| 1. |
- Bielecki, Johan, 1982, et al.
(författare)
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Electrospray sample injection for single-particle imaging with x-ray lasers
- 2019
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Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of imaging single proteins constitutes an exciting challenge for x-ray lasers. Despite encouraging results on large particles, imaging small particles has proven to be difficult for two reasons: not quite high enough pulse intensity from currently available x-ray lasers and, as we demonstrate here, contamination of the aerosolized molecules by nonvolatile contaminants in the solution. The amount of contamination on the sample depends on the initial droplet size during aerosolization. Here, we show that, with our electrospray injector, we can decrease the size of aerosol droplets and demonstrate virtually contaminant-free sample delivery of organelles, small virions, and proteins. The results presented here, together with the increased performance of next-generation x-ray lasers, constitute an important stepping stone toward the ultimate goal of protein structure determination from imaging at room temperature and high temporal resolution.
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| 2. |
- Chihara, Akane, et al.
(författare)
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A novel capsid protein network allows the characteristic internal membrane structure of Marseilleviridae giant viruses
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Marseilleviridae is a family of giant viruses, showing a characteristic internal membrane with extrusions underneath the icosahedral vertices. However, such large objects, with a maximum diameter of 250 nm are technically difficult to examine at sub-nanometre resolution by cryo-electron microscopy. Here, we tested the utility of 1 MV high-voltage cryo-EM (cryo-HVEM) for single particle structural analysis (SPA) of giant viruses using tokyovirus, a species of Marseilleviridae, and revealed the capsid structure at 7.7 & Aring; resolution. The capsid enclosing the viral DNA consisted primarily of four layers: (1) major capsid proteins (MCPs) and penton proteins, (2) minor capsid proteins (mCPs), (3) scaffold protein components (ScPCs), and (4) internal membrane. The mCPs showed a novel capsid lattice consisting of eight protein components. ScPCs connecting the icosahedral vertices supported the formation of the membrane extrusions, and possibly act like tape measure proteins reported in other giant viruses. The density on top of the MCP trimer was suggested to include glycoproteins. This is the first attempt at cryo-HVEM SPA. We found the primary limitations to be the lack of automated data acquisition and software support for collection and processing and thus achievable resolution. However, the results pave the way for using cryo-HVEM for structural analysis of larger biological specimens.
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| 3. |
- Daurer, Benedikt J., et al.
(författare)
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Experimental strategies for imaging bioparticles with femtosecond hard X-ray pulses
- 2017
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Ingår i: IUCrJ. - : INT UNION CRYSTALLOGRAPHY. - 2052-2525. ; 4, s. 251-262
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the capabilities of the Coherent X-ray Imaging Instrument at the Linac Coherent Light Source to image small biological samples. The weak signal from small samples puts a significant demand on the experiment. Aerosolized Omono River virus particles of similar to 40 nm in diameter were injected into the submicrometre X-ray focus at a reduced pressure. Diffraction patterns were recorded on two area detectors. The statistical nature of the measurements from many individual particles provided information about the intensity profile of the X-ray beam, phase variations in the wavefront and the size distribution of the injected particles. The results point to a wider than expected size distribution (from similar to 35 to similar to 300 nm in diameter). This is likely to be owing to nonvolatile contaminants from larger droplets during aerosolization and droplet evaporation. The results suggest that the concentration of nonvolatile contaminants and the ratio between the volumes of the initial droplet and the sample particles is critical in such studies. The maximum beam intensity in the focus was found to be 1.9 * 10(12) photons per mu m(2) per pulse. The full-width of the focus at half-maximum was estimated to be 500 nm (assuming 20% beamline transmission), and this width is larger than expected. Under these conditions, the diffraction signal from a sample-sized particle remained above the average background to a resolution of 4.25 nm. The results suggest that reducing the size of the initial droplets during aerosolization is necessary to bring small particles into the scope of detailed structural studies with X-ray lasers.
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| 4. |
- Gorkhover, Tais, et al.
(författare)
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Femtosecond X-ray Fourier holography imaging of free-flying nanoparticles
- 2018
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 12:3, s. 150-153
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafast X-ray imaging on individual fragile specimens such as aerosols 1 , metastable particles 2 , superfluid quantum systems 3 and live biospecimens 4 provides high-resolution information that is inaccessible with conventional imaging techniques. Coherent X-ray diffractive imaging, however, suffers from intrinsic loss of phase, and therefore structure recovery is often complicated and not always uniquely defined 4,5 . Here, we introduce the method of in-flight holography, where we use nanoclusters as reference X-ray scatterers to encode relative phase information into diffraction patterns of a virus. The resulting hologram contains an unambiguous three-dimensional map of a virus and two nanoclusters with the highest lateral resolution so far achieved via single shot X-ray holography. Our approach unlocks the benefits of holography for ultrafast X-ray imaging of nanoscale, non-periodic systems and paves the way to direct observation of complex electron dynamics down to the attosecond timescale.
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| 5. |
- Haldar, Sourav, et al.
(författare)
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Precise Triggering and Chemical Control of Single-Virus Fusion within Endosomes
- 2021
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 95:1
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Tidskriftsartikel (refereegranskat)abstract
- Many enveloped viruses infect cells within endocytic compartments. The pH drop that accompanies endosomal maturation, often in conjunction with proteolysis, triggers viral proteins to insert into the endosomal membrane and drive fusion. Fusion dynamics have been studied by tracking viruses within living cells, which limits the precision with which fusion can be synchronized and controlled, and reconstituting viral fusion to synthetic membranes, which introduces nonphysiological membrane curvature and composition. To overcome these limitations, we report chemically controllable triggering of single-virus fusion within endosomes. We isolated influenza (A/Aichi/68; H3N2) virus:endosome conjugates from cells, immobilized them in a microfluidic flow cell, and rapidly and controllably triggered fusion. Observed lipid-mixing kinetics were surprisingly similar to those of influenza virus fusion with model membranes of opposite curvature: 80% of single-virus events had indistinguishable kinetics. This result suggests that endosomal membrane curvature is not a key permissive feature for viral entry, at least lipid mixing. The assay preserved endosomal membrane asymmetry and protein composition, providing a platform to test how cellular restriction factors and altered endosomal trafficking affect viral membrane fusion.IMPORTANCE Many enveloped viruses infect cells via fusion to endosomes, but controlling this process within living cells has been challenging. We studied the fusion of influenza virus virions to endosomes in a chemically controllable manner. Extracting virus: endosome conjugates from cells and exogenously triggering fusion permits precise study of virus:endosome fusion kinetics. Surprisingly, endosomal curvature does not grossly alter fusion kinetics, although membrane deformability does. This supports a model for influenza virus entry where cells restrict or permit membrane fusion by changing deformability, for instance, using interferon-induced proteins.
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| 6. |
- Konold, Patrick E., et al.
(författare)
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Microsecond time-resolved X-ray scattering by utilizing MHz repetition rate at second-generation XFELs
- 2024
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Ingår i: NATURE METHODS. - : NATURE PORTFOLIO. - 1548-7091 .- 1548-7105.
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Tidskriftsartikel (refereegranskat)abstract
- Detecting microsecond structural perturbations in biomolecules has wide relevance in biology, chemistry and medicine. Here we show how MHz repetition rates at X-ray free-electron lasers can be used to produce microsecond time-series of protein scattering with exceptionally low noise levels of 0.001%. We demonstrate the approach by examining J alpha helix unfolding of a light-oxygen-voltage photosensory domain. This time-resolved acquisition strategy is easy to implement and widely applicable for direct observation of structural dynamics of many biochemical processes. The MHz repetition rates available at second-generation X-ray free-electron lasers enable the collection of microsecond time-resolved X-ray scattering data with exceptionally low noise, providing insights into protein structural dynamics.
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| 7. |
- Konold, Patrick, et al.
(författare)
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Microsecond time-resolved X-ray scattering by utilizing MHz repetition rate at second-generation XFELs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Detecting microsecond structural perturbations in biomolecules has wide relevance inbiology, chemistry, and medicine. Here, we show how MHz repetition rates at X-ray freeelectron lasers (XFELs) can be used to produce microsecond time-series of proteinscattering with exceptionally low noise levels of 0.001%. We demonstrate the approach byderiving new mechanistic insight into Jɑ helix unfolding of a Light-Oxygen-Voltage (LOV)photosensory domain. This time-resolved acquisition strategy is easy to implement andwidely applicable for direct observation of structural dynamics of many biochemicalprocesses.
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| 8. |
- Kurimoto, Eiji, et al.
(författare)
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Crystal structure of human proteasome assembly chaperone PAC4 involved in proteasome formation
- 2017
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Ingår i: Protein Science. - : WILEY. - 0961-8368 .- 1469-896X. ; 26:5, s. 1080-1085
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Tidskriftsartikel (refereegranskat)abstract
- The 26S proteasome is a large protein complex, responsible for degradation of ubiquinated proteins in eukaryotic cells. Eukaryotic proteasome formation is a highly ordered process that is assisted by several assembly chaperones. The assembly of its catalytic 20S core particle depends on at least five proteasome-specific chaperones, i.e., proteasome-assembling chaperons 1-4 (PAC1-4) and proteasome maturation protein (POMP). The orthologues of yeast assembly chaperones have been structurally characterized, whereas most mammalian assembly chaperones are not. In the present study, we determined a crystal structure of human PAC4 at 1.90-angstrom resolution. Our crystallographic data identify a hydrophobic surface that is surrounded by charged residues. The hydrophobic surface is complementary to that of its binding partner, PAC3. The surface also exhibits charge complementarity with the proteasomal 4-5 subunits. This will provide insights into human proteasome-assembling chaperones as potential anticancer drug targets.
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| 9. |
- Kördel, Mikael, et al.
(författare)
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Biological Laboratory X-ray Microscopy
- 2018
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Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 24:S2, s. 346-347
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Lundholm, Ida V., et al.
(författare)
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Considerations for three-dimensional image reconstruction from experimental data in coherent diffractive imaging
- 2018
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Ingår i: IUCrJ. - : International Union of Crystallography. - 2052-2525. ; 5, s. 531-541
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Tidskriftsartikel (refereegranskat)abstract
- Diffraction before destruction using X-ray free-electron lasers (XFELs) has the potential to determine radiation-damage-free structures without the need for crystallization. This article presents the three-dimensional reconstruction of the Melbournevirus from single-particle X-ray diffraction patterns collected at the LINAC Coherent Light Source (LCLS) as well as reconstructions from simulated data exploring the consequences of different kinds of experimental sources of noise. The reconstruction from experimental data suffers from a strong artifact in the center of the particle. This could be reproduced with simulated data by adding experimental background to the diffraction patterns. In those simulations, the relative density of the artifact increases linearly with background strength. This suggests that the artifact originates from the Fourier transform of the relatively flat background, concentrating all power in a central feature of limited extent. We support these findings by significantly reducing the artifact through background removal before the phase-retrieval step. Large amounts of blurring in the diffraction patterns were also found to introduce diffuse artifacts, which could easily be mistaken as biologically relevant features. Other sources of noise such as sample heterogeneity and variation of pulse energy did not significantly degrade the quality of the reconstructions. Larger data volumes, made possible by the recent inauguration of high repetition-rate XFELs, allow for increased signal-to-background ratio and provide a way to minimize these artifacts. The anticipated development of three-dimensional Fourier-volume-assembly algorithms which are background aware is an alternative and complementary solution, which maximizes the use of data.
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| 11. |
- Munke, Anna, et al.
(författare)
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Capsid structure of a marine algal virus of the order Picornavirales
- 2020
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Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 94:9
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Tidskriftsartikel (refereegranskat)abstract
- The order Picornavirales includes viruses that infect different kinds of eukaryotes and that share similar properties. The capsid proteins (CPs) of viruses in the order that infect unicellular organisms, such as algae, presumably possess certain characteristics that have changed little over the course of evolution, and thus these viruses may resemble the Picornavirales ancestor in some respects. Herein, we present the capsid structure of Chaetoceros tenuissimus RNA virus type II (CtenRNAV-II) determined using cryo-electron microscopy at a resolution of 3.1 Å, the first alga virus belonging to the family Marnaviridae of the order Picornavirales. A structural comparison to related invertebrate and vertebrate viruses revealed a unique surface loop of the major CP VP1 that had not been observed previously, and further, revealed that another VP1 loop obscures the so-called canyon, which is a host-receptor binding site for many of the mammalian Picornavirales viruses. VP2 has an N-terminal tail, which has previously been reported as a primordial feature of Picornavirales viruses. The above-mentioned and other critical structural features provide new insights on three long-standing theories about Picornavirales: (i) the canyon hypothesis, (ii) the primordial VP2 domain swap, and (iii) the hypothesis that alga Picornavirales viruses could share characteristics with the Picornavirales ancestor.IMPORTANCE Identifying the acquired structural traits in virus capsids is important for elucidating what functions are essential among viruses that infect different hosts. The Picornavirales viruses infect a broad spectrum of hosts, ranging from unicellular algae to insects and mammals and include many human pathogens. Those viruses that infect unicellular protists, such as algae, are likely to have undergone fewer structural changes during the course of evolution compared to those viruses that infect multicellular eukaryotes and thus still share some characteristics with the Picornavirales ancestor. This article describes the first atomic capsid structure of an alga Marnavirus, CtenRNAV-II. A comparison to capsid structures of the related invertebrate and vertebrate viruses identified a number of structural traits that have been functionally acquired or lost during the course of evolution. These observations provide new insights on past theories on the viability and evolution of Picornavirales viruses.
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| 12. |
- Munke, Anna, et al.
(författare)
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Coherent diffraction of single Rice Dwarf Virus particles using soft X-rays at the Linac Coherent Light Source
- 2018
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Ingår i: Nature Scientific Data.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Single particle imaging using X-ray Free Electron Lasers has recently made major advancements that have facilitated experiments on smaller samples compared to the earliest reported works on giant viruses and cells. Here, the technique was used to image the 70 nm Rice dwarf virus, for which the generated dataset is described here. The virus particles were aerosolized and injected into the X-ray beam of the Linac Coherent Light Source. A total number of 36534 diffraction patterns were recorded, of which approximately 10 % were classified as ‘single hits’ by the RedFlamingo software. With the anticipation to advance method development, the dataset along with usage instructions are deposited in the Coherent X-ray imaging data bank, free to access and analyze.
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| 13. |
- Munke, Anna, et al.
(författare)
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Data Descriptor : Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source
- 2016
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Ingår i: Scientific Data. - : Nature Publishing Group. - 2052-4463. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a wellcharacterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 mu m diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 angstrom ngstrom were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.
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| 14. |
- Munke, Anna, et al.
(författare)
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Primordial Capsid and Spooled ssDNA Genome Structures Unravel Ancestral Events of Eukaryotic Viruses
- 2022
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Ingår i: mBio. - : American Society for Microbiology. - 2161-2129 .- 2150-7511. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Marine algae viruses are important for controlling microorganism communities in the marine ecosystem and played fundamental roles during the early events of viral evolution. Here, we have focused on one major group of marine algae viruses, the single-stranded DNA (ssDNA) viruses from the Bacilladnaviridae family. We present the capsid structure of the bacilladnavirus Chaetoceros tenuissimus DNA virus type II (CtenDNAV-II), determined at 2.4-Å resolution. A structure-based phylogenetic analysis supported the previous theory that bacilladnaviruses have acquired their capsid protein via horizontal gene transfer from a ssRNA virus. The capsid protein contains the widespread virus jelly-roll fold but has additional unique features; a third β-sheet and a long C-terminal tail. Furthermore, a low-resolution reconstruction of the CtenDNAV-II genome revealed a partially spooled structure, an arrangement previously only described for dsRNA and dsDNA viruses. Together, these results exemplify the importance of genetic recombination for the emergence and evolution of ssDNA viruses and provide important insights into the underlying mechanisms that dictate genome organization.IMPORTANCE Single-stranded DNA (ssDNA) viruses are an extremely widespread group of viruses that infect diverse hosts from all three domains of life, consequently having great economic, medical, and ecological importance. In particular, bacilladnaviruses are highly abundant in marine sediments and greatly influence the dynamic appearance and disappearance of certain algae species. Despite the importance of ssDNA viruses and the last couple of years' advancements in cryo-electron microscopy, structural information on the genomes of ssDNA viruses remains limited. This paper describes two important achievements: (i) the first atomic structure of a bacilladnavirus capsid, which revealed that the capsid protein gene presumably was acquired from a ssRNA virus in early evolutionary events; and (ii) the structural organization of a ssDNA genome, which retains a spooled arrangement that previously only been observed for double-stranded viruses.
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| 15. |
- Munke, Anna
(författare)
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Small Particles with Big Impact : Structural Studies of Viruses and Toxicological Studies of Nanodiamonds
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanoparticles (NPs) can be found everywhere and their existence has both beneficial and harmful consequences for the environment and living beings. The investigations on which this thesis is based upon have contributed to an increased understanding of some of these particles and to the development of a method that could be used to study their structure.Three different NPs have been studied by different means. In the first study, I describe how single-particle cryo-electron microscopy was used to determine the atomic structure of an algal virus; Chaetoceros tenuissimus RNA virus type II. This virus is taxonomically classified in the order Picornavirales, which includes viruses that infect a wide range of organisms, including humans, plants and insects. By comparing the algal virus structure to structures of related viruses in the order, we could identify a number of traits that were likely acquired or lost among these viruses during the course of evolution. In the second study, rice dwarf virus was utilised as a test sample to develop a new structural biology method, single-particle coherent diffractive imaging (CDI). The method aims to study macromolecules in a single-particle fashion at room temperature with the help of an X-ray free-electron laser, thus enabling studies of fast dynamics without the need to crystallize or freeze the sample. The study was the first of several within a large international collaboration and the first single-particle CDI experiment reported using femtosecond hard X-ray pulses. Despite several advances by the team, many challenges remain for the method to reach its full potential. In the third study, I describe in vitro and in vivo toxicological studies of detonation nanodiamonds (DNDs). I could demonstrate that some DNDs are toxic and that the toxicity is dependent both on the core and surface of the particles. DNDs are suggested for numerous different biomedical applications that alternately utilise their toxic properties or require biocompatibility. The results presented show that these contrasting properties can be exhibited by similar DNDs and that thorough characterisation and close control of the manufacturing process is essential for biomedical applications.This thesis explores how studies of some of nature’s nanoparticles - viruses - can lead to biological insight, how virus NPs can play a role in developing new technologies that may enable an even deeper understanding and explores issues that need to be considered for NPs to reach their potential in biomedical applications.
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| 16. |
- Okamoto, Kenta, et al.
(författare)
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Acquired Functional Capsid Structures in Metazoan Totivirus-like dsRNA Virus
- 2020
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 28:8, s. 888-
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Tidskriftsartikel (refereegranskat)abstract
- Non-enveloped icosahedral double-stranded RNA (dsRNA) viruses possess multifunctional capsids required for their proliferation. Whereas protozoan/fungal dsRNA viruses have a relatively simple capsid structure, which suffices for the intracellular phase in their life cycle, metazoan dsRNA viruses have acquired additional structural features as an adaptation for extracellular cell-to-cell transmission in multicellular hosts. Here, we present the first atomic model of a metazoan dsRNA totivirus-like virus and the structure reveals three unique structural traits: a C-terminal interlocking arm, surface projecting loops, and an obstruction at the pore on the 5-fold symmetry axis. These traits are keys to understanding the capsid functions of metazoan dsRNA viruses, such as particle stability and formation, cell entry, and endogenous intraparticle transcription of mRNA. On the basis of molecular dynamics simulations of the obstructed pore, we propose a possible mechanism of intraparticle transcription in totivirus-like viruses, which dynamically switches between open and closed states of the pore(s).
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| 17. |
- Okamoto, Kenta, et al.
(författare)
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Cryo-EM structure of a Marseilleviridae virus particle reveals a large internal microassembly
- 2018
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 516, s. 239-245
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Tidskriftsartikel (refereegranskat)abstract
- Nucleocytoplasmic large DNA viruses (NCLDVs) blur the line between viruses and cells. Melbournevirus (MelV, family Marseilleviridae) belongs to a new family of NCLDVs. Here we present an electron cryo-microscopy structure of the MelV particle, with the large triangulation number T = 309 constructed by 3080 pseudo-hexagonal capsomers. The most distinct feature of the particle is a large and dense body (LDB) consistently found inside all particles. Electron cryo-tomography of 147 particles shows that the LDB is preferentially located in proximity to the probable lipid bilayer. The LDB is 30 nm in size and its density matches that of a genome/protein complex. The observed LDB reinforces the structural complexity of MelV, setting it apart from other NCLDVs.
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| 18. |
- Okamoto, Kenta, et al.
(författare)
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Structural variability and complexity of the giant Pithovirus sibericum particle revealed by high-voltage electron cryo-tomography and energy-filtered electron cryo-microscopy
- 2017
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The Pithoviridae giant virus family exhibits the largest viral particle known so far, a prolate spheroid up to 2.5 mu m in length and 0.9 mu m in diameter. These particles show significant variations in size. Little is known about the structure of the intact virion due to technical limitations with conventional electron cryo-microscopy (cryo-EM) when imaging thick specimens. Here we present the intact structure of the giant Pithovirus sibericum particle at near native conditions using high-voltage electron cryo-tomography (cryo-ET) and energy-filtered cryo-EM. We detected a previously undescribed low-density outer layer covering the tegument and a periodical structuring of the fibres in the striated apical cork. Energy-filtered Zernike phase-contrast cryo-EM images show distinct substructures inside the particles, implicating an internal compartmentalisation. The density of the interior volume of Pithovirus particles is three quarters lower than that of the Mimivirus. However, it is remarkably high given that the 600 kbp Pithovirus genome is only half the size of the Mimivirus genome and is packaged in a volume up to 100 times larger. These observations suggest that the interior is densely packed with macromolecules in addition to the genomic nucleic acid.
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| 19. |
- Okamoto, Kenta, et al.
(författare)
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Structure and its transformation of elliptical nege- like virus Tanay virus
- 2023
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Ingår i: Journal of General Virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 104:6
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Tidskriftsartikel (refereegranskat)abstract
- Negeviruses that infect insects are recently identified virus species that are phylogenetically related to several plant viruses. They exhibit a unique virion structure, an elliptical core with a short projection. Negeviruses encode two structural proteins, a glycoprotein that forms a short projection, and an envelope protein that forms an elliptical core. The glycoprotein has been reported only in the negeviruses' genes, and not in phylogenetically related plant viruses' genes. In this report, we first describe the three- dimensional electron cryo- microscopy (cryo- EM) structure of Tanay virus (TANAV), one of the nege- like viruses. TANAV particle demonstrates a periodical envelope structure consisting of three layers surrounding the centred viral RNA. The elliptical core dynamically changes its shape under acidic and even low detergent conditions to form bullet- like or tubular shapes. The further cryo- EM studies on these transformed TANAV particles reveal their overall structural rearrangement. These findings suggest putative geometries of TANAV and its transformation in the life cycle, and the potential importance of the short projection for enabling cell entry to the insect hosts.
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| 20. |
- Okamoto, Kenta, et al.
(författare)
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The infectious particle of insect-borne totivirus-like Omono River virus has raised ridges and lacks fibre complexes
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Omono River virus (OmRV) is a double-stranded RNA virus isolated from Culex mosquitos, and it belongs to a group of unassigned insect viruses that appear to be related to Totiviridae. This paper describes electron cryo-microscopy (cryoEM) structures for the intact OmRV virion to 8.9 angstrom resolution and the structure of the empty virus-like-particle, that lacks RNA, to 8.3 angstrom resolution. The icosahedral capsid contains 120-subunits and resembles another closely related arthropod-borne totivirus-like virus, the infectious myonecrosis virus (IMNV) from shrimps. Both viruses have an elevated plateau around their icosahedral 5-fold axes, surrounded by a deep canyon. Sequence and structural analysis suggests that this plateau region is mainly composed of the extended C-terminal region of the capsid proteins. In contrast to IMNV, the infectious form of OmRV lacks extensive fibre complexes at its 5-fold axes as directly confirmed by a contrast-enhancement technique, using Zernike phase-contrast cryo-EM. Instead, these fibre complexes are replaced by a short "plug" structure at the five-fold axes of OmRV. OmRV and IMNV have acquired an extracellular phase, and the structures at the five-fold axes may be significant in adaptation to cell-to-cell transmission in metazoan hosts.
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| 21. |
- Sobolev, Egor, et al.
(författare)
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Megahertz single-particle imaging at the European XFEL
- 2020
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Ingår i: Communications Physics. - : Springer Science and Business Media LLC. - 2399-3650. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of high repetition-rate X-ray free-electron lasers (XFELs) powered by superconducting accelerator technology enables the measurement of significantly more experimental data per day than was previously possible. The European XFEL is expected to provide 27,000 pulses per second, over two orders of magnitude more than any other XFEL. The increased pulse rate is a key enabling factor for single-particle X-ray diffractive imaging, which relies on averaging the weak diffraction signal from single biological particles. Taking full advantage of this new capability requires that all experimental steps, from sample preparation and delivery to the acquisition of diffraction patterns, are compatible with the increased pulse repetition rate. Here, we show that single-particle imaging can be performed using X-ray pulses at megahertz repetition rates. The results obtained pave the way towards exploiting high repetition-rate X-ray free-electron lasers for single-particle imaging at their full repetition rate.
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| 22. |
- Wang, Han, et al.
(författare)
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A full-length infectious cDNA clone of a dsRNA totivirus-like virus
- 2022
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Ingår i: Virology. - : Elsevier. - 0042-6822 .- 1096-0341. ; 576, s. 127-133
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Tidskriftsartikel (refereegranskat)abstract
- Totivirus-like viruses are a group of non-segmented double-stranded (ds)RNA viruses with two open reading frames, which were recently discovered and provisionally assigned to the Totiviridae family. Unlike yeast and protozoan Totiviridae viruses, these totivirus-like viruses infect a diverse spectrum of metazoan hosts and currently have enormous impacts on fisheries and agriculture. We developed the first infectious full-length cDNA clone of a totivirus-like virus, the Omono River virus (OmRV), and produced infectious particles using an RNA -transcript-based method. Compared with the parent wild-type particles from nature, the infectious-cloning OmRV particles have presented strong cytopathic effects, infectivity and similar morphology. Thus far, the established system is one of the few reported systems for generating a non-segmented dsRNA virus cDNA clone.
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| 23. |
- Wang, Han, et al.
(författare)
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Capsid structure of a fungal dsRNA megabirnavirus reveals its previously unidentified surface architecture
- 2023
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 19:2
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Tidskriftsartikel (refereegranskat)abstract
- Rosellinia necatrix megabirnavirus 1-W779 (RnMBV1) is a non-enveloped icosahedral double-stranded (ds)RNA virus that infects the ascomycete fungus Rosellinia necatrix, a causative agent that induces a lethal plant disease white root rot. Herein, we have first resolved the atomic structure of the RnMBV1 capsid at 3.2 Å resolution using cryo-electron microscopy (cryo-EM) single-particle analysis. Compared with other non-enveloped icosahedral dsRNA viruses, the RnMBV1 capsid protein structure exhibits an extra-long C-terminal arm and a surface protrusion domain. In addition, the previously unrecognized crown proteins are identified in a symmetry-expanded cryo-EM model and are present over the 3-fold axes. These exclusive structural features of the RnMBV1 capsid could have been acquired for playing essential roles in transmission and/or particle assembly of the megabirnaviruses. Our findings, therefore, will reinforce the understanding of how the structural and molecular machineries of the megabirnaviruses influence the virulence of the disease-related ascomycete fungus.Author summaryA fungal plant soil-borne pathogen, Rosellinia necatrix, which can cause devastating disease white root rot in many highly valued fruit trees, is difficult to be controlled with conventional approaches such as fungicide applications. Rosellinia necatrix megabirnavirus 1-W779 (RnMBV1) is a dsRNA virus isolated from the R. necatrix field strain, W779, and this virus can be a viro-control candidate to confer hypovirulence in its host R. necatrix. To make use of RnMBV1 in the white root rot disease control, more molecular and structural investigations will offer us more insights. Here, we have performed cryo-electron microscopy (cryo-EM) single-particle analysis, to obtain the first atomic models of RnMBV1 particles. Based on the atomic structures, we found unique both surface and interior features. In addition, we found a previously unidentified protein on the viral surface. These aforementioned structural features might play important roles in the viral life cycles, and will encourage us to apply this fungal virus as a viro-control approach.
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| 24. |
- Wang, Han, et al.
(författare)
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High-resolution comparative atomic structures of two Giardiavirus prototypes infecting G. duodenalis parasite
- 2024
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 20:4
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Tidskriftsartikel (refereegranskat)abstract
- The Giardia lamblia virus (GLV) is a non-enveloped icosahedral dsRNA and endosymbiont virus that infects the zoonotic protozoan parasite Giardia duodenalis (syn. G. lamblia, G. intestinalis), which is a pathogen of mammals, including humans. Elucidating the transmission mechanism of GLV is crucial for gaining an in-depth understanding of the virulence of the virus in G. duodenalis. GLV belongs to the family Totiviridae, which infects yeast and protozoa intracellularly; however, it also transmits extracellularly, similar to the phylogenetically, distantly related toti-like viruses that infect multicellular hosts. The GLV capsid structure is extensively involved in the longstanding discussion concerning extracellular transmission in Totiviridae and toti-like viruses. Hence, this study constructed the first high-resolution comparative atomic models of two GLV strains, namely GLV-HP and GLV-CAT, which showed different intracellular localization and virulence phenotypes, using cryogenic electron microscopy single-particle analysis. The atomic models of the GLV capsids presented swapped C-terminal extensions, extra surface loops, and a lack of cap-snatching pockets, similar to those of toti-like viruses. However, their open pores and absence of the extra crown protein resemble those of other yeast and protozoan Totiviridae viruses, demonstrating the essential structures for extracellular cell-to-cell transmission. The structural comparison between GLV-HP and GLV-CAT indicates the first evidence of critical structural motifs for the transmission and virulence of GLV in G. duodenalis.
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| 25. |
- Wang, Han
(författare)
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Structural Decorations in Viruses : Unraveling Acquired Functional Structures in Icosahedral RNA Virus Capsids
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Viruses have a profound impact worldwide, posing challenges to animal welfare, agriculture, human health, and the ecosystem. This thesis examines the realm of non-enveloped icosahedral double-stranded (ds)RNA and single-stranded (ss)RNA viruses through three studies. In Paper I, we employed a reverse genetics approach to generate recombinant dsRNA totivirus-like viruses—which negatively impact fisheries and the economy—unraveling the intricate relationships between viral genes and life cycles. Our reverse genetic method has proven essential for generating infectious totivirus-like virus particles, allowing for a nuanced exploration of viral behaviors. Understanding these behaviors has the potential to help in developing effective virus control approaches. In Paper II, we elucidated the previously unknown capsid structure, uncovering the intriguing acquired features of a dsRNA megabirnavirus—Rosellinia necatrix megabirnavirus 1-W779 (RnMBV1)—through cryogenic electron microscopy single-particle analysis. RnMBV1, a fungal virus, has potential applications in controlling white root rot, a plant disease that causes substantial economic losses. Insights into this viral structural information can enhance our ability to leverage this fungal virus for economic and agricultural benefits. In Paper III, we obtained the capsid atomic models of a Marnaviridae ssRNA virus: Chaetoceros socialis forma radians RNA virus 1. Additionally, we generated a structure-based phylogeny using viral protein structures predicted by AlphaFold2; this was done to enhance our understanding of algal virus-host specificity. As harmful algal blooms (HABs) pose global threats to ecology and the economy, Chaetoceros algae have emerged as a contributing factor. Certain Marnaviridae viruses exhibit specific infection patterns in Chaetoceros, thereby influencing the occurrence and mitigation of HABs. Studies on Marnaviridae viruses collectively provide insights into the interactions between algal viruses and their hosts, paving the way for utilizing marine algal viruses to address HAB-related challenges. Together, our functional and structural analyses will contribute to a broader understanding of both dsRNA and ssRNA viruses, their behaviors, and their potential applications in addressing economic, agricultural, ecological, and healthcare issues.
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| 26. |
- Wang, Han, et al.
(författare)
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Structural Insights into Common and Host-Specific Receptor-Binding Mechanisms in Algal Picorna-like Viruses
- 2022
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Ingår i: Viruses. - : MDPI. - 1999-4915. ; 14:11
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Tidskriftsartikel (refereegranskat)abstract
- Marnaviridae viruses are abundant algal viruses that regulate the dynamics of algal blooms in aquatic environments. They employ a narrow host range because they merely lyse their algal host species. This host-specific lysis is thought to correspond to the unique receptor-binding mechanism of the Marnaviridae viruses. Here, we present the atomic structures of the full and empty capsids of Chaetoceros socialis forma radians RNA virus 1 built-in 3.0 Å and 3.1 Å cryo-electron microscopy maps. The empty capsid structure and the structural variability provide insights into its assembly and uncoating intermediates. In conjunction with the previously reported atomic model of the Chaetoceros tenuissimus RNA virus type II capsid, we have identified the common and diverse structural features of the VP1 surface between the Marnaviridae viruses. We have also tested the potential usage of AlphaFold2 for structural prediction of the VP1s and a subsequent structural phylogeny for classifying Marnaviridae viruses by their hosts. These findings will be crucial for inferring the host-specific receptor-binding mechanism in Marnaviridae viruses.
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| 27. |
- Xie, Ling, 1982-, et al.
(författare)
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3D analysis of human islet amyloid polypeptide crystalline structures in Drosophila melanogaster
- 2019
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 14:10
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the Alzheimer's disease associated polypeptide A beta 42 and the human polypeptide hormon islet amyloid polypeptide (hIAPP) and the prohormone precursor (hproIAPP) in neurons of Drosophila melanogaster leads to the formation of protein aggregates in the fat body tissue surrounding the brain. We determined the structure of these membrane-encircled protein aggregates using transmission electron microscopy (TEM) and observed the dissolution of protein aggregates after starvation. Electron tomography (ET) as an extension of transmission electron microscopy revealed that these aggregates were comprised of granular subunits having a diameter of 20 nm aligned into highly ordered structures in all three dimensions. The three dimensional (3D) lattice of hIAPP granules were constructed of two unit cells, a body centered tetragonal (BCT) and a triclinic unit cell. A 5-fold twinned structure was observed consisting of the cyclic twinning of the BCT and triclinic unit cells. The interaction between the two nearest hIAPP granules in both unit cells is not only governed by the van der Waals forces and the dipole-dipole interaction but potentially also by filament-like structures that can connect the nearest neighbors. Hence, our 3D structural analysis provides novel insight into the aggregation process of hIAPP in the fat body tissue of Drosophila melanogaster.
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| 28. |
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| 29. |
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| 30. |
- Zawada, Katarzyna E., et al.
(författare)
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Influenza Hemifusion Phenotype Depends on Membrane Context : Differences in Cell-Cell and Virus-Cell Fusion
- 2018
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Ingår i: Journal of Molecular Biology. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0022-2836 .- 1089-8638. ; 430:5, s. 594-601
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Tidskriftsartikel (refereegranskat)abstract
- Influenza viral entry into the host cell cytoplasm is accomplished by a process of membrane fusion mediated by the viral hemagglutinin protein. Hem agglutinin acts in a pH-triggered fashion, inserting a short fusion peptide into the host membrane followed by refolding of a coiled-coil structure to draw the viral envelope and host membranes together. Mutations to this fusion peptide provide an important window into viral fusion mechanisms and protein-membrane interactions. Here, we show that a well-described fusion peptide mutant, G1S, has a phenotype that depends strongly on the viral membrane context. The G1S mutant is well known to cause a "hemifusion" phenotype based on experiments in transfected cells, where cells expressing G1S hemagglutinin can undergo lipid mixing in a pH triggered fashion similar to virus but will not support fusion pores. We compare fusion by the G1S hemagglutinin mutant expressed either in cells or in influenza virions and show that this hemifusion phenotype occurs in transfected cells but that native virions are able to support full fusion, albeit at a slower rate and 10-100x reduced infectious titer. We explain this with a quantitative model where the G1S mutant, instead of causing an absolute block of fusion, alters the protein stoichiometry required for fusion. This change slightly slows fusion at high hemagglutinin density, as on the viral surface, but at lower hemagglutinin density produces a hemifusion phenotype. The quantitative model thus reproduces the observed virus-cell and cell-cell fusion phenotypes, yielding a unified explanation where membrane context can control the observed viral fusion phenotype. (C) 2018 Elsevier Ltd. All rights reserved.
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