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27 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I04-Macromolecular Crystallography	Targeting OGG1 arrests cancer cell proliferation by inducing replication stress Torkild Visnes , Carlos Benítez-Buelga , Armando Cázares-Körner , Kumar Sanjiv , Bishoy M. F. Hanna , Oliver Mortusewicz , Varshni Rajagopal , Julian J. Albers , Daniel W Hagey , Tove Bekkhus , Saeed Eshtad , Juan Miguel Baquero , Geoffrey Masuyer , Olov Wallner , Sarah Müller , Therese Pham , Camilla Göktürk , Azita Rasti , Sharda Suman , Raúl Torres-Ruiz , Antonio Sarno , Elisée Wiita , Evert J. Homan , Stella Karsten , Karthick Marimuthu , Maurice Michel , Tobias Koolmeister , Martin Scobie , Olga Loseva , Ingrid Almlöf , Judith Edda Unterlass , Aleksandra Pettke , Johan Boström , Monica Pandey , Helge Gad , Patrick Herr , Ann-Sofie Jemth , Samir El andaloussi , Christina Kalderén , Sandra Rodriguez-Perales , Javier Benítez , Hans E Krokan , Mikael Altun , Pal Stenmark , Ulrika Warpman Berglund , Thomas Helleday Nucleic Acids Research 434 DOI: 10.1093/nar/gkaa1048 Diamond Proposal Number(s): [15806] Open Access Show Abstract ▼ Abstract: Altered oncogene expression in cancer cells causes loss of redox homeostasis resulting in oxidative DNA damage, e.g. 8-oxoguanine (8-oxoG), repaired by base excision repair (BER). PARP1 coordinates BER and relies on the upstream 8-oxoguanine-DNA glycosylase (OGG1) to recognise and excise 8-oxoG. Here we hypothesize that OGG1 may represent an attractive target to exploit reactive oxygen species (ROS) elevation in cancer. Although OGG1 depletion is well tolerated in non-transformed cells, we report here that OGG1 depletion obstructs A3 T-cell lymphoblastic acute leukemia growth in vitro and in vivo, validating OGG1 as a potential anti-cancer target. In line with this hypothesis, we show that OGG1 inhibitors (OGG1i) target a wide range of cancer cells, with a favourable therapeutic index compared to non-transformed cells. Mechanistically, OGG1i and shRNA depletion cause S-phase DNA damage, replication stress and proliferation arrest or cell death, representing a novel mechanistic approach to target cancer. This study adds OGG1 to the list of BER factors, e.g. PARP1, as potential targets for cancer treatment.	Nov 2020
I04-Macromolecular Crystallography	Structural and biochemical characterization of botulinum neurotoxin subtype B2 binding to its receptors Jonathan R. Davies , Geoffrey Masuyer , Pal Stenmark Toxins 12 DOI: 10.3390/toxins12090603 Diamond Proposal Number(s): [15806] Open Access Show Abstract ▼ Abstract: Botulinum neurotoxins (BoNTs) can be used therapeutically to treat a wide range of neuromuscular and neurological conditions. A collection of natural BoNT variants exists which can be classified into serologically distinct serotypes (BoNT/B), and further divided into subtypes (BoNT/B1, B2, …). BoNT subtypes share a high degree of sequence identity within the same serotype yet can display large variation in toxicity. One such example is BoNT/B2, which was isolated from Clostridium botulinum strain 111 in a clinical case of botulism, and presents a 10-fold lower toxicity than BoNT/B1. In an effort to understand the molecular mechanisms behind this difference in potency, we here present the crystal structures of BoNT/B2 in complex with the ganglioside receptor GD1a, and with the human synaptotagmin I protein receptor. We show, using receptor-binding assays, that BoNT/B2 has a slightly higher affinity for GD1a than BoNT/B1, and confirm its considerably weaker affinity for its protein receptors. Although the overall receptor-binding mechanism is conserved for both receptors, structural analysis suggests the lower affinity of BoNT/B2 is the result of key substitutions, where hydrophobic interactions important for synaptotagmin-binding are replaced by polar residues. This study provides a template to drive the development of future BoNT therapeutic molecules centered on assessing the natural subtype variations in receptor-binding that appears to be one of the principal stages driving toxicity.	Sep 2020
I03-Macromolecular Crystallography	Crystal structure of Exotoxin A from Aeromonas pathogenic species Geoffrey Masuyer Toxins 12 DOI: 10.3390/toxins12060397 Diamond Proposal Number(s): [21625] Open Access Show Abstract ▼ Abstract: Aeromonas exotoxin A (AE) is a bacterial virulence factor recently discovered in a clinical case of necrotising fasciitis caused by the flesh-eating Aeromonas hydrophila. Here, database mining shows that AE is present in the genome of several emerging Aeromonas pathogenic species. The X-ray crystal structure of AE was solved at 2.3 Å and presents all the hallmarks common to diphthamide-specific mono-ADP-ribosylating toxins, suggesting AE is a fourth member of this family alongside the diphtheria toxin, Pseudomonas exotoxin A and cholix. Structural homology indicates AE may use a similar mechanism of cytotoxicity that targets eukaryotic elongation factor 2 and thus inhibition of protein synthesis. The structure of AE also highlights unique features including a metal binding site, and a negatively charged cleft that could play a role in interdomain interactions and may affect toxicity. This study raises new opportunities to engineer alternative toxin-based molecules with pharmaceutical potential.	Jun 2020
I04-Macromolecular Crystallography	Characterization of a membrane binding loop leads to engineering botulinum neurotoxin B with improved therapeutic efficacy Linxiang Yin , Geoffrey Masuyer , Sicai Zhang , Jie Zhang , Shin-Ichiro Miyashita , David Burgin , Laura Lovelock , Shu-Fen Coker , Tian-Min Fu , Pal Stenmark , Min Dong Plos Biology 18 DOI: 10.1371/journal.pbio.3000618 Diamond Proposal Number(s): [15806] Open Access Show Abstract ▼ Abstract: Botulinum neurotoxins (BoNTs) are a family of bacterial toxins with seven major serotypes (BoNT/A-G). The ability of these toxins to target and bind to motor nerve terminals is a key factor determining their potency and efficacy. Among these toxins, BoNT/B is one of the two types approved for medical and cosmetic uses. Besides binding to well-established receptors, an extended loop in the C-terminal receptor-binding domain (HC) of BoNT/B (HC/B) has been proposed to also contribute to toxin binding to neurons by interacting with lipid membranes (termed lipid-binding loop [LBL]). Analogous loops exist in the HCs of BoNT/C, D, G, and a chimeric toxin DC. However, it has been challenging to detect and characterize binding of LBLs to lipid membranes. Here, using the nanodisc system and biolayer interferometry assays, we find that HC/DC, C, and G, but not HC/B and HC/D, are capable of binding to receptor-free lipids directly, with HC/DC having the highest level of binding. Mutagenesis studies demonstrate the critical role of consecutive aromatic residues at the tip of the LBL for binding of HC/DC to lipid membranes. Taking advantage of this insight, we then create a "gain-of-function" mutant HC/B by replacing two nonaromatic residues at the tip of its LBL with tryptophan. Cocrystallization studies confirm that these two tryptophan residues do not alter the structure of HC/B or the interactions with its receptors. Such a mutated HC/B gains the ability to bind receptor-free lipid membranes and shows enhanced binding to cultured neurons. Finally, full-length BoNT/B containing two tryptophan mutations in its LBL, together with two additional mutations (E1191M/S1199Y) that increase binding to human receptors, is produced and evaluated in mice in vivo using Digit Abduction Score assays. This mutant toxin shows enhanced efficacy in paralyzing local muscles at the injection site and lower systemic diffusion, thus extending both safety range and duration of paralysis compared with the control BoNT/B. These findings establish a mechanistic understanding of LBL-lipid interactions and create a modified BoNT/B with improved therapeutic efficacy.	Mar 2020
I04-1-Macromolecular Crystallography (fixed wavelength)	Structural basis for the interaction of the chaperone Cbp3 with newly synthesized cytochrome b during mitochondrial respiratory chain assembly Mama Ndi , Geoffrey Masuyer , Hannah Dawitz , Andreas Carlström , Mirco Michel , Arne Elofsson , Mikaela Rapp , Pal Stenmark , Martin Ott Journal Of Biological Chemistry DOI: 10.1074/jbc.RA119.010483 Diamond Proposal Number(s): [11265] Open Access Show Abstract ▼ Abstract: Assembly of the mitochondrial respiratory chain requires the coordinated synthesis of mitochondrial and nuclear encoded subunits, redox co-factor acquisition, and correct joining of the subunits to form functional complexes. The conserved Cbp3–Cbp6 chaperone complex binds newly synthesized cytochrome b and supports the ordered acquisition of the heme co-factors. Moreover, it functions as a translational activator by interacting with the mitoribosome. Cbp3 consists of two distinct domains, an N-terminal domain present in mitochondrial Cbp3 homologs, and a highly conserved C-terminal domain comprising a ubiquinol–cytochrome c chaperone region. Here, we solved the crystal structure of this C-terminal domain from a bacterial homolog at 1.4 Å resolution, revealing a unique all-helical fold. This structure allowed mapping of the interaction sites of yeast Cbp3 with Cbp6 and cytochrome b via site-specific photo-crosslinking. We propose that mitochondrial Cbp3 homologs carry an N-terminal extension that positions the conserved C-terminal domain at the ribosomal tunnel exit for an efficient interaction with its substrate, the newly synthesized cytochrome b protein.	Sep 2019
I03-Macromolecular Crystallography	Crystal structure of the catalytic domain of the Weissela oryzae botulinum‐like toxin Sara Kosenina , Geoffrey Masuyer , Sicai Zhang , Min Dong , Pal Stenmark Febs Letters DOI: 10.1002/1873-3468.13446 Diamond Proposal Number(s): [15806] Show Abstract ▼ Abstract: Botulinum neurotoxins (BoNTs) are the most potent toxins known. So far, eight serotypes have been identified that all act as zinc‐dependent endopeptidases targeting SNARE proteins and inhibiting the release of neurotransmitters. Recently, the first botulinum toxin‐like protein was identified outside the Clostridial genus, designated BoNT/Wo in the genome of Weissella oryzae. Here, we report the 1.6 Å X‐ray crystal structure of the light chain of BoNT/Wo (LC/Wo). LC/Wo presents the core fold common to BoNTs but has an unusually wide, open, and negatively charged catalytic pocket, with an additional Ca2+ ion besides the zinc ion and a unique ß‐hairpin motif. The structural information will help establish the substrate profile of BoNT/Wo and help our understanding of how BoNT evolved.	May 2019
I02-Macromolecular Crystallography I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength)	Engineered botulinum neurotoxin B with improved binding to human receptors has enhanced efficacy in preclinical models Mark Elliott , Christine Favre-Guilmard , Sai Man Liu , Jacquie Maignel , Geoffrey Masuyer , Matthew Beard , Christopher Boone , Denis Carré , Mikhail Kalinichev , Stephane Lezmi , Imran Mir , Camille Nicoleau , Shilpa Palan , Cindy Perier , Elsa Raban , Sicai Zhang , Min Dong , Pal Stenmark , Johannes Krupp Science Advances 5 DOI: 10.1126/sciadv.aau7196 Diamond Proposal Number(s): [11265, 15806] Open Access Show Abstract ▼ Abstract: Although botulinum neurotoxin serotype A (BoNT/A) products are common treatments for various disorders, there is only one commercial BoNT/B product, whose low potency, likely stemming from low affinity toward its human receptor synaptotagmin 2 (hSyt2), has limited its therapeutic usefulness. We express and characterize two full-length recombinant BoNT/B1 proteins containing designed mutations E1191M/S1199Y (rBoNT/B1MY) and E1191Q/S1199W (rBoNT/B1QW) that enhance binding to hSyt2. In preclinical models including human-induced pluripotent stem cell neurons and a humanized transgenic mouse, this increased hSyt2 affinity results in high potency, comparable to that of BoNT/A. Last, we solve the cocrystal structure of rBoNT/B1MY in complex with peptides of hSyt2 and its homolog hSyt1. We demonstrate that neuronal surface receptor binding limits the clinical efficacy of unmodified BoNT/B and that modified BoNT/B proteins have promising clinical potential.	Jan 2019
I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Small-molecule inhibitor of OGG1 suppresses proinflammatory gene expression and inflammation Torkild Visnes , Armando Cázares-Körner , Wenjing Hao , Olov Wallner , Geoffrey Masuyer , Olga Loseva , Oliver Mortusewicz , Elisée Wiita , Antonio Sarno , Aleksandr Manoilov , Juan Astorga-Wells , Ann-Sofie Jemth , Lang Pan , Kumar Sanjiv , Stella Karsten , Camilla Gokturk , Maurice Grube , Evert J. Homan , Bishoy M. F. Hanna , Cynthia B. J. Paulin , Therese Pham , Azita Rasti , Ulrika Warpman Berglund , Catharina Von Nicolai , Carlos Benitez-Buelga , Tobias Koolmeister , Dag Ivanic , Petar Iliev , Martin Scobie , Hans E. Krokan , Pawel Baranczewski , Per Artursson , Mikael Altun , Annika Jenmalm Jensen , Christina Kalderén , Xueqing Ba , Roman A. Zubarev , Pal Stenmark , Istvan Boldogh , Thomas Helleday Science 362, 834 - 839 DOI: 10.1126/science.aar8048 Diamond Proposal Number(s): [15806] Show Abstract ▼ Abstract: The onset of inflammation is associated with reactive oxygen species and oxidative damage to macromolecules like 7,8-dihydro-8-oxoguanine (8-oxoG) in DNA. Because 8-oxoguanine DNA glycosylase 1 (OGG1) binds 8-oxoG and because Ogg1-deficient mice are resistant to acute and systemic inflammation, we hypothesized that OGG1 inhibition may represent a strategy for the prevention and treatment of inflammation. We developed TH5487, a selective active-site inhibitor of OGG1, which hampers OGG1 binding to and repair of 8-oxoG and which is well tolerated by mice. TH5487 prevents tumor necrosis factor–α–induced OGG1-DNA interactions at guanine-rich promoters of proinflammatory genes. This, in turn, decreases DNA occupancy of nuclear factor κB and proinflammatory gene expression, resulting in decreased immune cell recruitment to mouse lungs. Thus, we present a proof of concept that targeting oxidative DNA repair can alleviate inflammatory conditions in vivo.	Nov 2018
I02-Macromolecular Crystallography	Structural characterisation of the catalytic domain of botulinum neurotoxin X - high activity and unique substrate specificity Geoffrey Masuyer , Sicai Zhang , Sulyman Barkho , Yi Shen , Linda Henriksson , Sara Košenina , Min Dong , Pal Stenmark Scientific Reports 8 DOI: 10.1038/s41598-018-22842-4 Diamond Proposal Number(s): [11265] Open Access Show Abstract ▼ Abstract: Botulinum neurotoxins (BoNTs) are among the most potent toxins known and are also used to treat an increasing number of medical disorders. There are seven well-established serotypes (BoNT/A-G), which all act as zinc-dependent endopeptidases targeting specific members of the SNARE proteins required for synaptic vesicle exocytosis in neurons. A new toxin serotype, BoNT/X, was recently identified. It cleaves not only the canonical targets, vesicle associated membrane proteins (VAMP) 1/2/3 at a unique site, but also has the unique ability to cleave VAMP4/5 and Ykt6. Here we report the 1.35 Å X-ray crystal structure of the light chain of BoNT/X (LC/X). LC/X shares the core fold common to all other BoNTs, demonstrating that LC/X is a bona fide member of BoNT-LCs. We found that access to the catalytic pocket of LC/X is more restricted, and the regions lining the catalytic pocket are not conserved compared to other BoNTs. Kinetic studies revealed that LC/X cleaves VAMP1 with a ten times higher efficiency than BoNT/B and the tetanus neurotoxin. The structural information provides a molecular basis to understand the convergence/divergence between BoNT/X and other BoNTs, to develop effective LC inhibitors, and to engineer new scientific tools and therapeutic toxins targeting distinct SNARE proteins in cells.	Mar 2018
B21-High Throughput SAXS I04-1-Macromolecular Crystallography (fixed wavelength) Krios I-Titan Krios I at Diamond	The structure of the tetanus toxin reveals pH‐mediated domain dynamics Geoffrey Masuyer , Julian Conrad , Pal Stenmark Embo Reports DOI: 10.15252/embr.201744198 Diamond Proposal Number(s): [11265] Show Abstract ▼ Abstract: The tetanus neurotoxin (TeNT) is a highly potent toxin produced by Clostridium tetani that inhibits neurotransmission of inhibitory interneurons, causing spastic paralysis in the tetanus disease. TeNT differs from the other clostridial neurotoxins by its unique ability to target the central nervous system by retrograde axonal transport. The crystal structure of the tetanus toxin reveals a “closed” domain arrangement stabilised by two disulphide bridges, and the molecular details of the toxin's interaction with its polysaccharide receptor. An integrative analysis combining X-ray crystallography, solution scattering and single particle electron cryo-microscopy reveals pH-mediated domain rearrangements that may give TeNT the ability to adapt to the multiple environments encountered during intoxication, and facilitate binding to distinct receptors.	Jun 2017

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