I11-High Resolution Powder Diffraction
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A. J. R.
Thom
,
D. G.
Madden
,
R.
Bueno-Perez
,
A.n.
Al Shakhs
,
C. T.
Lennon
,
R. J.
Marshall
,
C. A.
Walshe
,
C.
Wilson
,
C. A.
Murray
,
S. P.
Thompson
,
G. F.
Turner
,
D.
Bara
,
S. A.
Moggach
,
D.
Fairen-Jimenez
,
R. S.
Forgan
Diamond Proposal Number(s):
[22028]
Open Access
Abstract: To achieve optimal performance in gas storage and delivery applications, metal–organic frameworks (MOFs) must combine high gravimetric and volumetric capacities. One potential route to balancing high pore volume with suitable crystal density is interpenetration, where identical nets sit within the void space of one another. Herein, we report an interpenetrated MIL-53 topology MOF, named GUF-1, where one-dimensional Sc(μ2-OH) chains are connected by 4,4′-(ethyne-1,2-diyl)dibenzoate linkers into a material that is an unusual example of an interpenetrated MOF with a rod-like secondary building unit. A combination of modulated self-assembly and grand canonical Monte Carlo simulations are used to optimise the porosity of GUF-1; H2 adsorption isotherms reveal a moderately high Qst for H2 of 7.6 kJ/mol and a working capacity of 41 g/L in a temperature–pressure swing system, which is comparable to benchmark MOFs. These results show that interpenetration is a potentially viable route to high-performance gas storage materials comprised of relatively simple building blocks.
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Jun 2022
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I13-1-Coherence
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Andreas
Wolf
,
Bernhard
Akstaller
,
Silvia
Cipiccia
,
Silja
Flenner
,
Johannes
Hagemann
,
Veronika
Ludwig
,
Pascal
Meyer
,
Andreas
Schropp
,
Max
Schuster
,
Maria
Seifert
,
Mareike
Weule
,
Thilo
Michel
,
Gisela
Anton
,
Stefan
Funk
Diamond Proposal Number(s):
[18540]
Open Access
Abstract: The advent of hard X-ray free-electron lasers enables nanoscopic X-ray imaging with sub-picosecond temporal resolution. X-ray grating interferometry offers a phase-sensitive full-field imaging technique where the phase retrieval can be carried out from a single exposure alone. Thus, the method is attractive for imaging applications at X-ray free-electron lasers where intrinsic pulse-to-pulse fluctuations pose a major challenge. In this work, the single-exposure phase imaging capabilities of grating interferometry are characterized by an implementation at the I13-1 beamline of Diamond Light Source (Oxfordshire, UK). For comparison purposes, propagation-based phase contrast imaging was also performed at the same instrument. The characterization is carried out in terms of the quantitativeness and the contrast-to-noise ratio of the phase reconstructions as well as via the achievable spatial resolution. By using a statistical image reconstruction scheme, previous limitations of grating interferometry regarding the spatial resolution can be mitigated as well as the experimental applicability of the technique.
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May 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[24092]
Open Access
Abstract: Marine archaeological artefacts contain unexpected compounds due to prolonged exposure to the sea. These can remain dormant and embedded within materials until a change in their surrounding environment, such as exposure to oxygen, prompts a transformation. These changes can pose a problem, as acidic compounds are formed which disintegrate the material, or crystals form which physically break the artefact apart. The extent of these transformations is highly heterogeneous due to its dependence on the ability for oxygen to reach and catalyse these reactions. Additionally, these transformations are heavily dependent on the environment the artefact is exposed to, and the pathways available for ingress, either naturally or through previous degradation. This results in materials with a range of different compounds which are often co-located on the macro, micro and nano-scale. Trying to de-convolute these compounds is challenging, and usually requires a suite of complementary techniques to achieve. Here we report on damaging salts found within marine archaeological bricks and show how it is only possible to qualitatively and quantitatively understand what is present by employing a range of analytical techniques, such as XRD, SEM-EDS and SR-XPD. The marine archaeological bricks studied were found to contain a range of different sulfate-based salts, which had grown crystals in preferred orientations. This provides information which will guide further conservation strategies such as how these bricks are stored, conserved and protected in the future.
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May 2022
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I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[22637]
Open Access
Abstract: MreB, the bacterial ancestor of eukaryotic actin, is responsible for shape in most rod-shaped bacteria. Despite belonging to the actin family, the relevance of nucleotide-driven polymerization dynamics for MreB function is unclear. Here, we provide insights into the effect of nucleotide state on membrane binding of Spiroplasma citri MreB5 (ScMreB5). Filaments of ScMreB5WT and an ATPase-deficient mutant, ScMreB5E134A, assemble independently of the nucleotide state. However, capture of the filament dynamics revealed that efficient filament formation and organization through lateral interactions are affected in ScMreB5E134A. Hence, the catalytic glutamate functions as a switch, (a) by sensing the ATP-bound state for filament assembly and (b) by assisting hydrolysis, thereby potentially triggering disassembly, as observed in other actins. Glu134 mutation and the bound nucleotide exhibit an allosteric effect on membrane binding, as observed from the differential liposome binding. We suggest that the conserved ATP-dependent polymerization and disassembly upon ATP hydrolysis among actins has been repurposed in MreBs for modulating filament organization on the membrane.
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May 2022
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I24-Microfocus Macromolecular Crystallography
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Chih-Jen
Wei
,
Wei
Bu
,
Laura A.
Nguyen
,
Joseph D.
Batchelor
,
Junghyun
Kim
,
Stefania
Pittaluga
,
James R.
Fuller
,
Hanh
Nguyen
,
Te-Hui
Chou
,
Jeffrey I.
Cohen
,
Gary J.
Nabel
Diamond Proposal Number(s):
[22894]
Abstract: Epstein-Barr virus (EBV) is the major cause of infectious mononucleosis and is associated with several human cancers and, more recently, multiple sclerosis. Despite its prevalence and health impact, there are currently no vaccines or treatments. Four viral glycoproteins (gp), gp350 and gH/gL/gp42, mediate entry into the major sites of viral replication, B cells, and epithelial cells. Here, we designed a nanoparticle vaccine displaying these proteins and showed that it elicits potent neutralizing antibodies that protect against infection in vivo. We designed single-chain gH/gL and gH/gL/gp42 proteins that were each fused to bacterial ferritin to form a self-assembling nanoparticle. Structural analysis revealed that single-chain gH/gL and gH/gL/gp42 adopted a similar conformation to the wild-type proteins, and the protein spikes were observed by electron microscopy. Single-chain gH/gL or gH/gL/gp42 nanoparticle vaccines were constructed to ensure product homogeneity needed for clinical development. These vaccines elicited neutralizing antibodies in mice, ferrets, and nonhuman primates that inhibited EBV entry into both B cells and epithelial cells. When mixed with a previously reported gp350 nanoparticle vaccine, gp350D123, no immune competition was observed. To confirm its efficacy in vivo, humanized mice were challenged with EBV after passive transfer of IgG from mice vaccinated with control, gH/gL/gp42+gp350D123, or gH/gL+gp350D123 nanoparticles. Although all control animals were infected, only one mouse in each vaccine group that received immune IgG had detectable transient viremia. Furthermore, no EBV lymphomas were detected in immune animals. This bivalent EBV nanoparticle vaccine represents a promising candidate to prevent EBV infection and EBV-related malignancies in humans.
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May 2022
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I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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Diamond Proposal Number(s):
[27031]
Abstract: The receptor binding domain (RBD) of the spike protein of SARS-CoV-2 binds angiotensin converting enzyme-2 (ACE-2) on the surface of epithelial cells, leading to fusion, and entry of the virus into the cell. This interaction can be blocked by the binding of llama-derived nanobodies (VHHs) to the RBD, leading to virus neutralisation. Structural analysis of VHH-RBD complexes by X-ray crystallography enables VHH epitopes to be precisely mapped, and the effect of variant mutations to be interpreted and predicted. Key to this is a protocol for the reproducible production and crystallization of the VHH-RBD complexes. Based on our experience, we describe a workflow for expressing and purifying the proteins, and the screening conditions for generating diffraction quality crystals of VHH-RBD complexes. Production and crystallization of protein complexes takes approximately twelve days, from construction of vectors to harvesting and freezing crystals for data collection.
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May 2022
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[22479]
Open Access
Abstract: Li-rich metal oxides, such as Li1.2Ni0.13Mn0.54Co0.13O2, can deliver high specific capacities because of the redox of lattice O2− in addition to the cations. Observing oxygen distortions is key to understand the redox process. Electron ptychography is a phase-reconstruction method in 4D scanning transmission electron microscopy, providing atomic-resolution phase images with high signal-to-noise ratio and dose efficiency. Herein, we use electron ptychography to image the oxygen shift in Li1.2Ni0.13Mn0.54Co0.13O2 during the first cycle. The picometer-scale precision measurement shows distinct oxygen shifts in the bulk and surface after charging and compares with various theoretical anionic redox models. The shift after discharging is not seen to recover in the bulk accounting for voltage hysteresis; however, it recovers close to the surface, although with a phase change. We suggest that Li1.2Ni0.13Mn0.54Co0.13O2 proceeds distinct oxygen redox in the bulk and surface. The altered oxygen sublattice after first cycle potentially explains the changed voltage profiles of following cycles.
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May 2022
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I03-Macromolecular Crystallography
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Diamond Proposal Number(s):
[18598]
Open Access
Abstract: Sialic acids terminate many N- and O-glycans and are widely distributed on cell surfaces. There are a diverse range of enzymes which interact with these sugars throughout the tree of life. They can act as receptors for influenza and specific betacoronaviruses in viral binding and their cleavage is important in virion release. Sialic acids are also exploited by both commensal and pathogenic bacteria for nutrient acquisition. A common modification of sialic acid is 9-O-acetylation, which can limit the action of sialidases. Some bacteria, including human endosymbionts, employ esterases to overcome this modification. However, few bacterial sialic acid 9-O-acetylesterases (9-O-SAEs) have been structurally characterized. Here, the crystal structure of a 9-O-SAE from Phocaeicola vulgatus (PvSAE) is reported. The structure of PvSAE was determined to resolutions of 1.44 and 2.06 Å using crystals from two different crystallization conditions. Structural characterization revealed PvSAE to be a dimer with an SGNH fold, named after the conserved sequence motif of this family, and a Ser–His–Asp catalytic triad. These structures also reveal flexibility in the most N-terminal α-helix, which provides a barrier to active-site accessibility. Biochemical assays also show that PvSAE deacetylates both mucin and the acetylated chromophore para-nitrophenyl acetate. This structural and biochemical characterization of PvSAE furthers the understanding of 9-O-SAEs and may aid in the discovery of small molecules targeting this class of enzyme.
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May 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[18638]
Open Access
Abstract: Hydroxyapatite (HA) is a complex material, which is often nanocrystalline when found within a biological setting. This work has directly compared the structural characteristics derived from data collected using a conventional laboratory-based X-ray diffractometer with those collected from a dedicated pair distribution function (PDF) beamline at Diamond Light Source. In particular, the application of PDF analysis methods to carbonated HA is evaluated. 20 synthetic samples were measured using both X-ray diffraction (XRD) and PDFs. Both Rietveld refinement (of laboratory XRD data) and real-space refinement (of PDF data) were used to analyse all samples. The results of Rietveld and real-space refinements were compared to evaluate their application to crystalline and nanocrystalline hydroxyapatite. Significant relationships were observed between real-space refinement parameters and increasing carbonate substitution. Understanding the local order of synthetic hydroxyapatite can benefit several fields, including both biomedical and clinical settings.
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May 2022
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Diamond Proposal Number(s):
[18548]
Open Access
Abstract: Interaction of BRCA2 through ca. 30 amino acid residue motifs, BRC repeats, with RAD51 is a conserved feature of the double-strand DNA break repair by homologous recombination in eukaryotes. In humans the binding of the eight BRC repeats is defined by two sequence motifs, FxxA and LFDE, interacting with distinct sites on RAD51. Little is known of the interaction of BRC repeats in other species, especially in protozoans, where variable number of BRC repeats are found in BRCA2 proteins. Here we have studied in detail the interactions of the two BRC repeats in Leishmania infantum BRCA2 with RAD51. We show LiBRC1 is a high-affinity repeat and determine the crystal structure of its complex with LiRAD51. Using truncation mutagenesis of the LiBRC1 repeat, we demonstrate that high affinity binding is maintained in the absence of an LFDE-like motif and suggest compensatory structural features. These observations point towards a divergent evolution of BRC repeats, where a common FxxA-binding ancestor evolved additional contacts for affinity maturation and fine-tuning.
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May 2022
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