Smectic viral capsids and the aneurysm instability

Dharmavaram, Sanjay; Rudnick, Joseph; Lawrence, C. Martin; Bruinsma, Robijn

doi:10.1088/1361-648x/aab99a

Cited by 5 publications

(7 citation statements)

References 26 publications

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“…If tail growth is not due to a form of buckling, then the capsid would have to allow for a form of flow of capsid proteins during tail growth. This would require the capsid proteins to be in a fluid or smectic liquid-crystalline state [25] (one would need to understand how a fluid or liquid crystalline shell can withstand the large osmotic pressure that is known to be present inside ds DNA phage viruses in this explanation).…”

Section: Discussionmentioning

confidence: 99%

Kirigami and the Caspar-Klug construction for viral shells with negative Gauss curvature

et al. 2019

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In this work we extend the Caspar-Klug construction to the archaeal viruses, which in recent years have captured the attention of many researchers for their ability to thrive in extreme environments. We assume that the shells of archaeal viruses are composed of hexamers and pentamers-as it is true for icosahedral viruses-together with heptamers, necessary to introduce negative Gauss curvature. Following the original work of Caspar and Klug, we first construct models capable of reproducing the shape observed in Electron Microscopy images of archaeal viruses. Next, using the technique of Kirigami, we present a systematic way to formulate archaeal virus templates from regular hexagonal lattices. Finally, we utilize the presented techniques to build finite element models of archaeal virus geometries and investigate their shapes as a function of material properties. In particular, using thin-shell elasticity theory, we describe a buckling transition as a function of a modified Föppl von Kármán number γ ⋆ and we show how changes in γ ⋆ may initiate the tail formation in the Acidianus two-tailed archaeal virus. I. INTRODUCTION.

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Section: Discussionmentioning

confidence: 99%

Kirigami and the Caspar-Klug construction for viral shells with negative Gauss curvature

et al. 2019

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“…SMV1 virions can undergo massive architectural rearrangements resulting in the development of one or two tails ( 64 ) that may be used to deliver the genome into the host. It has been hypothesized how unduloids used to model ATSV capsids ( 20 ) can store elastic energy in the structure while forming the bulge inside the virion, being able to withstand pressures up to 10 atmospheres ( 65 ). This transformation gradually yields virions that are 300% longer than the initial tail-less particles ( 18 ).…”

Section: Discussionmentioning

confidence: 99%

“…The biomechanics of SMV1, exhibiting nucleocapsid fluidity and low stiffness, is likely to be linked to its enormous morphological plasticity, which would be inconceivable in the case of stiff and brittle capsids with positionally ordered capsid proteins ( 7 , 67 , 68 ). A theoretical model of the ATV capsid ( 20 , 65 ) predicted the cargo to be an isotropic fluid which is able to double its density during tail growth. Dharmavaram et al ( 20 ) proposed that archaeal lemon-shaped viruses are in a smectic liquid crystalline state that supports their transformation ability.…”

Section: Discussionmentioning

confidence: 99%

“…However, whether such capsids possess biomechanical properties, such as fluidity and softness, akin to those of lipid-based membranes or are more like other protein capsids remains unknown. Interestingly, theoretical investigations ( 20 ) suggested that ATV and ATV-like capsids are anisotropic viscoelastic materials, which would facilitate the experimentally observed architectural virion rearrangements. Understanding the properties of the lemon-shaped virions is of great interest not only from a fundamental point of view but also from a biotechnological perspective and could stimulate the development of next-generation biomaterials for biomedicine and nanotechnology.…”

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confidence: 99%

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Mechanical tomography of an archaeal lemon-shaped virus reveals membrane-like fluidity of the capsid and liquid nucleoprotein cargo

Cantero,

Cvirkaite-Krupovic,

Krupovic

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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Archaeal lemon-shaped viruses have unique helical capsids composed of highly hydrophobic protein strands which can slide past each other resulting in remarkable morphological reorganization. Here, using atomic force microscopy, we explore the biomechanical properties of the lemon-shaped virions of Sulfolobus monocaudavirus 1 (SMV1), a double-stranded DNA virus which infects hyperthermophilic (~80 °C) and acidophilic (pH ~ 2) archaea. Our results reveal that SMV1 virions are extremely soft and withstand repeated extensive deformations, reaching remarkable strains of 80% during multiple cycles of consecutive mechanical assaults, yet showing scarce traces of disruption. SMV1 virions can reversibly collapse wall-to-wall, reducing their volume by ~90%. Beyond revealing the exceptional malleability of the SMV1 protein shell, our data also suggest a fluid-like nucleoprotein cargo which can flow inside the capsid, resisting and accommodating mechanical deformations without further alteration. Our experiments suggest a packing fraction of the virus core to be as low as 11%, with the amount of the accessory proteins almost four times exceeding that of the viral genome. Our findings indicate that SMV1 protein capsid displays biomechanical properties of lipid membranes, which is not found among protein capsids of other viruses. The remarkable malleability and fluidity of the SMV1 virions are likely necessary for the structural transformations during the infection and adaptation to extreme environmental conditions.

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“…These latter studies are part of the wider research effort to study stability and mechanical properties of viruses. In this regard, Dharmavaram et al [14] argue that the capsids of certain Archaea-infecting viruses are in a smectic liquid crystalline state in which they can undergo large shape transformations while remaining stable against rupture by osmotic pressure. Using atomic force microscopy (AFM), the issue of virus stability after desiccation was scrutinised, focusing on the role of the genome and structural ions to keep triatoma virus in shape [15].…”

Section: Special Issue On the Physics Of Viral Capsidsmentioning

confidence: 99%