The Role of Capsid Maturation on Adenovirus Priming for Sequential Uncoating

Pérez-Berná, Ana J.; Ortega-Esteban, Álvaro; Menéndez-Conejero, Rosa; Winkler, Dennis C.; Menéndez, Margarita; Steven, Alasdair C.; Flint, S. J.; Pablo, Pedro; Martín, Carmen San

doi:10.1074/jbc.m112.389957

Cited by 84 publications

(139 citation statements)

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“…As the fiber is a relatively flexible component of the capsid (42), it is hard to distinguish this as a clear morphological feature due to the inherent force-application of AFM imaging. This is consistent with previous reports on AFM imaging of Ad5, which possesses the longer Ad5 wild-type (WT) fiber, in which no visible fibers were reported (25,33). In the AFM images of Ad35F, a small number of particles did exhibit small surface protrusions that are located on each of the vertices of the icosahedral shell (Fig.…”

Section: Afm Imaging Of Intact Ad35f Virionssupporting

confidence: 92%

“…Figure 3c shows all force indentation curves for each of the three icosahedral axes to illustrate that the mechanical response is strongly influenced by the icosahedral symmetry of the capsid. Notably, the spring constant obtained along the icosahedral 3-fold symmetry axis (0.43 N/m) in our studies is in good agreement with that reported for wild-type Ad5 in an independent study using a similar approach (0.46 N/m) (25).…”

Section: Afm Imaging Of Intact Ad35f Virionssupporting

confidence: 91%

“…Hence, our AFM nanoindentation experiments support the notion that the conformational change in the penton base of HAdV upon integrin binding facilitates uncoating. Together with the recent results of Pérez-Berná et al, this indicates that there are at least two consecutive and distinct mechanical events that lead to uncoating (25). The first step occurs during assembly and maturation as the capsid organization is loosened by the proteolytic maturation.…”

Section: Discussionsupporting

confidence: 64%

“…In the HK97 study, it was shown that covalent cross-linking of capsomeres and reorganization of the capsid quaternary structure are responsible for the increase in mechanical strength of the capsid and in its resistance to material fatigue. Proteolytic maturation has the opposite effect in adenovirus, where the mature capsid is more prone to disassembly than are immature capsids, thereby priming the virion for efficient uncoating upon cell entry (25). Finally, phage 29 and norovirus were shown to have built-in prestress in the capsid that strengthens the particles, thereby increasing their survivability in hostile environments (26,27).…”

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confidence: 99%

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Integrin and Defensin Modulate the Mechanical Properties of Adenovirus

Snijder¹,

Reddy

May

et al. 2013

J Virol

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The propensity for capsid disassembly and uncoating of human adenovirus is modulated by interactions with host cell molecules like integrins and alpha defensins. Here, we use atomic force microscopy (AFM) nanoindentation to elucidate, at the single-particle level, the mechanism by which binding of these host molecules affects virus particle elasticity. Our results demonstrate the direct link between integrin or defensin binding and the mechanical properties of the virus. We show that the structure and geometry of adenovirus result in an anisotropic elastic response that relates to icosahedral symmetry. This elastic response changes upon binding host molecules. Whereas integrin binding softens the vertex regions, binding of a human alpha defensin has exactly the opposite effect. Our results reveal that the ability of these host molecules to influence adenovirus disassembly correlates with a direct effect on the elastic strength of the penton region. Host factors that influence adenovirus infectivity thus modulate the elastic properties of the capsid. Our findings reveal a direct link between virus-host interactions and capsid mechanics. Human adenovirus (HAdV) is one of the largest known nonenveloped double-stranded DNA (dsDNA) viruses. The ϳ36-kb viral genome is encapsidated by a pseudo-Tϭ25 icosahedral capsid that is over 90 nm in diameter with a corresponding mass of ϳ150 MDa (1-3). The main capsid proteins form a closed icosahedral shell that is composed of 240 trimeric hexons, 12 pentamers of the penton base, and 12 fiber trimers. In addition, there are four cement capsid proteins (IIIa, VI, VIII, and IX) and five proteins associated with the genomic core of the virion (V, VII, , IVa2, and terminal protein). During the final step of particle maturation, multiple capsid proteins are posttranslationally processed by a viral protease. Approximately one-third of the more than 50 adenovirus types cause acute infections in humans that are generally self-limiting except in immunocompromised patients. Replication-defective adenoviruses are also used in a significant number of gene therapy and vaccine applications (4).Integrin ␣v␤5 is one of several cell surface receptors for adenovirus that mediates internalization of the virus rather than attachment (5-7). Adenovirus binding to integrin ␣v␤5 promotes clustering of the receptors and activates downstream signaling pathways that facilitate virus endocytosis. Integrin binds to exposed RGD motifs on the virus penton base in a maximum stoichiometry of 4:5 (8, 9). This stoichiometric mismatch between integrin ␣v␤5 and the penton base is the result of a steric hindrance. It is also believed that integrin binding causes a conformation change in the penton base. The spiral untwisting of the penton base protein due to integrin binding could relax the interactions of the individual penton base subunits with the neighboring peripentonal hexons as well as cause the release of the fiber protein at the cell surface, thereby facilitating capsid disassembly at a later stage of cell ...

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Section: Afm Imaging Of Intact Ad35f Virionssupporting

confidence: 92%

Section: Afm Imaging Of Intact Ad35f Virionssupporting

confidence: 91%

Section: Discussionsupporting

confidence: 64%

mentioning

confidence: 99%

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Integrin and Defensin Modulate the Mechanical Properties of Adenovirus

Snijder¹,

Reddy

May

et al. 2013

J Virol

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“…However, the assigned location of protein VI is in disagreement with a cryo-EM-based high-resolution model that assigns the same density to protein IIIa (34). Based on in vitro disassembly studies and the provisional structure model, two hypothetical modes of capsid disassembly and protein VI release have been proposed: starting with penton and fiber release (as a unit or sequentially), followed by release of the peripentonal hexons, thus liberating protein VI (12,37); alternatively, initial fiber and penton release also release protein VI, while capsid disintegration and peripentonal hexon release occur only after translocation to the nuclear pore (11,38).…”

mentioning

confidence: 99%

The Amphipathic Helix of Adenovirus Capsid Protein VI Contributes to Penton Release and Postentry Sorting

Martinez

Schellenberger

Vasishtan

et al. 2015

J Virol

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Nuclear delivery of the adenoviral genome requires that the capsid cross the limiting membrane of the endocytic compartment and traverse the cytosol to reach the nucleus. This endosomal escape is initiated upon internalization and involves a highly coordinated process of partial disassembly of the entering capsid to release the membrane lytic internal capsid protein VI. Using wild-type and protein VI-mutated human adenovirus serotype 5 (HAdV-C5), we show that capsid stability and membrane rupture are major determinants of entry-related sorting of incoming adenovirus virions. Furthermore, by using electron cryomicroscopy, as well as penton-and protein VI-specific antibodies, we show that the amphipathic helix of protein VI contributes to capsid stability by preventing premature disassembly and deployment of pentons and protein VI. Thus, the helix has a dual function in maintaining the metastable state of the capsid by preventing premature disassembly and mediating efficient membrane lysis to evade lysosomal targeting. Based on these findings and structural data from cryo-electron microscopy, we suggest a refined disassembly mechanism upon entry. IMPORTANCEIn this study, we show the intricate connection of adenovirus particle stability and the entry-dependent release of the membrane-lytic capsid protein VI required for endosomal escape. We show that the amphipathic helix of the adenovirus internal protein VI is required to stabilize pentons in the particle while coinciding with penton release upon entry and that release of protein VI mediates membrane lysis, thereby preventing lysosomal sorting. We suggest that this dual functionality of protein VI ensures an optimal disassembly process by balancing the metastable state of the mature adenovirus particle.A denoviruses (AdVs) are nonenveloped, double-stranded DNA viruses that assemble in the nuclei of productively infected cells and are released at the end of the infection cycle into the extracellular milieu. Productive infection of new cells requires that the capsid follow a stepwise disassembly process upon entry that, if perfectly executed, results in highly efficient genome transfer to the nucleus (1, 2).The AdV virion is composed of 13 different polypeptides that form an icosahedral capsid encompassing the genome-containing viral core. The capsid is mainly composed of trimeric hexons building up the facets of the capsid. Pentons and fibers are located at each of the 12 vertices, where they form a pentameric penton base from which the trimeric fiber molecule elongates (3-5). In addition the capsid is stabilized via the cement proteins IIIa, VI, VIII, and IX. The capsid encloses the viral core, with the viral genome organized into chromatin through association with the major core protein VII and proteins V, X, TP, and IVa2 (3-5). Following (or concomitant with) capsid assembly, several of the virion proteins undergo proteolytic processing by the virion-incorporated adenoviral proteinase (AVP) (6). This process of virus maturation is essential to render ne...

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Lessons learned from adenovirus (1970–2019)

Nemerow

Flint

2019

FEBS Letters

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Animal viruses are well recognized for their ability to uncover fundamental cell and molecular processes, and adenovirus certainly provides a prime example. This review illustrates the lessons learned from studying adenovirus over the past five decades. We take a look back at the key studies of adenovirus structure and biophysical properties, which revealed the mechanisms of adenovirus association with antibody, cell receptor, and immune molecules that regulate infection. In addition, we discuss the critical contribution of studies of adenovirus gene expression to elucidation of fundamental reactions in pre‐mRNA processing and its regulation. Other pioneering studies furnished the first examples of protein‐primed initiation of DNA synthesis and viral small RNAs. As a nonenveloped virus, adenoviruses have furnished insights into the modes of virus attachment, entry, and penetration of host cells, and we discuss the diversity of cell receptors that support these processes, as well as membrane penetration. As a result of these extensive studies, adenovirus vectors were among the first to be developed for therapeutic applications. We highlight some of the early (unsuccessful) trials and the lessons learned from them.

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The Role of Capsid Maturation on Adenovirus Priming for Sequential Uncoating

Cited by 84 publications

References 64 publications

Integrin and Defensin Modulate the Mechanical Properties of Adenovirus

Integrin and Defensin Modulate the Mechanical Properties of Adenovirus

The Amphipathic Helix of Adenovirus Capsid Protein VI Contributes to Penton Release and Postentry Sorting

Lessons learned from adenovirus (1970–2019)

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