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Xiaojie
Yu
,
Christian M.
Orr
,
H. T. Claude
Chan
,
Sonya
James
,
Christine A.
Penfold
,
Jinny
Kim
,
Tatyana
Inzhelevskaya
,
C. Ian
Mockridge
,
Kerry L.
Cox
,
Jonathan W.
Essex
,
Ivo
Tews
,
Martin J.
Glennie
,
Mark S.
Cragg
Abstract: Antibody responses during infection and vaccination typically undergo affinity maturation to achieve high-affinity binding for efficient neutralization of pathogens1,2. Similarly, high affinity is routinely the goal for therapeutic antibody generation. However, in contrast to naturally occurring or direct-targeting therapeutic antibodies, immunomodulatory antibodies, which are designed to modulate receptor signalling, have not been widely examined for their affinity–function relationship. Here we examine three separate immunologically important receptors spanning two receptor superfamilies: CD40, 4-1BB and PD-1. We show that low rather than high affinity delivers greater activity through increased clustering. This approach delivered higher immune cell activation, in vivo T cell expansion and antitumour activity in the case of CD40. Moreover, an inert anti-4-1BB monoclonal antibody was transformed into an agonist. Low-affinity variants of the clinically important antagonistic anti-PD-1 monoclonal antibody nivolumab also mediated more potent signalling and affected T cell activation. These findings reveal a new paradigm for augmenting agonism across diverse receptor families and shed light on the mechanism of antibody-mediated receptor signalling. Such affinity engineering offers a rational, efficient and highly tuneable solution to deliver antibody-mediated receptor activity across a range of potencies suitable for translation to the treatment of human disease.
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Feb 2023
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I03-Macromolecular Crystallography
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Diamond Proposal Number(s):
[29835]
Open Access
Abstract: Enzymatic cleavage of IgG antibodies is a common strategy used by pathogenic bacteria to ablate immune effector function. The Streptococcus pyogenes bacterium secretes the protease IdeS and the glycosidase EndoS, which specifically catalyse cleavage and deglycosylation of human IgG, respectively. IdeS has received clinical approval for kidney transplantation in hypersensitised individuals, while EndoS has found application in engineering antibody glycosylation. We present crystal structures of both enzymes in complex with their IgG1 Fc substrate, which was achieved using Fc engineering to disfavour preferential Fc crystallisation. The IdeS protease displays extensive Fc recognition and encases the antibody hinge. Conversely, the glycan hydrolase domain in EndoS traps the Fc glycan in a “flipped-out” conformation, while additional recognition of the Fc peptide is driven by the so-called carbohydrate binding module. In this work, we reveal the molecular basis of antibody recognition by bacterial enzymes, providing a template for the development of next-generation enzymes.
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Dec 2022
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I24-Microfocus Macromolecular Crystallography
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Tadeo
Moreno-Chicano
,
Leiah M.
Carey
,
Danny
Axford
,
John H.
Beale
,
R. Bruce
Doak
,
Helen M. E.
Duyvesteyn
,
Ali
Ebrahim
,
Robert W.
Henning
,
Diana C. F.
Monteiro
,
Dean A.
Myles
,
Shigeki
Owada
,
Darren A.
Sherrell
,
Megan L.
Straw
,
Vukica
Šrajer
,
Hiroshi
Sugimoto
,
Kensuke
Tono
,
Takehiko
Tosha
,
Ivo
Tews
,
Martin
Trebbin
,
Richard W.
Strange
,
Kevin L.
Weiss
,
Jonathan A. R.
Worrall
,
Flora
Meilleur
,
Robin L.
Owen
,
Reza A.
Ghiladi
,
Michael A.
Hough
Diamond Proposal Number(s):
[14493]
Open Access
Abstract: Room-temperature macromolecular crystallography allows protein structures to be determined under close-to-physiological conditions, permits dynamic freedom in protein motions and enables time-resolved studies. In the case of metalloenzymes that are highly sensitive to radiation damage, such room-temperature experiments can present challenges, including increased rates of X-ray reduction of metal centres and site-specific radiation-damage artefacts, as well as in devising appropriate sample-delivery and data-collection methods. It can also be problematic to compare structures measured using different crystal sizes and light sources. In this study, structures of a multifunctional globin, dehaloperoxidase B (DHP-B), obtained using several methods of room-temperature crystallographic structure determination are described and compared. Here, data were measured from large single crystals and multiple microcrystals using neutrons, X-ray free-electron laser pulses, monochromatic synchrotron radiation and polychromatic (Laue) radiation light sources. These approaches span a range of 18 orders of magnitude in measurement time per diffraction pattern and four orders of magnitude in crystal volume. The first room-temperature neutron structures of DHP-B are also presented, allowing the explicit identification of the hydrogen positions. The neutron data proved to be complementary to the serial femtosecond crystallography data, with both methods providing structures free of the effects of X-ray radiation damage when compared with standard cryo-crystallography. Comparison of these room-temperature methods demonstrated the large differences in sample requirements, data-collection time and the potential for radiation damage between them. With regard to the structure and function of DHP-B, despite the results being partly limited by differences in the underlying structures, new information was gained on the protonation states of active-site residues which may guide future studies of DHP-B.
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Sep 2022
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I03-Macromolecular Crystallography
I23-Long wavelength MX
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Christian M.
Orr
,
Hayden
Fisher
,
Xiaojie
Yu
,
Claude H.-T.
Chan
,
Yunyun
Gao
,
Patrick J.
Duriez
,
Steven G.
Booth
,
Isabel
Elliott
,
Tatyana
Inzhelevskaya
,
Ian
Mockridge
,
Christine A.
Penfold
,
Armin
Wagner
,
Martin J.
Glennie
,
Ann L.
White
,
Jonathan W.
Essex
,
Arwen R.
Pearson
,
Mark S.
Cragg
,
Ivo
Tews
Diamond Proposal Number(s):
[22563]
Open Access
Abstract: Antibodies protect from infection, underpin successful vaccines and elicit therapeutic responses in otherwise untreatable cancers and autoimmune conditions. The human IgG2 isotype displays a unique capacity to undergo disulfide shuffling in the hinge region, leading to modulation of its ability to drive target receptor signaling (agonism) in a variety of important immune receptors, through hitherto unexplained molecular mechanisms. To address the underlying process and reveal how hinge disulfide orientation affects agonistic activity, we generated a series of cysteine to serine exchange variants in the hinge region of the clinically relevant monoclonal antibody ChiLob7/4, directed against the key immune receptor CD40. We report how agonistic activity varies with disulfide pattern and is afforded by the presence of a disulfide crossover between F(ab) arms in the agonistic forms, independently of epitope, as observed in the determined crystallographic structures. This structural “switch” affects directly on antibody conformation and flexibility. Small-angle x-ray scattering and ensemble modeling demonstrated that the least flexible variants adopt the fewest conformations and evoke the highest levels of receptor agonism. This covalent change may be amenable for broad implementation to modulate receptor signaling in an epitope-independent manner in future therapeutics.
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Jul 2022
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Open Access
Abstract: The Pdx1 enzyme catalyses condensation of two carbohydrates and ammonia to form pyridoxal 5-phosphate (PLP) via an imine relay mechanism of carbonyl intermediates. The I333 intermediate characterised here using structural, UV-vis absorption spectroscopy and mass spectrometry analyses rationalises stereoselective deprotonation and subsequent substrate assisted phosphate elimination, central to PLP biosynthesis.
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Feb 2022
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Open Access
Abstract: PAS domains are omnipresent building blocks of multidomain proteins in all domains of life. Bacteria possess a variety of PAS domains in intracellular proteins and the related Cache domains in periplasmic or extracellular proteins. PAS and Cache domains are predominant in sensory systems, often carry cofactors or bind ligands, and serve as dimerization domains in protein association. To aid our understanding of the wide distribution of these domains, we analyzed the proteome of the opportunistic human pathogen Pseudomonas aeruginosa PAO1 in silico. The ability of this bacterium to survive under different environmental conditions, to switch between planktonic and sessile/biofilm lifestyle, or to evade stresses, notably involves c-di-GMP regulatory proteins or depends on sensory pathways involving multidomain proteins that possess PAS or Cache domains. Maximum likelihood phylogeny was used to group PAS and Cache domains on the basis of amino acid sequence. Conservation of cofactor- or ligand-coordinating amino acids aided by structure-based comparison was used to inform function. The resulting classification presented here includes PAS domains that are candidate binders of carboxylic acids, amino acids, fatty acids, flavin adenine dinucleotide (FAD), 4-hydroxycinnamic acid, and heme. These predictions are put in context to previously described phenotypic data, often generated from deletion mutants. The analysis predicts novel functions for sensory proteins and sheds light on functional diversification in a large set of proteins with similar architecture.
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Dec 2021
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I24-Microfocus Macromolecular Crystallography
Data acquisition
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Open Access
Abstract: Serial data collection is a relatively new technique for synchrotron users. A user manual for fixed target data collection at I24, Diamond Light Source is presented with detailed step-by-step instructions, figures, and videos for smooth data collection.
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Feb 2021
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|
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Marina
Lucic
,
Dimitri
Svistunenko
,
Michael
Wilson
,
Amanda
Chaplin
,
Bradley
Davy
,
Ali
Ebrahim
,
Danny
Axford
,
Takehiko
Tosha
,
Hiroshi
Sugimoto
,
Shigeki
Owada
,
Florian
Dworkowski
,
Ivo
Tews
,
Robin
Owen
,
Michael
Hough
,
Jonathan A. R.
Worrall
Open Access
Abstract: Obtaining structures of intact redox states of metal centres derived from zero dose X‐ray crystallography can advance our mechanistic understanding of metalloenzymes. In dye‐decolourising heme peroxidases (DyPs), controversy exists regarding the mechanistic role of the distal heme residues, aspartate and arginine, in the heterolysis of peroxide to form the catalytic intermediate compound I (Fe IV =O and a porphyrin cation radical). Using serial femtosecond X‐ray (SFX) crystallography, we have determined the pristine structures of the Fe III and Fe IV =O redox states of a B‐type DyP. These structures reveal a water‐free distal heme site, which together with the presence of an asparagine, infer the use of the distal arginine as a catalytic base. A combination of mutagenesis and kinetic studies corroborate such a role. Our SFX approach thus provides unique insight into how the distal heme site of DyPs can be tuned to select aspartate or arginine for the rate enhancement of peroxide heterolysis.
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Aug 2020
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B21-High Throughput SAXS
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Xiaojie
Yu
,
H.t. Claude
Chan
,
Hayden
Fisher
,
Christine A.
Penfold
,
Jinny
Kim
,
Tatyana
Inzhelevskaya
,
C. Ian
Mockridge
,
Ruth R.
French
,
Patrick J.
Duriez
,
Leon R.
Douglas
,
Vikki
English
,
J. Sjef
Verbeek
,
Ann L.
White
,
Ivo
Tews
,
Martin J.
Glennie
,
Mark S.
Cragg
Diamond Proposal Number(s):
[21035]
Open Access
Abstract: Anti-CD40 monoclonal antibodies (mAbs) comprise agonists and antagonists, which display promising therapeutic activities in cancer and autoimmunity, respectively. We previously showed that epitope and isotype interact to deliver optimal agonistic anti-CD40 mAbs. The impact of Fc engineering on antagonists, however, remains largely unexplored. Here, we show that clinically relevant antagonists used for treating autoimmune conditions can be converted into potent FcγR-independent agonists with remarkable antitumor activity by isotype switching to hIgG2. One antagonist is converted to a super-agonist with greater potency than previously reported highly agonistic anti-CD40 mAbs. Such conversion is dependent on the unique disulfide bonding properties of the hIgG2 hinge. This investigation highlights the transformative capacity of the hIgG2 isotype for converting antagonists to agonists to treat cancer.
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May 2020
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Open Access
Abstract: In Pseudomonas aeruginosa, the transition between planktonic and biofilm lifestyles is modulated by the intracellular secondary messenger cyclic dimeric-GMP (c-di-GMP) in response to environmental conditions. Here, we used gene deletions to investigate how the environmental stimulus nitric oxide (NO) is linked to biofilm dispersal, focusing on biofilm dispersal phenotype from proteins containing putative c-di-GMP turnover and Per-Arnt-Sim (PAS) sensory domains. We document opposed physiological roles for the genes ΔrbdA and Δpa2072 that encode proteins with identical domain structure: while ΔrbdA showed elevated c-di-GMP levels, restricted motility and promoted biofilm formation, c-di-GMP levels were decreased in Δpa2072, and biofilm formation was inhibited, compared to wild type. A second pair of genes, ΔfimX and ΔdipA, were selected on the basis of predicted impaired c-di-GMP turnover function: ΔfimX showed increased, ΔdipA decreased NO induced biofilm dispersal, and the genes effected different types of motility, with reduced twitching for ΔfimX and reduced swimming for ΔdipA. For all four deletion mutants we find that NO-induced biomass reduction correlates with increased NO-driven swarming, underlining a significant role for this motility in biofilm dispersal. Hence P. aeruginosa is able to differentiate c-di-GMP output using structurally highly related proteins that can contain degenerate c-di-GMP turnover domains.
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Apr 2020
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