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Instruments / Technical Area	Publication Details	Published
	Structure of a ribonucleotide reductase R2 protein radical Hugo Lebrette , Vivek Srinivas , Juliane John , Oskar Aurelius , Rohit Kumar , Daniel Lundin , Aaron S. Brewster , Asmit Bhowmick , Abhishek Sirohiwal , In-Sik Kim , Sheraz Gul , Cindy Pham , Kyle D. Sutherlin , Philipp Simon , Agata Butryn , Pierre Aller , Allen M. Orville , Franklin D. Fuller , Roberto Alonso-Mori , Alexander Batyuk , Nicholas K. Sauter , Vittal K. Yachandra , Junko Yano , Ville R. I. Kaila , Britt-Marie Sjöberg , Jan Kern , Katarina Roos , Martin Högbom Science 382, 109 - 113 DOI: 10.1126/science.adh8160 Show Abstract ▼ Abstract: Aerobic ribonucleotide reductases (RNRs) initiate synthesis of DNA building blocks by generating a free radical within the R2 subunit; the radical is subsequently shuttled to the catalytic R1 subunit through proton-coupled electron transfer (PCET). We present a high-resolution room temperature structure of the class Ie R2 protein radical captured by x-ray free electron laser serial femtosecond crystallography. The structure reveals conformational reorganization to shield the radical and connect it to the translocation path, with structural changes propagating to the surface where the protein interacts with the catalytic R1 subunit. Restructuring of the hydrogen bond network, including a notably short O–O interaction of 2.41 angstroms, likely tunes and gates the radical during PCET. These structural results help explain radical handling and mobilization in RNR and have general implications for radical transfer in proteins.	Oct 2023
	Redox-controlled reorganization and flavin strain within the ribonucleotide reductase R2b–NrdI complex monitored by serial femtosecond crystallography Juliane John , Oskar Aurelius , Vivek Srinivas , Patricia Saura , In-Sik Kim , Asmit Bhowmick , Philipp S. Simon , Medhanjali Dasgupta , Cindy Pham , Sheraz Gul , Kyle D. Sutherlin , Pierre Aller , Agata Butryn , Allen M. Orville , Mun Hon Cheah , Shigeki Owada , Kensuke Tono , Franklin D Fuller , Alexander Batyuk , Aaron S. Brewster , Nicholas K. Sauter , Vittal K Yachandra , Junko Yano , Ville R. I. Kaila , Jan Kern , Hugo Lebrette , Martin Högbom Elife 11 DOI: 10.7554/eLife.79226 Open Access Show Abstract ▼ Abstract: Redox reactions are central to biochemistry and are both controlled by and induce protein structural changes. Here, we describe structural rearrangements and crosstalk within the Bacillus cereus ribonucleotide reductase R2b–NrdI complex, a di-metal carboxylate-flavoprotein system, as part of the mechanism generating the essential catalytic free radical of the enzyme. Femtosecond crystallography at an X-ray free electron laser was utilized to obtain structures at room temperature in defined redox states without suffering photoreduction. Together with density functional theory calculations, we show that the flavin is under steric strain in the R2b–NrdI protein complex, likely tuning its redox properties to promote superoxide generation. Moreover, a binding site in close vicinity to the expected flavin O2 interaction site is observed to be controlled by the redox state of the flavin and linked to the channel proposed to funnel the produced superoxide species from NrdI to the di-manganese site in protein R2b. These specific features are coupled to further structural changes around the R2b–NrdI interaction surface. The mechanistic implications for the control of reactive oxygen species and radical generation in protein R2b are discussed.	Sep 2022
I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength)	Multitarget, selective compound design yields potent inhibitors of a kinetoplastid pteridine reductase 1 Ina Pöhner , Antonio Quotadamo , Joanna Panecka-Hofman , Rosaria Luciani , Matteo Santucci , Pasquale Linciano , Giacomo Landi , Flavio Di Pisa , Lucia Dello Iacono , Cecilia Pozzi , Stefano Mangani , Sheraz Gul , Gesa Witt , Bernhard Ellinger , Maria Kuzikov , Nuno Santarem , Anabela Cordeiro-Da-Silva , Maria P. Costi , Alberto Venturelli , Rebecca C. Wade Journal Of Medicinal Chemistry 51 DOI: 10.1021/acs.jmedchem.2c00232 Open Access Show Abstract ▼ Abstract: The optimization of compounds with multiple targets is a difficult multidimensional problem in the drug discovery cycle. Here, we present a systematic, multidisciplinary approach to the development of selective antiparasitic compounds. Computational fragment-based design of novel pteridine derivatives along with iterations of crystallographic structure determination allowed for the derivation of a structure–activity relationship for multitarget inhibition. The approach yielded compounds showing apparent picomolar inhibition of T. brucei pteridine reductase 1 (PTR1), nanomolar inhibition of L. major PTR1, and selective submicromolar inhibition of parasite dihydrofolate reductase (DHFR) versus human DHFR. Moreover, by combining design for polypharmacology with a property-based on-parasite optimization, we found three compounds that exhibited micromolar EC50 values against T. brucei brucei while retaining their target inhibition. Our results provide a basis for the further development of pteridine-based compounds, and we expect our multitarget approach to be generally applicable to the design and optimization of anti-infective agents.	Jun 2022
I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength) I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis Patrick Rabe , Jos J. A. G. Kamps , Kyle D. Sutherlin , James D. S. Linyard , Pierre Aller , Cindy C. Pham , Mikako Makita , Ian Clifton , Michael A. Mcdonough , Thomas M. Leissing , Denis Shutin , Pauline A. Lang , Agata Butryn , Jurgen Brem , Sheraz Gul , Franklin D. Fuller , In-Sik Kim , Mun Hon Cheah , Thomas Fransson , Asmit Bhowmick , Iris D. Young , Lee O'Riordan , Aaron S. Brewster , Ilaria Pettinati , Margaret Doyle , Yasumasa Joti , Shigeki Owada , Kensuke Tono , Alexander Batyuk , Mark S. Hunter , Roberto Alonso-Mori , Uwe Bergmann , Robin L. Owen , Nicholas K. Sauter , Timothy D. W. Claridge , Carol V. Robinson , Vittal K. Yachandra , Junko Yano , Jan F. Kern , Allen M. Orville , Christopher J. Schofield Science Advances 7 DOI: 10.1126/sciadv.abh0250 Diamond Proposal Number(s): [23459, 19458] Open Access Show Abstract ▼ Abstract: Isopenicillin N synthase (IPNS) catalyzes the unique reaction of L-δ-(α-aminoadipoyl)-L-cysteinyl-D-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts.	Aug 2021
	High resolution XFEL structure of the soluble methane monooxygenase hydroxylase complex with its regulatory component at ambient temperature in two oxidation states Vivek Srinivas , Rahul Banerjee , Hugo Lebrette , Jason C. Jones , Oskar Aurelius , In-Sik Kim , Cindy C. Pham , Sheraz Gul , Kyle Sutherlin , Asmit Bhowmick , Juliane John , Esra Bozkurt , Thomas Fransson , Pierre Aller , Agata Butryn , Isabel Bogacz , Philipp Stefan Simon , Stephen Keable , Alexander Britz , Kensuke Tono , Kyung-Sook Kim , Sang-Youn Park , Sang-Jae Lee , Jaehyun Park , Roberto Alonso-Mori , Franklin Fuller , Alexander Batyuk , Aaron S. Brewster , Uwe Bergmann , Nicholas Sauter , Allen M. Orville , Vittal K. Yachandra , Junko Yano , John D. Lipscomb , Jan F. Kern , Martin Högbom Journal Of The American Chemical Society DOI: 10.1021/jacs.0c05613 Show Abstract ▼ Abstract: Soluble methane monooxygenase (sMMO) is a multicomponent metalloenzyme that catalyzes the conversion of methane to methanol at ambient temperature using a nonheme, oxygen-bridged dinuclear iron cluster in the active site. Structural changes in the hydroxylase component (sMMOH) containing the diiron cluster caused by complex formation with a regulatory component (MMOB) and by iron reduction are important for the regulation of O2 activation and substrate hydroxylation. Structural studies of metalloenzymes using traditional synchrotron-based X-ray crystallography are often complicated by partial X-ray-induced photoreduction of the metal center, thereby obviating determination of the structure of pure oxidation states. Here microcrystals of the sMMOH:MMOB complex from Methylosinus trichosporium OB3b were serially exposed to X-ray free electron laser (XFEL) pulses, where the ≦35 fs duration of exposure of an individual crystal yields diffraction data before photoreduction-induced structural changes can manifest. Merging diffraction patterns obtained from thousands of crystals generates radiation damage free, 1.95 Å resolution crystal structures for the fully oxidized and fully reduced states of the sMMOH:MMOB complex for the first time. The results provide new insight into the manner by which the diiron cluster and the active site environment are reorganized by the regulatory protein component in order to enhance the steps of oxygen activation and methane oxidation. This study also emphasizes the value of XFEL and serial femtosecond crystallography (SFX) methods for investigating the structures of metalloenzymes with radiation sensitive metal active sites.	Jul 2020
	Untangling the sequence of events during the S 2 → S 3 transition in photosystem II and implications for the water oxidation mechanism Mohamed Ibrahim , Thomas Fransson , Ruchira Chatterjee , Mun Hon Cheah , Rana Hussein , Louise Lassalle , Kyle D. Sutherlin , Iris D. Young , Franklin D. Fuller , Sheraz Gul , In-Sik Kim , Philipp S. Simon , Casper De Lichtenberg , Petko Chernev , Isabel Bogacz , Cindy C. Pham , Allen M. Orville , Nicholas Saichek , Trent Northen , Alexander Batyuk , Sergio Carbajo , Roberto Alonso-Mori , Kensuke Tono , Shigeki Owada , Asmit Bhowmick , Robert Bolotovsky , Derek Mendez , Nigel W. Moriarty , James M. Holton , Holger Dobbek , Aaron S. Brewster , Paul D. Adams , Nicholas K. Sauter , Uwe Bergmann , Athina Zouni , Johannes Messinger , Jan Kern , Vittal K. Yachandra , Junko Yano Proceedings Of The National Academy Of Sciences 766 DOI: 10.1073/pnas.2000529117 Open Access Show Abstract ▼ Abstract: In oxygenic photosynthesis, light-driven oxidation of water to molecular oxygen is carried out by the oxygen-evolving complex (OEC) in photosystem II (PS II). Recently, we reported the room-temperature structures of PS II in the four (semi)stable S-states, S1, S2, S3, and S0, showing that a water molecule is inserted during the S2 → S3 transition, as a new bridging O(H)-ligand between Mn1 and Ca. To understand the sequence of events leading to the formation of this last stable intermediate state before O2 formation, we recorded diffraction and Mn X-ray emission spectroscopy (XES) data at several time points during the S2 → S3 transition. At the electron acceptor site, changes due to the two-electron redox chemistry at the quinones, QA and QB, are observed. At the donor site, tyrosine YZ and His190 H-bonded to it move by 50 µs after the second flash, and Glu189 moves away from Ca. This is followed by Mn1 and Mn4 moving apart, and the insertion of OX(H) at the open coordination site of Mn1. This water, possibly a ligand of Ca, could be supplied via a “water wheel”-like arrangement of five waters next to the OEC that is connected by a large channel to the bulk solvent. XES spectra show that Mn oxidation (τ of ∼350 µs) during the S2 → S3 transition mirrors the appearance of OX electron density. This indicates that the oxidation state change and the insertion of water as a bridging atom between Mn1 and Ca are highly correlated.	May 2020
I03-Macromolecular Crystallography I04-Macromolecular Crystallography	Lead optimization of phthalazinone phosphodiesterase inhibitors as novel antitrypanosomal compounds Irene G. Salado , Abhimanyu Singh , Carlos Moreno-Cinos , Guna Sakaine , Marco Siderius , Pieter Van Der Veken , An Matheeussen , Tiffany Van Der Meer , Payman Sadek , Sheraz Gul , Louis Maes , Geert Jan Sterk , Rob Leurs , David Brown , Koen Augustyns Journal Of Medicinal Chemistry DOI: 10.1021/acs.jmedchem.9b00985 Diamond Proposal Number(s): [16207, 15075] Show Abstract ▼ Abstract: Human African trypanosomiasis is causing thousands of deaths every year in the rural areas of Africa. In this manuscript we describe the optimization of a family of phtalazinone derivatives. Phosphodiesterases have emerged as attractive molecular targets for a novel treatment for a variety of neglected parasitic diseases. Compound 1 resulted to be a potent TbrPDEB1 inhibitor with interesting activity against T. brucei in a phenotypic screen. Derivative 1 was studied in an acute in vivo mouse disease model but unfortunately showed no efficacy due to low metabolic stability. We report structural modifications to achieve compounds with an improved metabolic stability while maintaining high potency against TbrPDEB1 and T. brucei. Compound 14, presented a good microsomal stability in mouse and human microsomes and provides a good starting point for future efforts.	Mar 2020
I24-Microfocus Macromolecular Crystallography	Photoreversible interconversion of a phytochrome photosensory module in the crystalline state E. Sethe Burgie , Jonathan A. Clinger , Mitchell D. Miller , Aaron S. Brewster , Pierre Aller , Agata Butryn , Franklin D. Fuller , Sheraz Gul , Iris D. Young , Cindy C. Pham , In-Sik Kim , Asmit Bhowmick , Lee J. O’riordan , Kyle D. Sutherlin , Joshua V. Heinemann , Alexander Batyuk , Roberto Alonso-Mori , Mark S. Hunter , Jason E. Koglin , Junko Yano , Vittal K. Yachandra , Nicholas K. Sauter , Aina E. Cohen , Jan Kern , Allen M. Orville , George N. Phillips , Richard D. Vierstra Proceedings Of The National Academy Of Sciences 37 DOI: 10.1073/pnas.1912041116 Diamond Proposal Number(s): [19458] Open Access Show Abstract ▼ Abstract: A major barrier to defining the structural intermediates that arise during the reversible photointerconversion of phytochromes between their biologically inactive and active states has been the lack of crystals that faithfully undergo this transition within the crystal lattice. Here, we describe a crystalline form of the cyclic GMP phosphodiesterases/adenylyl cyclase/FhlA (GAF) domain from the cyanobacteriochrome PixJ in Thermosynechococcus elongatus assembled with phycocyanobilin that permits reversible photoconversion between the blue light-absorbing Pb and green light-absorbing Pg states, as well as thermal reversion of Pg back to Pb. The X-ray crystallographic structure of Pb matches previous models, including autocatalytic conversion of phycocyanobilin to phycoviolobilin upon binding and its tandem thioether linkage to the GAF domain. Cryocrystallography at 150 K, which compared diffraction data from a single crystal as Pb or after irradiation with blue light, detected photoconversion product(s) based on Fobs − Fobs difference maps that were consistent with rotation of the bonds connecting pyrrole rings C and D. Further spectroscopic analyses showed that phycoviolobilin is susceptible to X-ray radiation damage, especially as Pg, during single-crystal X-ray diffraction analyses, which could complicate fine mapping of the various intermediate states. Fortunately, we found that PixJ crystals are amenable to serial femtosecond crystallography (SFX) analyses using X-ray free-electron lasers (XFELs). As proof of principle, we solved by room temperature SFX the GAF domain structure of Pb to 1.55-Å resolution, which was strongly congruent with synchrotron-based models. Analysis of these crystals by SFX should now enable structural characterization of the early events that drive phytochrome photoconversion.	Dec 2019
I02-Macromolecular Crystallography	Structural insights into the development of cycloguanil derivatives as Trypanosoma brucei pteridine reductase 1 inhibitors Giacomo Landi , Pasquale Linciano , Chiara Borsari , Claudia P. Bertolacini , Carolina Borsoi Moraes , Anabela Cordeiro-Da-Silva , Sheraz Gul , Gesa Witt , Maria Kuzikov , Maria Paola Costi , Cecilia Pozzi , Stefano Mangani Acs Infectious Diseases DOI: 10.1021/acsinfecdis.8b00358 Diamond Proposal Number(s): [11690] Show Abstract ▼ Abstract: Cycloguanil is a known dihydrofolate reductase (DHFR) inhibitor, but there is no evidence of its activity on pteridine reductase (PTR), the main metabolic bypass to DHFR inhibition in trypanosomatid parasites. Here, we provide experimental evidence of cycloguanil as an inhibitor of Trypanosoma brucei PTR1 (TbPTR1). A small library of cycloguanil derivatives was develop, resulting in 1 and 2a having IC50 of 692 and 186 nM, respectively, towards TbPTR1. Structural analysis revealed that the increased potency of 1 and 2a is due to the combined contributions of hydrophobic interactions, H-bonds and halogen bonds. Moreover, in vitro cell growth inhibition tests indicated that 2a is also effective on T. brucei. The simultaneous inhibition of DHFR and PTR1 activity in T. brucei is a new promising strategy for the treatment of human African Trypanosomiasis. On this purpose, 1,6-dihydrotriazines represent new molecular tools to develop potent dual PTR and DHFR inhibitors.	Apr 2019
I04-1-Macromolecular Crystallography (fixed wavelength) I04-Macromolecular Crystallography	Enhancement of benzothiazoles as Pteridine Reductase-1 (PTR1) inhibitors for the treatment of Trypanosomatidic infections Pasquale Linciano , Cecilia Pozzi , Lucia Dello Iacono , Flavio Di Pisa , Giacomo Landi , Alessio Bonucci , Sheraz Gul , Maria Kuzikov , Bernhard Ellinger , Gesa Witt , Nuno Santarem , Catarina Baptista , Caio Franco , Carolina Borsoi Moraes , Wolfgang Müller , Ulrike Wittig , Rosaria Luciani , Antony Sesenna , Antonio Quotadamo , Stefania Ferrari , Ina Pöhner , Anabela Cordeiro-Da-Silva , Stefano Mangani , Luca Costantino , Maria Paola Costi Journal Of Medicinal Chemistry DOI: 10.1021/acs.jmedchem.8b02021 Diamond Proposal Number(s): [11690, 15832] Show Abstract ▼ Abstract: 2-amino-benzo[d]thiazole has been identified as new core moiety for the development of improved PTR1 inhibitors and anti-Trypanosomatidic agents. Through a molecular docking approach and the crystal structure of 6-(methylsulfonyl)benzo[d]thiazol-2-amine ternary complex with TbPTR1, 42 new compounds were designed, synthesized and evaluated for their ability to inhibit T. brucei and L. major PTR1 enzymes and in-vitro activity against Trypanosoma brucei and amastigote stage of Leishmania infantum. We identified several 2-amino-benzo[d]thiazole derivatives with improved activity against the enzymes (TbPTR1 IC50 = 0.35 µM; LmPTR1 IC50 = 1.9 µM) and anti-parasitic activity against T. brucei in the low µM range. Ten compounds, with low/sub micromolar inhibitor activity against TbPTR1, were able to potentiate the antiparasitic activity of methotrexate (MTX) when evaluated in combination against T. brucei, with a Potentiating Index (PI) ranging between 1.2 and 2.7. The compound library was profile for an early ADME-Toxicity profile and the compounds showing the best in vitro/enzymatic inhibition properties were selected for progression. 2-amino-N-benzylbenzo[d]thiazole-6-carboxamide (4c), was finally identified as a novel potent and selective anti-trypanocydal agent (EC50 = 7.0 µM) with an overall safe early ADME-Toxicity profile. The pharmacokinetic studies of 4c in BALB/c mice using a hydroxypropyl-β-cyclodextrin formulation yielded good oral bioavailability, confirming its suitability for progression to in-vivo anti-parasitic studies.	Mar 2019

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