I03-Macromolecular Crystallography
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Emma Zsófia Aletta
Nagy
,
Souad Diana
Tork
,
Pauline A.
Lang
,
Alina
Filip
,
Florin Dan
Irimie
,
László
Poppe
,
Monica Ioana
Toşa
,
Christopher J.
Schofield
,
Jurgen
Brem
,
Csaba
Paizs
,
Laszlo Csaba
Bencze
Diamond Proposal Number(s):
[19458]
Abstract: Modification of the hydrophobic binding pocket of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) enables increased activity and selectivity towards phenylalanines and cinnamic acids mono-substituted with both electron donating (-CH3, -OCH3) and electron withdrawing (-CF3, -Br) groups at all positions (o-, m-, p-) of their aromatic ring. The results reveal specific residues involved in accommodating substituents at o-, m-, p-positions of the substrate’s phenyl ring. The predicted interactions were validated by crystallographic analysis of the binding mode of para-methoxy cinnamic acid complexed at the active site of PcPAL. The biocatalytic utility of the tailored PcPAL mutants was demonstrated by the efficient preparative scale synthesis of (S)-m-bromo-phenylalanine (ee: > 99%, yield: 60%) and (R)-p-methyl-phenylalanine (ee: 97%, yield: 49%), using the corresponding ammonia addition and ammonia elimination reactions catalyzed by the L134A and I460V PcPAL variants, respectively. Overall, the results reveal the potential for structure based protein engineering of PALs to provide enzymes with enhanced catalytic properties and which are specifically tailored for differently substituted phenylalanine analogues of high synthetic value.
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Aug 2019
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I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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Alen
Krajnc
,
Jurgen
Brem
,
Philip
Hinchliffe
,
Karina
Calvopina
,
Tharindi
Panduwawala
,
Pauline A.
Lang
,
Jos J. A. G.
Kamps
,
Jonathan M.
Tyrell
,
Emma
Widlake
,
Benjamin G.
Saward
,
Timothy R.
Walsh
,
James
Spencer
,
Christopher J.
Schofield
Diamond Proposal Number(s):
[17212, 18069]
Abstract: The bicyclic boronate VNRX-5133 is a new type of β-lactamase inhibitor in clinical development. We report that VNRX-5133 inhibits serine-β-lactamases (SBLs) and some clinically important metallo-β-lactamases (MBLs), including NDM-1 and VIM-1/2. VNRX-5133 activity against IMP-1 and tested B2/B3 MBLs was lower/not observed. Crystallography reveals how VNRX-5133 binds to the class D SBL OXA-10 and NDM-1. The crystallographic results highlight the ability of bicyclic boronates to inhibit SBLs and MBLs via binding of a tetrahedral (sp3) boron species. The structures imply conserved binding of the bicyclic core with SBLs/MBLs. With NDM-1, by crystallography we observed an unanticipated VNRX-5133 binding mode involving cyclization of its acylamino oxygen onto the boron of the bicyclic core. Different side-chain-dependent binding modes for bicyclic boronates imply scope for optimisation. The results further support the ‘high energy intermediate’ analogue approach for broad-spectrum β-lactamase inhibitor development and highlight the ability of boron-inhibitors to interchange between different hybridization states / binding modes.
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Aug 2019
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Diamond Proposal Number(s):
[12346]
Abstract: Bacterial production of β‐lactamases with carbapenemase activity is a global health threat. The active sites of class D carbapenemases such as OXA‐48, which is of major clinical importance, uniquely contain a carbamylated lysine residue which is essential for catalysis. Although there is significant interest in characterizing this post‐translational modification, and it is a promising inhibition target, protein carbamylation is challenging to monitor in solution. We report the use of 19F‐NMR spectroscopy to monitor the carbamylation state of 19F‐labelled OXA‐48. This method was used to investigate the interactions of OXA‐48 with clinically used serine β‐ lactamase inhibitors, including avibactam and vaborbactam. Crystallographic studies on 19F‐labelled OXA‐48 provide a structural rationale for the sensitivity of the 19F‐label to active site interactions. The overall results demonstrate the use of 19F‐NMR to monitor reversible covalent post‐translational modifications.
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Jul 2019
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I02-Macromolecular Crystallography
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Diamond Proposal Number(s):
[12346]
Abstract: JmjC domain containing protein 6 (JMJD6) is a 2-oxoglutarate (2OG)-dependent oxygenase linked to various cellular processes including splicing regulation, histone modification, transcriptional pause release, hypoxia sensing, and cancer. JMJD6 is reported to catalyze hydroxylation of lysine residue(s) of histones, the tumor suppressor protein p53, and splicing regulatory proteins, including u2 small nuclear ribonucleoprotein auxiliary factor 65-kDa subunit (U2AF65). JMJD6 is also reported to catalyze N-demethylation of N-methylated (both mono- and di-methylated) arginine residues of histones, and other proteins including heat shock protein 70 (HSP70), oestrogen receptor α (ERα) and RNA helicase A. Here we report MS- and NMR-based kinetic assays employing purified JMJD6 and multiple substrate fragment sequences, the results of which support the assignment of purified JMJD6 as a lysyl hydroxylase. By contrast, we did not observe N-methyl arginyl N-demethylation with purified JMJD6. Biophysical analyses including crystallographic analyses of JMJD6Δ344-403 in complex with iron and 2OG supported its assignment as a lysyl-hydroxylase rather than an N-methyl arginyl-demethylase. The screening results supported some, but not all, of the assigned JMJD6 substrates and identified other potential JMJD6 substrates. We envision these results will be useful in cellular and biological work on the substrates and functions of JMJD6 and in the development of selective inhibitors of human 2OG oxygenases.
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May 2019
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I04-Macromolecular Crystallography
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Samuel T.
Cahill
,
Jonathan M.
Tyrrell
,
Iva
Hopkins Navratilova
,
Karina
Calvopina
,
Sean W.
Robinson
,
Christopher T.
Lohans
,
Michael A.
Mcdonough
,
Ricky
Cain
,
Colin W. G.
Fishwick
,
Matthew B.
Avison
,
Timothy R.
Walsh
,
Christopher J.
Schofield
,
Jurgen
Brem
Abstract: Background: The β-lactam antibiotics represent the most successful drug class for treatment of bacterial infections. Resistance to them, importantly via production of β-lactamases, which collectively are able to hydrolyse all classes of β-lactams, threatens their continued widespread use. Bicyclic boronates show potential as broad spectrum inhibitors of the mechanistically distinct serine- (SBL) and metallo- (MBL) β-lactamase families. Methods: Using biophysical methods, including crystallographic analysis, we have investigated the binding mode of bicyclic boronates to clinically important β-lactamases. Induction experiments and agar-based MIC screening against MDR-Enterobacteriaceae (n = 132) were used to evaluate induction properties and the in vitro efficacy of a bicyclic boronate in combination with meropenem. Results: Crystallographic analysis of a bicyclic boronate in complex with AmpC from Pseudomonas aeruginosa reveals it binds to form a tetrahedral boronate species. Microbiological studies on the clinical coverage (in combination with meropenem) and induction of β-lactamases by bicyclic boronates further support the promise of such compounds as broad spectrum β-lactamase inhibitors. Conclusions: Together with reported studies on the structural basis of their inhibition of class A, B and D β-lactamases, biophysical studies, including crystallographic analysis, support the proposal that bicyclic boronates mimic tetrahedral intermediates common to SBL and MBL catalysis. General significance: Bicyclic boronates are a new generation of broad spectrum inhibitors of both SBLs and MBLs.
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Apr 2019
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I04-1-Macromolecular Crystallography (fixed wavelength)
I24-Microfocus Macromolecular Crystallography
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Faraz
Shaikh
,
Yuguang
Zhao
,
Luis
Alvarez
,
Maria
Iliopoulou
,
Christopher Thomas
Lohans
,
Christopher J.
Schofield
,
Sergi
Padilla-parra
,
Shirley W. I.
Siu
,
Elizabeth
Fry
,
Jingshan
Ren
,
David I.
Stuart
Diamond Proposal Number(s):
[10627]
Abstract: Potent Ebolavirus (EBOV) inhibitors will help to curtail outbreaks such as that which occurred in 2014-16 in West Africa. EBOV has on its surface a single glycoprotein (GP) critical for viral entry and membrane fusion. Recent high resolution complexes of EBOV GP with a variety of approved drugs revealed that binding to a common cavity prevented fusion of the virus and endosomal membranes, inhibiting virus infection. We performed docking experiments, screening a database of natural compounds to identify those likely to bind at this site. Using both inhibition assays of HIV-1-derived pseudovirus cell entry and structural analyses of the complexes of the compounds with GP we show here that two of these compounds attach in the common binding cavity, out of eight tested. In both cases two molecules bind in the cavity. The two compounds are chemically similar but the tighter binder has an additional chlorine atom that forms good halogen bonds to the protein and achieves an IC50 of 50 nM, making it the most potent GP-binding EBOV inhibitor yet identified, validating our screening approach for the discovery of novel anti-viral compounds.
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Feb 2019
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I04-Macromolecular Crystallography
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Open Access
Abstract: Replication-dependent (RD) core histone mRNA produced during S-phase is the only known metazoan protein-coding mRNA presenting a 3' stem-loop instead of the otherwise universal polyA tail. A metallo β-lactamase (MBL) fold enzyme, cleavage and polyadenylation specificity factor 73 (CPSF73), is proposed to be the sole endonuclease responsible for 3' end processing of both mRNA classes. We report cellular, genetic, biochemical, substrate selectivity, and crystallographic studies providing evidence that an additional endoribonuclease, MBL domain containing protein 1 (MBLAC1), is selective for 3' processing of RD histone pre-mRNA during the S-phase of the cell cycle. Depletion of MBLAC1 in cells significantly affects cell cycle progression thus identifying MBLAC1 as a new type of S-phase-specific cancer target.
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Dec 2018
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I02-Macromolecular Crystallography
I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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Ramya
Salimraj
,
Philip
Hinchliffe
,
Magda
Kosmopoulou
,
Jonathan M.
Tyrrell
,
Jurgen
Brem
,
Sander S.
Van Berkel
,
Anil
Verma
,
Raymond J.
Owens
,
Michael A.
Mcdonough
,
Timothy R.
Walsh
,
Christopher J.
Schofield
,
James
Spencer
Diamond Proposal Number(s):
[313]
Abstract: Metallo‐β‐Lactamases (MBLs) protect bacteria from almost all β‐lactam antibiotics. VIM enzymes are among the most clinically important MBLs, with VIM‐1 increasing in carbapenem‐resistant Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae) that are amongst the hardest bacterial pathogens to treat. VIM enzymes display sequence variation at residues (224 and 228) that in related MBLs are conserved and participate in substrate binding. How they accommodate this variability, while retaining catalytic efficiency against a broad substrate range, has remained unclear. Here we present crystal structures of VIM‐1 and its complexes with a substrate‐mimicking thioenolate inhibitor, ML302F, that restores meropenem activity against a range of VIM‐1 producing clinical strains, and the hydrolysed product of the carbapenem meropenem. Comparison of these two structures identifies a water‐mediated hydrogen bond, between the carboxylate group of substrate/inhibitor and the backbone carbonyl of the active site zinc ligand Cys221, that is common to both complexes. Structural comparisons show that the responsible Cys221‐bound water is observed in all known VIM structures, participates in carboxylate binding with other inhibitor classes, and thus effectively replicates the role of the conserved Lys224 in analogous complexes with other MBLs. These results provide a mechanism for substrate binding that permits the variation at positions 224 and 228 that is a hallmark of VIM MBLs.
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Nov 2018
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I02-Macromolecular Crystallography
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Diamond Proposal Number(s):
[1230]
Open Access
Abstract: Background: In humans and other animals, the chronic hypoxic response is mediated by hypoxia inducible transcription factors (HIFs) which regulate the expression of genes that counteract the effects of limiting oxygen. Prolyl hydroxylases (PHDs) act as hypoxia sensors for the HIF system in organisms ranging from humans to the simplest animal Trichoplax adhaerens.
Methods: We report structural and biochemical studies on the T. adhaerens HIF prolyl hydroxylase (TaPHD) that inform about the evolution of hypoxia sensing in animals.
Results: High resolution crystal structures (≤1.3 Å) of TaPHD, with and without its HIFα substrate, reveal remarkable conservation of key active site elements between T. adhaerens and human PHDs, which also manifest in kinetic comparisons.
Conclusion: Conserved structural features of TaPHD and human PHDs include those apparently enabling the slow binding/reaction of oxygen with the active site Fe(II), the formation of a stable 2-oxoglutarate complex, and a stereoelectronically promoted change in conformation of the hydroxylated proline-residue. Comparison of substrate selectivity between the human PHDs and TaPHD provides insights into the selectivity determinants of HIF binding by the PHDs, and into the evolution of the multiple HIFs and PHDs present in higher animals.
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Nov 2018
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Diamond Proposal Number(s):
[18069]
Open Access
Abstract: N‐Methylation of lysyl residues is widely observed on histone proteins. Using isolated enzymes, we report mechanistic and structural studies on histone lysine demethylase (KDM)‐catalysed demethylation of Nε‐methylated lysine 26 on histone 1 isotype 4 (H1.4). The results reveal that methylated H1.4K26 is a substrate for all members of the KDM4 subfamily and that KDM4A‐catalysed demethylation of H1.4K26me3 peptide is similarly efficient to that of H3K9me3. Crystallographic studies of an H1.4K26me3:KDM4A complex reveal a conserved binding geometry to that of H3K9me3. In the light of the high activity of the KDM4s on this mark, our results suggest JmjC KDM‐catalysed demethylation of H1.4K26 may be as prevalent as demethylation on the H3 tail and warrants further investigation in cells.
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Oct 2018
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