scholarly journals Assembly and Disassembly of the Capsid-Like External Scaffold of Immature Virions during Vaccinia Virus Morphogenesis

2009 ◽  
Vol 83 (18) ◽  
pp. 9140-9150 ◽  
Author(s):  
Himani Bisht ◽  
Andrea S. Weisberg ◽  
Patricia Szajner ◽  
Bernard Moss
Keyword(s):  
Vaccinia Virus ◽  
Transmembrane Domain ◽  
Lattice Structure ◽  
Close Association ◽  
Spherical Shape ◽  
Building Blocks ◽  
Immunogold Electron Microscopy ◽  
Honeycomb Lattice ◽  
Subsequent Stage ◽  
Crescent Formation

ABSTRACT Infectious poxvirus particles are unusual in that they are brick shaped and lack symmetry. Nevertheless, an external honeycomb lattice comprised of a capsid-like protein dictates the spherical shape and size of immature poxvirus particles. In the case of vaccinia virus, trimers of 63-kDa D13 polypeptides form the building blocks of the lattice. In the present study, we addressed two questions: how D13, which has no transmembrane domain, associates with the immature virion (IV) membrane to form the lattice structure and how this scaffold is removed during the subsequent stage of morphogenesis. Interaction of D13 with the A17 membrane protein was demonstrated by immunoaffinity purification and Western blot analysis. In addition, the results of immunogold electron microscopy indicated a close association of A17 and D13 in crescents, as well as in vesicular structures when crescent formation was prevented. Further studies indicated that binding of A17 to D13 was abrogated by truncation of the N-terminal segment of A17. The N-terminal region of A17 was also required for the formation of crescent and IV structures. Disassembly of the D13 scaffold correlated with the processing of A17 by the I7 protease. When I7 expression was repressed, D13 was retained on aberrant virus particles. Furthermore, the morphogenesis of IVs to mature virions was blocked by mutation of the N-terminal but not the C-terminal cleavage site on A17. Taken together, these data indicate that A17 and D13 interactions regulate the assembly and disassembly of the IV scaffold.

scholarly journals Vaccinia Virus A26 and A27 Proteins Form a Stable Complex Tethered to Mature Virions by Association with the A17 Transmembrane Protein

2008 ◽  
Vol 82 (24) ◽  
pp. 12384-12391 ◽  
Author(s):  
Amanda R. Howard ◽  
Tatiana G. Senkevich ◽  
Bernard Moss
Keyword(s):  
Vaccinia Virus ◽  
Matrix Protein ◽  
Transmembrane Domain ◽  
Noncovalent Complex ◽  
Transmembrane Protein ◽  
Amino Acid Identity ◽  
Noncovalent Interaction ◽  
Terminal Segment ◽  
Stable Complex ◽  
Cowpox Virus

ABSTRACT During vaccinia virus replication, mature virions (MVs) are wrapped with cellular membranes, transported to the periphery, and exported as extracellular virions (EVs) that mediate spread. The A26 protein is unusual in that it is present in MVs but not EVs. This distribution led to a proposal that A26 negatively regulates wrapping. A26 also has roles in the attachment of MVs to the cell surface and incorporation of MVs into proteinaceous A-type inclusions in some orthopoxvirus species. However, A26 lacks a transmembrane domain, and nothing is known regarding how it associates with the MV, regulates incorporation of the MV into inclusions, and possibly prevents EV formation. Here, we provide evidence that A26 forms a disulfide-bonded complex with A27 that is anchored to the MV through a noncovalent interaction with the A17 transmembrane protein. In the absence of A27, A26 was unstable, and only small amounts were detected. The interaction of A26 with A27 depended on a C-terminal segment of A26 with 45% amino acid identity to A27. Deletion of A26 failed to enhance EV formation by vaccinia virus, as had been predicted. Nevertheless, the interaction of A26 and A27 may have functional significance, since each is thought to mediate binding to cells through interaction with laminin and heparan sulfate, respectively. We also found that A26 formed a noncovalent complex with A25, a truncated form of the cowpox virus A-type inclusion matrix protein. The latter association suggests a mechanism for incorporation of virions into A-type inclusions in other orthopoxvirus strains.

scholarly journals Self-standing and flexible covalent organic framework (COF) membranes for molecular separation

2020 ◽  
Vol 6 (41) ◽  
pp. eabb1110
Author(s):  
Jiangtao Liu ◽  
Gang Han ◽  
Dieling Zhao ◽  
Kangjia Lu ◽  
Jie Gao ◽  
...  
Keyword(s):  
Building Blocks ◽  
Shape Selectivity ◽  
Honeycomb Lattice ◽  
Free Standing ◽  
Covalent Bonds ◽  
Separation Science ◽  
Covalent Organic Framework ◽  
Molecular Building Blocks ◽  
Almost All ◽  
Organic Framework

Almost all covalent organic framework (COF) materials conventionally fabricated by solvothermal method at high temperatures and pressures are insoluble and unprocessable powders, which severely hinder their widespread applications. This work develops an effective and facile strategy to construct flexible and free-standing pure COF membranes via the liquid-liquid interface-confined reaction at room temperature and atmospheric pressure. The aperture size and channel chemistry of COF membranes can be rationally designed by bridging various molecular building blocks via strong covalent bonds. Benefiting from the highly-ordered honeycomb lattice, high solvent permeances are successfully obtained and follow the trend of acetonitrile > acetone > methanol > ethanol > isopropanol. Interestingly, the imine-linked COF membrane shows higher nonpolar solvent permeances than b-ketoenamine-linked COF due to their difference in pore polarity. Both kinds of COF membranes exhibit high solvent permeances, precise molecular sieving, excellent shape selectivity, and sufficient flexibility for membrane-based separation science and technology.

scholarly journals Circumventing Tolerance to the Prion Protein (PrP): Vaccination with PrP-Displaying Retrovirus Particles Induces Humoral Immune Responses against the Native Form of Cellular PrP

2005 ◽  
Vol 79 (7) ◽  
pp. 4033-4042 ◽  
Author(s):  
Daphne Nikles ◽  
Patricia Bach ◽  
Klaus Boller ◽  
Christoph A. Merten ◽  
Fabio Montrasio ◽  
...  
Keyword(s):  
Prion Protein ◽  
Transmembrane Domain ◽  
Passive Immunization ◽  
Growth Factor Receptor ◽  
Active Immunization ◽  
Immunoglobulin M ◽  
Immunogold Electron Microscopy ◽  
Igg Antibodies ◽  
Wild Type ◽  
Native Form

ABSTRACT Passive immunization with antibodies directed against the cellular form of the prion protein (PrPC) can protect against prion disease. However, active immunization with recombinant prion protein has so far failed to induce antibodies directed against native PrPC expressed on the cell surface. To develop an antiprion vaccine, a retroviral display system presenting either the full-length mouse PrP (PrP209) or the C-terminal 111 amino acids (PrP111) fused to the transmembrane domain of the platelet-derived growth factor receptor was established. Western blot analysis and immunogold electron microscopy of the retroviral display particles revealed successful incorporation of the fusion proteins into the particle membrane. Interestingly, retroviral particles displaying PrP111 (PrPD111 retroparticles) showed higher incorporation efficiencies than those displaying PrP209. Already 7 days after intravenous injection of PrPD111 retroparticles, PrPC-deficient mice (Prnp o/o) showed high immunoglobulin M (IgM) and IgG titers specifically binding the native PrPC molecule as expressed on the surface of T cells isolated from PrPC-overexpressing transgenic mice. More importantly, heterozygous Prnp +/o mice and also wild-type mice showed PrPC-specific IgM and IgG antibodies upon vaccination with PrPD111 retroparticles, albeit at considerably lower levels. Bacterially expressed recombinant PrP, in contrast, was unable to evoke IgG antibodies recognizing native PrPC in wild-type mice. Thus, our data show that PrP or parts thereof can be functionally displayed on retroviral particles and that immunization with PrP retroparticles may serve as a novel promising strategy for vaccination against transmissible spongiform encephalitis.

scholarly journals Vaccinia Virus F1L Protein Is a Tail-Anchored Protein That Functions at the Mitochondria To Inhibit Apoptosis

2005 ◽  
Vol 79 (2) ◽  
pp. 1084-1098 ◽  
Author(s):  
Tara L. Stewart ◽  
Shawn T. Wasilenko ◽  
Michele Barry
Keyword(s):  
Amino Acid ◽  
Vaccinia Virus ◽  
Transmembrane Domain ◽  
In Vitro Transcription ◽  
Translation System ◽  
Reading Frame ◽  
Protease Digestion ◽  
Necessary And Sufficient ◽  
Virus Survival

ABSTRACT Members of the poxvirus family encode multiple immune evasion proteins, including proteins that regulate apoptosis. We recently identified one such protein, F1L, encoded by vaccinia virus, the prototypic member of the poxvirus family. F1L localizes to the mitochondria and inhibits apoptosis by interfering with the release of cytochrome c, the pivotal commitment step in the apoptotic cascade. Sequence analysis of the F1L open reading frame revealed a C-terminal motif composed of a 12-amino-acid transmembrane domain flanked by positively charged lysines, followed by an 8-amino-acid hydrophilic tail. By generating a series of F1L deletion constructs, we show that the C-terminal domain is necessary and sufficient for localization of F1L to the mitochondria. In addition, mutation of lysines 219 and 222 downstream of the C-terminal transmembrane domain resulted in altered localization of F1L to the endoplasmic reticulum. Using F1L protein generated in an in vitro transcription-translation system, we found that F1L was posttranslationally inserted into mitochondria and tightly associated with mitochondrial membranes as demonstrated by resistance to alkaline extraction. Sensitivity to protease digestion showed that the N terminus of F1L was exposed to the cytoplasm. Utilizing various F1L deletion constructs, we found that F1L localization to the mitochondria was necessary to inhibit apoptosis, since constructs that no longer localized to the mitochondria had reduced antiapoptotic ability. Our studies show that F1L is a new member of the tail-anchored protein family that localizes to mitochondria during virus infection and inhibits apoptosis as a means to enhance virus survival.

scholarly journals Role of the vaccinia virus O3 protein in cell entry can be fulfilled by its Sequence flexible transmembrane domain

Virology ◽  
2013 ◽  
Vol 444 (1-2) ◽  
pp. 148-157 ◽  
Author(s):  
P.S. Satheshkumar ◽  
James Chavre ◽  
Bernard Moss
Keyword(s):  
Vaccinia Virus ◽  
Transmembrane Domain ◽  
Cell Entry ◽  
Its Sequence

scholarly journals External scaffold of spherical immature poxvirus particles is made of protein trimers, forming a honeycomb lattice

2005 ◽  
Vol 170 (6) ◽  
pp. 971-981 ◽  
Author(s):  
Patricia Szajner ◽  
Andrea S. Weisberg ◽  
Jacob Lebowitz ◽  
John Heuser ◽  
Bernard Moss
Keyword(s):  
Electron Microscopy ◽  
Amino Acid ◽  
Vaccinia Virus ◽  
Gel Electrophoresis ◽  
Developmental Stages ◽  
Honeycomb Lattice ◽  
Icosahedral Symmetry ◽  
Structural Requirements ◽  
Virus Particles ◽  
Protein Coat

During morphogenesis, poxviruses undergo a remarkable transition from spherical immature forms to brick-shaped infectious particles lacking helical or icosahedral symmetry. In this study, we show that the transitory honeycomb lattice coating the lipoprotein membrane of immature vaccinia virus particles is formed from trimers of a 62-kD protein encoded by the viral D13L gene. Deep-etch electron microscopy demonstrated that anti-D13 antibodies bound to the external protein coat and that lattice fragments were in affinity-purified D13 preparations. Soluble D13 appeared mostly trimeric by gel electrophoresis and ultracentrifugation, which is consistent with structural requirements for a honeycomb. In the presence or absence of other virion proteins, a mutated D13 with one amino acid substitution formed stacks of membrane-unassociated flat sheets that closely resembled the curved honeycombs of immature virions except for the absence of pentagonal facets. A homologous domain that is present in D13 and capsid proteins of certain other lipid-containing viruses support the idea that the developmental stages of poxviruses reflect their evolution from an icosahedral ancestor.

Specific lipid–protein interactions in a novel honeycomb lattice structure of bacteriorhodopsin

1999 ◽  
Vol 55 (7) ◽  
pp. 1251-1256 ◽  
Author(s):  
Hidenori Sato ◽  
Kazuki Takeda ◽  
Koji Tani ◽  
Tomoya Hino ◽  
Tetsuji Okada ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Lattice Structure ◽  
Hexagonal Lattice ◽  
Crystallographic Analysis ◽  
Purple Membrane ◽  
Honeycomb Lattice ◽  
Vesicular Structure ◽  
Lipid Protein Interactions ◽  
Planar Membranes ◽  
Inside Out

In the purple membrane of Halobacterium salinarium, bacteriorhodopsin trimers are arranged in a hexagonal lattice. When purple membrane sheets are incubated at high temperature with neutral detergent, membrane vesicularization takes place, yielding inside-out vesicles with a diameter of 50 nm. The vesicular structure becomes unstable at low temperature, where successive fusion of the vesicles yields a crystal which is composed of stacked planar membranes. X-ray crystallographic analysis reveals that the bacteriorhodopsin trimers are arranged in a honeycomb lattice in each membrane layer and that neighbouring membranes orient in opposite directions. The native structure of the trimeric unit is preserved in the honeycomb lattice, irrespective of alterations in the in-plane orientation of the trimer. One phospholipid tightly bound to a crevice between monomers in the trimeric unit is suggested to act as a glue in the formation of the trimer.

scholarly journals Vaccinia Virus H2 Protein Is an Essential Component of a Complex Involved in Virus Entry and Cell-Cell Fusion

2005 ◽  
Vol 79 (8) ◽  
pp. 4744-4754 ◽  
Author(s):  
Tatiana G. Senkevich ◽  
Bernard Moss
Keyword(s):  
Vaccinia Virus ◽  
Cell Fusion ◽  
Essential Role ◽  
Transmembrane Domain ◽  
Virus Entry ◽  
Recombinant Vaccinia Virus ◽  
Low Ph ◽  
Microscopic Appearance ◽  
Recombinant Vaccinia ◽  
Virus Morphogenesis

ABSTRACT The vaccinia virus H2R gene (VACWR 100) is conserved in all sequenced members of the poxvirus family and encodes a protein with a predicted transmembrane domain and four invariant cysteines. A recombinant vaccinia virus, in which expression of the H2 protein is stringently regulated, was unable to replicate without inducer. However, under nonpermissive conditions, all stages of virus morphogenesis appeared normal and extracellular virions were detected at the tips of actin tails. Nevertheless, virus did not spread to neighboring cells nor did syncytia form after low-pH treatment. Purified -H2 and +H2 virions from cells infected in the absence or presence of inducer, respectively, were indistinguishable in microscopic appearance and contained the same complement of major proteins, though only +H2 virions were infectious. The -H2 virions bound to cells, but their cores did not penetrate into the cytoplasm. In addition, exogenously added -H2 virions were unable to mediate the formation of syncytia after low-pH treatment. In contrast, virions lacking the A27 (p14) protein, which was previously considered to have an essential role in fusion, penetrated cells and induced extensive syncytia. The properties of H2, however, are very similar to those recently reported for the A28 protein. Moreover, coimmunoprecipitation experiments indicated an interaction between H2 and A28. Therefore, H2 and A28 are the only proteins presently known to be specifically required for vaccinia virus entry and are likely components of a fusion complex.

scholarly journals Closed‐Loop Defect States in 2D Materials with Honeycomb Lattice Structure: Molybdenum Disulfide

2021 ◽  
pp. 2100214
Author(s):  
André Niebur ◽  
Tommy Lorenz ◽  
Jan-Ole Joswig ◽  
Gotthard Seifert ◽  
Sibylle Gemming ◽  
...  
Keyword(s):  
Molybdenum Disulfide ◽  
Closed Loop ◽  
Lattice Structure ◽  
2D Materials ◽  
Honeycomb Lattice ◽  
Defect States

scholarly journals Functionalized Tellurene; a candidate large-gap 2D Topological Insulator

2021 ◽  
Author(s):  
Raghottam M Sattigeri ◽  
Prafulla K Jha
Keyword(s):  
Quantum Wells ◽  
Degrees Of Freedom ◽  
Lattice Structure ◽  
Surface Oxidation ◽  
Group Iv ◽  
Honeycomb Lattice ◽  
Spin Orbit Coupling ◽  
Group Vi ◽  
Hall Effects ◽  
Topological Character

Abstract The discovery of group IV and V elemental Xene’s with topologically non-trivial characters in their honeycomb lattice structure (HLS) has led to extensive efforts in realising analogous behaviour in group VI elemental monolayers. Theoretically; it was concluded that, group VI elemental monolayers cannot exist in HLS. However, some recent experimental evidence suggests that group VI elemental monolayers can be realised in HLS. In this letter, we report HLS of group VI elemental monolayer (such as, Tellurene) can be realised to be dynamically stable when functionzalised with Oxygen. The functionalization leads to, peculiar orbital filtering effects (OFE) and broken spatial inversion symmetry which gives rise to the non-trivial topological character. The exotic quantum behaviour of this system is characterized by, spin-orbit coupling induced large-gap (≈ 0.36 eV) with isolated Dirac cone along the edges indicating potential room temperature spin-transport applications. Further investigations of spin Hall conductivity and the Berry curvatures unravel high conductivity as compared to previously explored Xene’s alongside the potential valley Hall effects. The non-trivial topological character is quantified in terms of the Z2 invaraint as ν = 1 and Chern number C = 1. Also, for practical purposes, we report that, hBN/TeO/hBN quantum-wells can be strain engineered to realize a sizable nontrivial gap (≈ 0.11 eV). We finally conclude that, functionalization of group VI elemental monolayer with Oxygen gives rise to, exotic quantum properties which are robust against surface oxidation and degradations while providing viable electronic degrees of freedom for spintronic applications.

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