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14,096 items found (0 items not approved), displaying 81 to 90.[First/Prev] 5, 6, 7, 8, 9, 10, 11, 12 [Next/Last]

Instruments / Technical Area	Publication Details	Published
Krios II-Titan Krios II at Diamond Krios III-Titan Krios III at Diamond Krios IV-Titan Krios IV at Diamond	Structural basis for membrane attack complex inhibition by CD59 Emma C. Couves , Scott Gardner , Tomas B. Voisin , Jasmine K. Bickel , Phillip J. Stansfeld , Edward W. Tate , Doryen Bubeck Nature Communications 14 DOI: 10.1038/s41467-023-36441-z Diamond Proposal Number(s): [25127] Open Access Show Abstract ▼ Abstract: CD59 is an abundant immuno-regulatory receptor that protects human cells from damage during complement activation. Here we show how the receptor binds complement proteins C8 and C9 at the membrane to prevent insertion and polymerization of membrane attack complex (MAC) pores. We present cryo-electron microscopy structures of two inhibited MAC precursors known as C5b8 and C5b9. We discover that in both complexes, CD59 binds the pore-forming β-hairpins of C8 to form an intermolecular β-sheet that prevents membrane perforation. While bound to C8, CD59 deflects the cascading C9 β-hairpins, rerouting their trajectory into the membrane. Preventing insertion of C9 restricts structural transitions of subsequent monomers and indirectly halts MAC polymerization. We combine our structural data with cellular assays and molecular dynamics simulations to explain how the membrane environment impacts the dual roles of CD59 in controlling pore formation of MAC, and as a target of bacterial virulence factors which hijack CD59 to lyse human cells.	Feb 2023
B21-High Throughput SAXS	eIF4A1-dependent mRNAs employ purine-rich 5’UTR sequences to activate localised eIF4A1-unwinding through eIF4A1-multimerisation to facilitate translation Tobias Schmidt , Adrianna Dabrowska , Joseph A. Waldron , Kelly Hodge , Grigorios Koulouras , Mads Gabrielsen , June Munro , David C. Tack , Gemma Harris , Ewan Mcghee , David Scott , Leo m. Carlin , Danny Huang , John Le quesne , Sara Zanivan , Ania Wilczynska , Martin Bushell Nucleic Acids Research 168 DOI: 10.1093/nar/gkad030 Diamond Proposal Number(s): [21657] Open Access Show Abstract ▼ Abstract: Altered eIF4A1 activity promotes translation of highly structured, eIF4A1-dependent oncogene mRNAs at root of oncogenic translational programmes. It remains unclear how these mRNAs recruit and activate eIF4A1 unwinding specifically to facilitate their preferential translation. Here, we show that single-stranded RNA sequence motifs specifically activate eIF4A1 unwinding allowing local RNA structural rearrangement and translation of eIF4A1-dependent mRNAs in cells. Our data demonstrate that eIF4A1-dependent mRNAs contain AG-rich motifs within their 5’UTR which specifically activate eIF4A1 unwinding of local RNA structure to facilitate translation. This mode of eIF4A1 regulation is used by mRNAs encoding components of mTORC-signalling and cell cycle progression, and renders these mRNAs particularly sensitive to eIF4A1-inhibition. Mechanistically, we show that binding of eIF4A1 to AG-rich sequences leads to multimerization of eIF4A1 with eIF4A1 subunits performing distinct enzymatic activities. Our structural data suggest that RNA-binding of multimeric eIF4A1 induces conformational changes in the RNA resulting in an optimal positioning of eIF4A1 proximal to the RNA duplex enabling efficient unwinding. Our data proposes a model in which AG-motifs in the 5’UTR of eIF4A1-dependent mRNAs specifically activate eIF4A1, enabling assembly of the helicase-competent multimeric eIF4A1 complex, and positioning these complexes proximal to stable localised RNA structure allowing ribosomal subunit scanning.	Feb 2023
E01-JEM ARM 200CF	Visualising Co nanoparticle aggregation and encapsulation in Co/TiO2 catalysts and its mitigation through surfactant residues Chengwu Qiu , Yaroslav Odarchenko , Ines Lezcano-Gonzalez , Qingwei Meng , Tom Slater , Shaojun Xu , Andrew Beale Journal Of Catalysis 236 DOI: 10.1016/j.jcat.2023.02.002 Diamond Proposal Number(s): [23984] Open Access Show Abstract ▼ Abstract: Due to the reducible nature of TiO2, the encapsulation of cobalt nanoparticles (CoNPs) by reduced TiO2-x is often reported to decrease their catalytic performance in reactions such as Fisher-Tropsch synthesis (FTS). Here, we show using HAADF-STEM imaging and electron energy loss spectroscopy (EELS) that a residual C12E4 surfactant used to prepare the CoNPs, remains on the surface of a TiO2 rutile support, preventing the formation of Ti3+/Ti2+ oxides and therefore TiO2-x migration. Furthermore, the presence of these surfactant residues prevents the coalescence and aggregation of CoNPs during catalyst preparation, maintaining the dispersion of CoNPs. As such, using C12E4 in the preparation of Co/TiO2 can be considered beneficial for producing a catalyst with a greater number of active Co species.	Feb 2023
I04-1-Macromolecular Crystallography (fixed wavelength)	Concentration‐dependent inhibition of mesophilic PETases on poly(ethylene terephthalate) can be eliminated by enzyme engineering Luisana Avilan , Bruce R. Lichtenstein , Gerhard Koenig , Michael Zahn , Mark D. Allen , Liliana Oliveira , Matilda Clark , Victoria Bemmer , Rosie Graham , Harry P. Austin , Graham Dominick , Christopher W. Johnson , Gregg T. Beckham , John Mcgeehan , Andrew R. Pickford Chemsuschem DOI: 10.1002/cssc.202202277 Diamond Proposal Number(s): [17212] Show Abstract ▼ Abstract: Enzyme-based depolymerization is a viable approach for recycling of poly(ethylene terephthalate) (PET). PETase from Ideonella sakaiensis (IsPETase) is capable of PET hydrolysis under mild conditions but suffers from concentration-dependent inhibition. Here, we report that this inhibition is dependent on incubation time, the solution conditions and PET surface area. Furthermore, this inhibition is evident in other mesophilic PET-degrading enzymes to varying degrees, independent of the level of PET depolymerization activity. The inhibition has no clear structural basis, but moderately thermostable IsPETase variants exhibit reduced inhibition, and the property is completely absent in the highly thermostable HotPETase, previously engineered by directed evolution, which our simulations suggest results from reduced flexibility around the active site. This work highlights a limitation in applying natural mesophilic hydrolases for PET hydrolysis, and reveals an unexpected positive outcome of engineering these enzymes for enhanced thermostability.	Feb 2023
E02-JEM ARM 300CF	nNPipe: a neural network pipeline for automated analysis of morphologically diverse catalyst systems Kevin P. Treder , Chen Huang , Cameron G. Bell , Thomas J. A. Slater , Manfred E. Schuster , Dogan Ozkaya , Judy S. Kim , Angus I. Kirkland Npj Computational Materials 9 DOI: 10.1038/s41524-022-00949-7 Diamond Proposal Number(s): [25427, 23814] Open Access Show Abstract ▼ Abstract: We describe nNPipe for the automated analysis of morphologically diverse catalyst materials. Automated imaging routines and direct-electron detectors have enabled the collection of large data stacks over a wide range of sample positions at high temporal resolution. Simultaneously, traditional image analysis approaches are slow and hence unsuitable for large data stacks and consequently, researchers have progressively turned towards machine learning and deep learning approaches. Previous studies often detail work on morphologically uniform material systems with clearly discernible features, limited workable image sizes and training data that may be biased due to manual labelling. The nNPipe data-processing method consists of two standalone convolutional neural networks that were exclusively trained on multislice image simulations and enables fast analysis of 2048 × 2048 pixel images. Inference performance compared between idealised and real industrial catalytic samples and insights derived from subsequent data analysis are placed into the context of an automated imaging scenario.	Feb 2023
I15-Extreme Conditions I19-Small Molecule Single Crystal Diffraction	Comparative structural evolution under pressure of powder and single crystals of the layered antiferromagnet FePS3 David M. Jarvis , Matthew J. Coak , Hayrullo Hamidov , Charles R. S. Haines , Giulio I. Lampronti , Cheng Liu , Shiyu Deng , Dominik Daisenberger , David R. Allan , Mark R. Warren , Andrew R. Wildes , Siddharth S. Saxena Physical Review B 107 DOI: 10.1103/PhysRevB.107.054106 Diamond Proposal Number(s): [15949, 23524] Show Abstract ▼ Abstract: FePS 3 is a layered magnetic van der Waals compound that undergoes a Mott insulator-metal transition under applied pressure. The transition has an associated change in the crystal symmetry and magnetic structure. Understanding the underlying physics of these transitions requires a detailed understanding of the crystal structure as a function of pressure. Two conflicting models have previously been proposed for the evolution of the structure with pressure. To settle the disagreement, we present a study of the pressure-dependent crystal structures using both single-crystal and powder x-ray diffraction measurements. We show unambiguously that the highest-pressure transition involves a collapse of the interplanar spacing, along with an increase in symmetry from a monoclinic to a trigonal space group, to the exclusion of other models. Our collected results are crucial for understanding high-pressure behavior in these materials and demonstrate a clear and complete methodology for exploring complex two-dimensional material structures under pressure.	Feb 2023
I04-Macromolecular Crystallography	Evolution of protease activation and specificity via alpha-2-macroglobulin-mediated covalent capture Philipp Knyphausen , Mariana Rangel Pereira , Paul Brear , Marko Hyvonen , Lutz Jermutus , Florian Hollfelder Nature Communications 14 DOI: 10.1038/s41467-023-36099-7 Diamond Proposal Number(s): [18548, 25402] Open Access Show Abstract ▼ Abstract: Tailoring of the activity and specificity of proteases is critical for their utility across industrial, medical and research purposes. However, engineering or evolving protease catalysts is challenging and often labour intensive. Here, we describe a generic method to accelerate this process based on yeast display. We introduce the protease selection system A2Mcap that covalently captures protease catalysts by repurposed alpha-2-macroglobulin (A2Ms). To demonstrate the utility of A2Mcap for protease engineering we exemplify the directed activity and specificity evolution of six serine proteases. This resulted in a variant of Staphylococcus aureus serin-protease-like (Spl) protease SplB, an enzyme used for recombinant protein processing, that no longer requires activation by N-terminal signal peptide removal. SCHEMA-based domain shuffling was used to map the specificity determining regions of Spl proteases, leading to a chimeric scaffold that supports specificity switching via subdomain exchange. The ability of A2Mcap to overcome key challenges en route to tailor-made proteases suggests easier access to such reagents in the future.	Feb 2023
I18-Microfocus Spectroscopy	Observational constraints on the process and products of Martian serpentinization Benjamin M. Tutolo , Nicholas J. Tosca Science Advances 9 DOI: 10.1126/sciadv.add8472 Diamond Proposal Number(s): [15947] Open Access Show Abstract ▼ Abstract: The alteration of olivine-rich rocks to serpentine minerals, (hydr)oxides, and aqueous hydrogen through serpentinization is long thought to have influenced the distribution of habitable environments on early Mars and the evolution of the early Martian hydrosphere and atmosphere. Nevertheless, the planetary importance of Martian serpentinization has remained a matter of debate. To constrain the process and products of Martian serpentinization, we studied serpentinized iron-rich olivines from the 1.1-billion-year Duluth Complex. These data indicate that serpentinized iron-rich olivine would have been accompanied by a fivefold increase in hydrogen production relative to serpentinized terrestrial mantle peridotites. In contrast to previous expectations, this style of serpentinization yields hisingerite as the dominant iron serpentine mineral at comparatively low temperature and pH, consistent with meteorite mineralogy and in situ rover data. The widespread occurrence of oxidized iron-bearing phyllosilicates in highly magnetized regions of the Martian crust supports the hypothesis that serpentinization was more pervasive on early Mars than currently estimated.	Feb 2023
I15-1-X-ray Pair Distribution Function (XPDF) I15-Extreme Conditions	Multiple local symmetries result in a common average polar axis in high-strain BiFeO3-based ceramics Ge Wang , Tengfei Hu , Wenxuan Zhu , Zhilun Lu , Annette Kleppe , Maria Diaz Lopez , Antonio Feteira , Derek C. Sinclair , Zhengqian Fu , Houbing Huang , Dawei Wang , Ian M. Reaney Physical Review Letters 130 DOI: 10.1103/PhysRevLett.130.076801 Diamond Proposal Number(s): [21714, 27500] Show Abstract ▼ Abstract: For the first time, the origin of large electrostrain in pseudocubic BiFeO 3 -based ceramics is verified with direct structural evidence backed by appropriate simulations. We employ advanced structural and microstructural characterizations of BiFeO 3 -based ceramics that exhibit large electrostrain ( > 0.4 % ) to reveal the existence of multiple, nanoscale local symmetries, dominantly tetragonal or orthorhombic, which have a common, averaged direction of polarization over larger, meso- or microscale regions. Phase-field simulations confirm the existence of local nanoscale symmetries, thereby providing a new vision for designing high-performance lead-free ceramics for high-strain actuators.	Feb 2023
I10-Beamline for Advanced Dichroism	Observation of the skyrmion side-face state in a chiral magnet Xiaodong Xie , Kejing Ran , Yizhou Liu , Raymond Fan , Wancong Tan , Haonan Jin , Manuel Valvidares , Nicolas Jaouen , Haifeng Du , Gerrit Van Der Laan , Thorsten Hesjedal , Shilei Zhang Physical Review B 107 DOI: 10.1103/PhysRevB.107.L060405 Diamond Proposal Number(s): [20437, 26148, 22629] Show Abstract ▼ Abstract: We identify a three-dimensional skyrmion side-face state in chiral magnets that consists of a thin layer of modulated surface spirals and an array of phase-locked skyrmion screws. Such chiral spin structures lead to a characteristic X-shaped magnetic diffraction pattern in resonant elastic x-ray scattering, reminiscent of Photo 51 of the DNA double-helix diffraction. By measuring both thin plates and bulk Cu 2 OSeO 3 crystals in the field-in-plane geometry, we unambiguously identify the modulated skyrmion strings by retrieving their chirality and helix angle. The breaking of the translational symmetry along the side faces suppresses the bulk-favored conical state, providing a stabilization mechanism for the skyrmion lattice phase that has been overlooked so far.	Feb 2023

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