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Instruments / Technical Area	Publication Details	Published
I24-Microfocus Macromolecular Crystallography	Galectin-8N-selective 4-halophenylphthalazinone-galactals double π-stack in a unique pocket Sjors Van Klaveren , Mujtaba Hassan , Maria Håkansson , Richard E. Johnsson , Jessica Larsson , Žiga Jakopin , Marko Anderluh , Hakon Leffler , Tihomir Tomašič , Ulf J. Nilsson Acs Medicinal Chemistry Letters 15, 1319 - 1324 DOI: 10.1021/acsmedchemlett.4c00212 Open Access Show Abstract ▼ Abstract: Galectin-8 contains two different carbohydrate recognition domains (CRDs). Selective inhibitors for at least one CRD are desirable for galectin-8 biology studies and potentially for pharmacological purposes. Structure-guided design led to the discovery of potent and selective glycomimetic–heterocycle hybrid ligands, with a 4-(p-bromophenyl)phthalazinone derivative displaying a 34 μM Kd for galectin-8N (N-terminal CRD), no binding to galectin-8C (C-terminal CRD), -1, -3, -4N, -7, -9C, or -9N, and >40-fold selectivity over galectin-4C. Selectivity was achieved with the halogenated 4-phenylphthalazinone moiety occupying a galectin-8N-specific sub-pocket. A 1.30 Å resolution X-ray structure revealed the phthalazinone moiety stacking with Arg45 and the 4-bromophenyl moiety stacking both Arg59 and Tyr141 of galectin-8N. Physicochemical and in vitro ADME studies revealed a desirable LogD, which also translated to good passive permeability. The chemical, microsome, and plasma stability support these compounds as promising tool compounds and candidates for hit-to-lead optimization.	Aug 2024
I04-Macromolecular Crystallography	Exploring the interaction of N-(benzothiazol-2-yl)pyrrolamide DNA gyrase inhibitors with the GyrB ATP-binding site lipophilic floor: A medicinal chemistry and QTAIM study Nace Zidar , Andrej Emanuel Cotman , Wessel Sinnige , Ondrej Benek , Michaela Barančokova , Anamarija Zega , Lucija Peterlin Mašič , Tihomir Tomašič , Janez Ilaš , Sara R. Henderson , Julia E. A. Mundy , Anthony Maxwell , Clare E. M. Stevenson , David M. Lawson , Geert Jan Sterk , Rodrigo Tosso , Lucas Gutierrez , Ricardo D. Enriz , Danijel Kikelj Bioorganic & Medicinal Chemistry 43 DOI: 10.1016/j.bmc.2024.117798 Diamond Proposal Number(s): [18565] Open Access Show Abstract ▼ Abstract: N-(Benzothiazole-2-yl)pyrrolamide DNA gyrase inhibitors with benzyl or phenethyl substituents attached to position 3 of the benzothiazole ring or to the carboxamide nitrogen atom were prepared and studied for their inhibition of Escherichia coli DNA gyrase by supercoiling assay. Compared to inhibitors bearing the substituents at position 4 of the benzothiazole ring, the inhibition was attenuated by moving the substituent to position 3 and further to the carboxamide nitrogen atom. A co-crystal structure of (Z)-3-benzyl-2-((4,5-dibromo-1H-pyrrole-2-carbonyl)imino)-2,3-dihydrobenzo[d]-thiazole-6-carboxylic acid (I) in complex with E. coli GyrB24 (ATPase subdomain) was solved, revealing the binding mode of this type of inhibitor to the ATP-binding pocket of the E. coli GyrB subunit. The key binding interactions were identified and their contribution to binding was rationalised by quantum theory of atoms in molecules (QTAIM) analysis. Our study shows that the benzyl or phenethyl substituents bound to the benzothiazole core interact with the lipophilic floor of the active site, which consists mainly of residues Gly101, Gly102, Lys103 and Ser108. Compounds with substituents at position 3 of the benzothiazole core were up to two orders of magnitude more effective than compounds with substituents at the carboxamide nitrogen. In addition, the 6-oxalylamino compounds were more potent inhibitors of E. coli DNA gyrase than the corresponding 6-acetamido analogues.	Jun 2024
I03-Macromolecular Crystallography	Exploring the 5-substituted 2-aminobenzothiazole-based DNA Gyrase B inhibitors active against ESKAPE pathogens Maša Sterle , Martina Durcik , Clare E. M. Stevenson , Sara Henderson , Petra Eva Szili , Marton Czikkely , David M. Lawson , Anthony Maxwell , Dominique Cahard , Danijel Kikelj , Nace Zidar , Csaba Pal , Lucija Peterlin Mašič , Janez Ilaš , Tihomir Tomašič , Andrej Emanuel Cotman , Anamarija Zega Acs Omega DOI: 10.1021/acsomega.3c01930 Diamond Proposal Number(s): [18565] Open Access Show Abstract ▼ Abstract: We present a new series of 2-aminobenzothiazole-based DNA gyrase B inhibitors with promising activity against ESKAPE bacterial pathogens. Based on the binding information extracted from the cocrystal structure of DNA gyrase B inhibitor A, in complex with Escherichia coli GyrB24, we expanded the chemical space of the benzothiazole-based series to the C5 position of the benzothiazole ring. In particular, compound E showed low nanomolar inhibition of DNA gyrase (IC50 < 10 nM) and broad-spectrum antibacterial activity against pathogens belonging to the ESKAPE group, with the minimum inhibitory concentration < 0.03 μg/mL for most Gram-positive strains and 4–16 μg/mL against Gram-negative E. coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. To understand the binding mode of the synthesized inhibitors, a combination of docking calculations, molecular dynamics (MD) simulations, and MD-derived structure-based pharmacophore modeling was performed. The computational analysis has revealed that the substitution at position C5 can be used to modify the physicochemical properties and antibacterial spectrum and enhance the inhibitory potency of the compounds. Additionally, a discussion of challenges associated with the synthesis of 5-substituted 2-aminobenzothiazoles is presented.	Jun 2023
I04-Macromolecular Crystallography	New dual inhibitors of bacterial topoisomerases with broad-spectrum antibacterial activity and in vivo efficacy against vancomycin-intermediate Staphylococcus aureus Martina Durcik , Andrej Emanuel Cotman , Žan Toplak , Štefan Možina , Žiga Skok , Petra Eva Szili , Márton Czikkely , Elvin Maharramov , Thu Hien Vu , Maria Vittoria Piras , Nace Zidar , Janez Ilaš , Anamarija Zega , Jurij Trontelj , Luis A. Pardo , Diarmaid Hughes , Douglas Huseby , Tália Berruga-Fernández , Sha Cao , Ivailo Simoff , Richard Svensson , Sergiy V. Korol , Zhe Jin , Francisca Vicente , Maria C. Ramos , Julia E. A. Mundy , Anthony Maxwell , Clare E. M. Stevenson , David M. Lawson , Björn Glinghammar , Eva Sjöström , Martin Bohlin , Joanna Oreskär , Sofie Alvér , Guido V. Janssen , Geert Jan Sterk , Danijel Kikelj , Csaba Pal , Tihomir Tomašič , Lucija Peterlin Mašič Journal Of Medicinal Chemistry 1703 DOI: 10.1021/acs.jmedchem.2c01905 Diamond Proposal Number(s): [25108] Open Access Show Abstract ▼ Abstract: A new series of dual low nanomolar benzothiazole inhibitors of bacterial DNA gyrase and topoisomerase IV were developed. The resulting compounds show excellent broad-spectrum antibacterial activities against Gram-positive Enterococcus faecalis, Enterococcus faecium and multidrug resistant (MDR) Staphylococcus aureus strains [best compound minimal inhibitory concentrations (MICs): range, <0.03125–0.25 μg/mL] and against the Gram-negatives Acinetobacter baumannii and Klebsiella pneumoniae (best compound MICs: range, 1–4 μg/mL). Lead compound 7a was identified with favorable solubility and plasma protein binding, good metabolic stability, selectivity for bacterial topoisomerases, and no toxicity issues. The crystal structure of 7a in complex with Pseudomonas aeruginosa GyrB24 revealed its binding mode at the ATP-binding site. Expanded profiling of 7a and 7h showed potent antibacterial activity against over 100 MDR and non-MDR strains of A. baumannii and several other Gram-positive and Gram-negative strains. Ultimately, in vivo efficacy of 7a in a mouse model of vancomycin-intermediate S. aureus thigh infection was also demonstrated.	Mar 2023
I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength) I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Discovery and hit-to-lead optimization of benzothiazole scaffold-based DNA gyrase inhibitors with potent activity against Acinetobacter baumannii and Pseudomonas aeruginosa Andrej Emanuel Cotman , Martina Durcik , Davide Benedetto Tiz , Federica Fulgheri , Daniela Secci , Maša Sterle , Štefan Možina , Žiga Skok , Nace Zidar , Anamarija Zega , Janez Ilaš , Lucija Peterlin Mašič , Tihomir Tomašič , Diarmaid Hughes , Douglas L. Huseby , Sha Cao , Linnéa Garoff , Talía Berruga Fernández , Paraskevi Giachou , Lisa Crone , Ivailo Simoff , Richard Svensson , Bryndis Birnir , Sergiy V. Korol , Zhe Jin , Francisca Vicente , Maria C. Ramos , Mercedes De La Cruz , Björn Glinghammar , Lena Lenhammar , Sara R. Henderson , Julia E. A. Mundy , Anthony Maxwell , Claren E. M. Stevenson , David M. Lawson , Guido V. Janssen , Geert Jan Sterk , Danijel Kikelj Journal Of Medicinal Chemistry DOI: 10.1021/acs.jmedchem.2c01597 Diamond Proposal Number(s): [18565, 25108] Open Access Show Abstract ▼ Abstract: We have developed compounds with a promising activity against Acinetobacter baumannii and Pseudomonas aeruginosa, which are both on the WHO priority list of antibiotic-resistant bacteria. Starting from DNA gyrase inhibitor 1, we identified compound 27, featuring a 10-fold improved aqueous solubility, a 10-fold improved inhibition of topoisomerase IV from A. baumannii and P. aeruginosa, a 10-fold decreased inhibition of human topoisomerase IIα, and no cross-resistance to novobiocin. Cocrystal structures of 1 in complex with Escherichia coli GyrB24 and (S)-27 in complex with A. baumannii GyrB23 and P. aeruginosa GyrB24 revealed their binding to the ATP-binding pocket of the GyrB subunit. In further optimization steps, solubility, plasma free fraction, and other ADME properties of 27 were improved by fine-tuning of lipophilicity. In particular, analogs of 27 with retained anti-Gram-negative activity and improved plasma free fraction were identified. The series was found to be nongenotoxic, nonmutagenic, devoid of mitochondrial toxicity, and possessed no ion channel liabilities.	Jan 2023
I03-Macromolecular Crystallography	Structure-guided design of D-galactal derivatives with high affinity and selectivity for the galectin-8 N-terminal domain Mujtaba Hassan , Floriane Baussière , Samo Guzelj , Anders P. Sundin , Maria Håkansson , Rebeka Kovačič , Hakon Leffler , Tihomir Tomašič , Marko Anderluh , Žiga Jakopin , Ulf J. Nilsson Acs Medicinal Chemistry Letters 12, 1745 - 1752 DOI: 10.1021/acsmedchemlett.1c00371 Diamond Proposal Number(s): [15916] Open Access Show Abstract ▼ Abstract: Galectin-8 is a carbohydrate-binding protein that plays a crucial role in tumor progression and metastasis, antibacterial autophagy, modulation of the immune system, and bone remodeling. The design, synthesis, and protein affinity evaluation of a set of C-3 substituted benzimidazole and quinoline d-galactal derivatives identified a d-galactal-benzimidazole hybrid as a selective ligand for the galectin-8 N-terminal domain (galectin-8N), with a Kd of 48 μM and 15-fold selectivity over galectin-3 and even better selectivity over the other mammalian galectins. X-ray structural analysis of galectin-8N in complex with one benzimidazole- and one quinoline-galactal derivative at 1.52 and 2.1 Å together with molecular dynamics simulations and quantum mechanical calculations of galectin-8N in complex with the benzimidazole derivative revealed orbital overlap between a NH LUMO of Arg45 with electron rich HOMOs of the olefin and O4 of the d-galactal. Such overlap is hypothesized to contribute to the high affinity of the d-galactal-derived ligands for galectin-8N. A (3-(4,5-dimethylthiazol-2-yl)-5-(3- carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay evaluation of the d-galactal-benzimidazole hybrid and an analogous galactoside derivative on a panel of cell lines with MTS assay showed no effect on cell viability up to 100 μM concentration. A subsequent functional assay using the MDA-MB-231 cell line demonstrated that the d-galactal-benzimidazole hybrid and the analogous galactoside derivative reduced the secretion of the proinflammatory cytokines interleukin-6 (IL-6) and IL-8 in a dose-dependent manner. Therefore, these compounds represent potential probes for galectin-8N pharmacology investigations and possibly promising leads for the design and synthesis of potent and selective galectin-8 inhibitors as potential antitumor and anti-inflammatory agents.	Nov 2021
I04-Macromolecular Crystallography	Benzimidazole–galactosides bind selectively to the Galectin-8 N-Terminal domain: Structure-based design and optimisation Mujtaba Hassan , Sjors Van Klaveren , Maria Håkansson , Carl Diehl , Rebeka Kovačič , Floriane Baussière , Anders Sundin , Jaka Dernovšek , Björn Walse , Fredrik Zetterberg , Hakon Leffler , Marko Anderluh , Tihomir Tomašič , Žiga Jakopin , Ulf J. Nilsson European Journal Of Medicinal Chemistry 19 DOI: 10.1016/j.ejmech.2021.113664 Diamond Proposal Number(s): [23282] Open Access Show Abstract ▼ Abstract: We have obtained the X-ray crystal structure of the galectin-8 N-terminal domain (galectin-8N) with a previously reported quinoline–galactoside ligand at a resolution of 1.6 Å. Based on this X-ray structure, a collection of galactosides derivatised at O3 with triazole, benzimidazole, benzothiazole, and benzoxazole moieties were designed and synthesised. This led to the discovery of a 3-O-(N-methylbenzimidazolylmethyl)–galactoside with a Kd of 1.8 μM for galectin-8N, the most potent selective synthetic galectin-8N ligand to date. Molecular dynamics simulations showed that benzimidazole–galactoside derivatives bind the non-conserved amino acid Gln47, accounting for the higher selectivity for galectin-8N. Galectin-8 is a carbohydrate-binding protein that plays a key role in pathological lymphangiogenesis, modulation of the immune system, and autophagy. Thus, the benzimidazole-derivatised galactosides represent promising compounds for studies of the pathological implications of galectin-8, as well as a starting point for the development of anti-tumour and anti-inflammatory therapeutics targeting galectin-8.	Jun 2021
I04-Macromolecular Crystallography	New dual ATP-competitive inhibitors of bacterial DNA gyrase and topoisomerase IV active against ESKAPE pathogens Martina Durcik , Ákos Nyerges , Žiga Skok , Darja Gramec Skledar , Jurij Trontelj , Nace Zidar , Janez Ilaš , Anamarija Zega , Cristina D. Cruz , Päivi Tammela , Martin Welin , Yengo R. Kimbung , Dorota Focht , Ondřej Benek , Tamás Révész , Gábor Draskovits , Petra Éva Szili , Lejla Daruka , Csaba Pál , Danijel Kikelj , Lucija Peterlin Mašič , Tihomir Tomašič European Journal Of Medicinal Chemistry 213 DOI: 10.1016/j.ejmech.2021.113200 Diamond Proposal Number(s): [20028] Show Abstract ▼ Abstract: The rise in multidrug-resistant bacteria defines the need for identification of new antibacterial agents that are less prone to resistance acquisition. Compounds that simultaneously inhibit multiple bacterial targets are more likely to suppress the evolution of target-based resistance than monotargeting compounds. The structurally similar ATP binding sites of DNA gyrase and topoisomerase Ⅳ offer an opportunity to accomplish this goal. Here we present the design and structure-activity relationship analysis of balanced, low nanomolar inhibitors of bacterial DNA gyrase and topoisomerase IV that show potent antibacterial activities against the ESKAPE pathogens. For inhibitor 31c, a crystal structure in complex with Staphylococcus aureus DNA gyrase B was obtained that confirms the mode of action of these compounds. The best inhibitor, 31h, does not show any in vitro cytotoxicity and has excellent potency against Gram-positive (MICs: range, 0.0078–0.0625 μg/mL) and Gram-negative pathogens (MICs: range, 1–2 μg/mL). Furthermore, 31h inhibits GyrB mutants that can develop resistance to other drugs. Based on these data, we expect that structural derivatives of 31h will represent a step toward clinically efficacious multitargeting antimicrobials that are not impacted by existing antimicrobial resistance.	Mar 2021
I04-Macromolecular Crystallography	Exploring the chemical space of benzothiazole-based DNA gyrase B inhibitors Žiga Skok , Michaela Barančoková , Ondřej Benek , Cristina Durante Cruz , Päivi Tammela , Tihomir Tomašič , Nace Zidar , Lucija Peterlin Mašič , Anamarija Zega , Clare E. M. Stevenson , Julia E. A. Mundy , David M. Lawson , Anthony Maxwell , Danijel Kikelj , Janez Ilaš Acs Medicinal Chemistry Letters DOI: 10.1021/acsmedchemlett.0c00416 Diamond Proposal Number(s): [18565] Open Access Show Abstract ▼ Abstract: We designed and synthesized a series of inhibitors of the bacterial enzymes DNA gyrase and DNA topoisomerase IV, based on our recently published benzothiazole-based inhibitor bearing an oxalyl moiety. To improve the antibacterial activity and retain potent enzymatic activity, we systematically explored the chemical space. Several strategies of modification were followed: varying substituents on the pyrrole carboxamide moiety, alteration of the central scaffold, including variation of substitution position and, most importantly, modification of the oxalyl moiety. Compounds with acidic, basic, and neutral properties were synthesized. To understand the mechanism of action and binding mode, we have obtained a crystal structure of compound 16a, bearing a primary amino group, in complex with the N-terminal domain of E. coli gyrase B (24 kDa) (PDB: 6YD9). Compound 15a, with a low molecular weight of 383 Da, potent inhibitory activity on E. coli gyrase (IC50 = 9.5 nM), potent antibacterial activity on E. faecalis (MIC = 3.13 μM), and efflux impaired E. coli strain (MIC = 0.78 μM), is an important contribution for the development of novel gyrase and topoisomerase IV inhibitors in Gram-negative bacteria.	Oct 2020

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