concept of allostery from the traditional non-active-site control of enzymes to virus maturation. Virtually, all animal viruses transition from a procapsid noninfectious state to a mature infectious state. The procapsid contains an encoded chemical program that is executed following an environmental cue. We developed an exceptionally accessible virus system for the study of the activators of maturation and the downstream consequences that result in particle stability and infectivity. Nudaurelia capensis omega virus (NωV) is a T=4 icosahedral virus that undergoes a dramatic maturation in which the 490-Å spherical procapsid condenses to a 400-Å icosahedral-shaped capsid with associated specific auto-proteolysis and stabilization. Employing X-ray crystallography, time-resolved electron cryo-microscopy and hydrogen/deuterium exchange as well as biochemistry, it was possible to define the mechanisms of allosteric communication among the four quasi-equivalent subunits in the icosahedral asymmetric unit. These gene products undergo proteolysis at different rates, dependent on quaternary structure environment, while particle stability is conferred globally following only a few local subunit transitions. We show that there is a close similarity between the concepts of tensegrity (associated with geodesic domes and mechanical engineering) and allostery (associated with biochemical control mechanisms).
Topics: Allosteric Regulation; Animals; Homeostasis; Moths; Nodaviridae; Virus Assembly
PubMed: 23485419
DOI: 10.1016/j.jmb.2013.02.021