1
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Shi G, Shaw GX, Ji X. Bisubstrate inhibitors of 6-hydroxymethyl-7,8-dihydroptein pyrophosphokinase: Toward cell permeability. Bioorg Med Chem Lett 2024; 113:129977. [PMID: 39332646 DOI: 10.1016/j.bmcl.2024.129977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 08/13/2024] [Accepted: 09/23/2024] [Indexed: 09/29/2024]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a key enzyme in the folate biosynthesis pathway. It catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP). HPPK is essential for microorganisms but is absent in mammals. Yet, it is not the target of any existing antibiotics. Hence, this enzyme is an attractive target for developing novel antimicrobial agents. A wealth of structural and mechanistic information has provided solid basis for structure-based design of HPPK inhibitors. Our bisubstrate inhibitors were initially created by linking 6-hydroxymethylpterin to adenosine through 2, 3, or 4 phosphate groups (HPnA, n = 2, 3, or 4), among which HP4A exhibited the highest binding affinity (Kd = 0.47 ± 0.04 μM). Further development was carried out based on high-resolution structures of HPPK in complex with HP4A. Replacing the phosphate bridge with a piperidine linked thioether eliminated multiple negative charges of the bridge. Substituting the pterin moiety with 7,7-dimethyl-7,8-dihydropterin improved the binding affinity. Arming the piperidine ring with a carboxyl group and oxidizing the thioether further enhanced the potency, resulting in a druglike inhibitor of HPPK (Kd = 0.047 ± 0.007 μM). None of these inhibitors, however, exhibits bacterial cell permeability. It is most likely due to the lack of active folate transporters in bacteria. Replacing the pterin moiety with a 7-deazagaunine moiety, we have obtained a novel bisubstrate inhibitor (HP-101) showing observable cell permeability toward a Gram-positive bacterium. Here, we report the in vitro activity of HP-101 and its structure in complex with HPPK, providing a framework for structure-based further development.
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Affiliation(s)
- Genbin Shi
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA.
| | - Gary X Shaw
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA; Current Address: Thoracic and Gastrointestinal Malignancies Branch, National Cancer Institute, Bethesda, MD 20892, USA.
| | - Xinhua Ji
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA
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2
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Vadlamani G, Sukhoverkov KV, Haywood J, Breese KJ, Fisher MF, Stubbs KA, Bond CS, Mylne JS. Crystal structure of Arabidopsis thaliana HPPK/DHPS, a bifunctional enzyme and target of the herbicide asulam. PLANT COMMUNICATIONS 2022; 3:100322. [PMID: 35605193 PMCID: PMC9284294 DOI: 10.1016/j.xplc.2022.100322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/21/2022] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
Herbicides are vital for modern agriculture, but their utility is threatened by genetic or metabolic resistance in weeds, as well as regulatory barriers. Of the known herbicide modes of action, 7,8-dihydropterin synthase (DHPS), which is involved in folate biosynthesis, is targeted by just one commercial herbicide, asulam. A mimic of the substrate para-aminobenzoic acid, asulam is chemically similar to sulfonamide antibiotics, and although it is still in widespread use, asulam has faced regulatory scrutiny. With an entire mode of action represented by just one commercial agrochemical, we sought to improve the understanding of its plant target. Here we solve a 2.3 Å resolution crystal structure for Arabidopsis thaliana DHPS that is conjoined to 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), and we reveal a strong structural conservation with bacterial counterparts at the sulfonamide-binding pocket of DHPS. We demonstrate that asulam and the antibiotic sulfamethoxazole have herbicidal as well as antibacterial activity, and we explore the structural basis of their potency by modeling these compounds in mitochondrial HPPK/DHPS. Our findings suggest limited opportunity for the rational design of plant selectivity from asulam and indicate that pharmacokinetic or delivery differences between plants and microbes might be the best ways to safeguard this mode of action.
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Affiliation(s)
- Grishma Vadlamani
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Kirill V Sukhoverkov
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Joel Haywood
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Karen J Breese
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Mark F Fisher
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Keith A Stubbs
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Charles S Bond
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Joshua S Mylne
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia.
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3
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Müller R, Gerwel TM, Kimuda MP, Bishop ÖT, Veale CGL, Hoppe HC. Virtual screening and in vitro validation identifies the first reported inhibitors of Salmonella enterica HPPK. RSC Med Chem 2021; 12:1750-1756. [PMID: 34778775 PMCID: PMC8528203 DOI: 10.1039/d1md00237f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/23/2021] [Indexed: 11/21/2022] Open
Abstract
HPPK, which directly precedes DHPS in the folate biosynthetic pathway, is a promising but chronically under-exploited anti-microbial target. Here we report the identification of new S. enterica HPPK inhibitors, offering potential for new resistance circumventing S. enterica therapies as well as avenues for diversifying the current HPPK inhibitor space.
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Affiliation(s)
- Ronel Müller
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal Private Bag X01 Scottsville 3209 South Africa
| | - Tiaan M Gerwel
- Faculty of Pharmacy, Rhodes University Makhanda 6140 South Africa
| | - Magambo Phillip Kimuda
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University Makhanda 6140 South Africa
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University Makhanda 6140 South Africa
| | - Clinton G L Veale
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal Private Bag X01 Scottsville 3209 South Africa
| | - Heinrich C Hoppe
- Department of Biochemistry and Microbiology, Rhodes University Makhanda 6140 South Africa
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4
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Shi G, Shaw GX, Zhu F, Tarasov SG, Ji X. Bisubstrate inhibitors of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: Transition state analogs for high affinity binding. Bioorg Med Chem 2021; 29:115847. [PMID: 33199204 PMCID: PMC7855645 DOI: 10.1016/j.bmc.2020.115847] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/20/2020] [Accepted: 11/02/2020] [Indexed: 11/22/2022]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a key enzyme in the folate biosynthesis pathway. It catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP). HPPK is essential for microorganisms but absent in mammals; therefore, it is an attractive target for developing novel antimicrobial agents. Previously, based on our studies of the structure and mechanism of HPPK, we created first-generation bisubstrate inhibitors by linking 6-hydroxymethylpterin to adenosine through phosphate groups, and developed second-generation inhibitors by replacing the phosphate bridge with a linkage that contains a piperidine moiety. Here, we report third-generation inhibitors designed based on the piperidine-containing inhibitor, mimicking the transition state. We synthesized two such inhibitors, characterized their protein-binding and enzyme inhibition properties, and determined their crystal structures in complex with HPPK, advancing the development of such bisubstrate analog inhibitors.
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Affiliation(s)
- Genbin Shi
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Gary X Shaw
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Fengxia Zhu
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA; School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huaiyin, Jiangsu Province, China(1)
| | - Sergey G Tarasov
- Structural Biophysics Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA.
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5
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Yogavel M, Nettleship JE, Sharma A, Harlos K, Jamwal A, Chaturvedi R, Sharma M, Jain V, Chhibber-Goel J, Sharma A. Structure of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase-dihydropteroate synthase from Plasmodium vivax sheds light on drug resistance. J Biol Chem 2018; 293:14962-14972. [PMID: 30104413 DOI: 10.1074/jbc.ra118.004558] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/08/2018] [Indexed: 11/06/2022] Open
Abstract
The genomes of the malaria-causing Plasmodium parasites encode a protein fused of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS) domains that catalyze sequential reactions in the folate biosynthetic pathway. Whereas higher organisms derive folate from their diet and lack the enzymes for its synthesis, most eubacteria and a number of lower eukaryotes including malaria parasites synthesize tetrahydrofolate via DHPS. Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) HPPK-DHPSs are currently targets of drugs like sulfadoxine (SDX). The SDX effectiveness as an antimalarial drug is increasingly diminished by the rise and spread of drug-resistant mutations. Here, we present the crystal structure of PvHPPK-DHPS in complex with four substrates/analogs, revealing the bifunctional PvHPPK-DHPS architecture in an unprecedented state of enzymatic activation. SDX's effect on HPPK-DHPS is due to 4-amino benzoic acid (pABA) mimicry, and the PvHPPK-DHPS structure sheds light on the SDX-binding cavity, as well as on mutations that effect SDX potency. We mapped five dominant drug resistance mutations in PvHPPK-DHPS: S382A, A383G, K512E/D, A553G, and V585A, most of which occur individually or in clusters proximal to the pABA-binding site. We found that these resistance mutations subtly alter the intricate enzyme/pABA/SDX interactions such that DHPS affinity for pABA is diminished only moderately, but its affinity for SDX is changed substantially. In conclusion, the PvHPPK-DHPS structure rationalizes and unravels the structural bases for SDX resistance mutations and highlights architectural features in HPPK-DHPSs from malaria parasites that can form the basis for developing next-generation anti-folate agents to combat malaria parasites.
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Affiliation(s)
- Manickam Yogavel
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India,
| | - Joanne E Nettleship
- the Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom, and.,the Oxford Protein Production Facility, United Kingdom Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford OX11 0FA, United Kingdom
| | - Akansha Sharma
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Karl Harlos
- the Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom, and
| | - Abhishek Jamwal
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Rini Chaturvedi
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Manmohan Sharma
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Vitul Jain
- the Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom, and
| | - Jyoti Chhibber-Goel
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Amit Sharma
- From the Molecular Medicine-Structural Parasitology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
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6
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Griffith EC, Wallace MJ, Wu Y, Kumar G, Gajewski S, Jackson P, Phelps GA, Zheng Z, Rock CO, Lee RE, White SW. The Structural and Functional Basis for Recurring Sulfa Drug Resistance Mutations in Staphylococcus aureus Dihydropteroate Synthase. Front Microbiol 2018; 9:1369. [PMID: 30065703 PMCID: PMC6057106 DOI: 10.3389/fmicb.2018.01369] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/06/2018] [Indexed: 11/13/2022] Open
Abstract
Staphylococcal species are a leading cause of bacterial drug-resistant infections and associated mortality. One strategy to combat bacterial drug resistance is to revisit compromised targets, and to circumvent resistance mechanisms using structure-assisted drug discovery. The folate pathway is an ideal candidate for this approach. Antifolates target an essential metabolic pathway, and the necessary detailed structural information is now available for most enzymes in this pathway. Dihydropteroate synthase (DHPS) is the target of the sulfonamide class of drugs, and its well characterized mechanism facilitates detailed analyses of how drug resistance has evolved. Here, we surveyed clinical genetic sequencing data in S. aureus to distinguish natural amino acid variations in DHPS from those that are associated with sulfonamide resistance. Five mutations were identified, F17L, S18L, T51M, E208K, and KE257_dup. Their contribution to resistance and their cost to the catalytic properties of DHPS were evaluated using a combination of biochemical, biophysical and microbiological susceptibility studies. These studies show that F17L, S18L, and T51M directly lead to sulfonamide resistance while unexpectedly increasing susceptibility to trimethoprim, which targets the downstream enzyme dihydrofolate reductase. The secondary mutations E208K and KE257_dup restore trimethoprim susceptibility closer to wild-type levels while further increasing sulfonamide resistance. Structural studies reveal that these mutations appear to selectively disfavor the binding of the sulfonamides by sterically blocking an outer ring moiety that is not present in the substrate. This emphasizes that new inhibitors must be designed that strictly stay within the substrate volume in the context of the transition state.
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Affiliation(s)
- Elizabeth C. Griffith
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Miranda J. Wallace
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, United States
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Yinan Wu
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Gyanendra Kumar
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Stefan Gajewski
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Pamela Jackson
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Gregory A. Phelps
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, United States
- Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Zhong Zheng
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Charles O. Rock
- Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Richard E. Lee
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Stephen W. White
- Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, United States
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, United States
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7
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Folate biosynthesis pathway: mechanisms and insights into drug design for infectious diseases. Future Med Chem 2018; 10:935-959. [PMID: 29629843 DOI: 10.4155/fmc-2017-0168] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Folate pathway is a key target for the development of new drugs against infectious diseases since the discovery of sulfa drugs and trimethoprim. The knowledge about this pathway has increased in the last years and the catalytic mechanism and structures of all enzymes of the pathway are fairly understood. In addition, differences among enzymes from prokaryotes and eukaryotes could be used for the design of specific inhibitors. In this review, we show a panorama of progress that has been achieved within the folate pathway obtained in the last years. We explored the structure and mechanism of enzymes, several genetic features, strategies, and approaches used in the design of new inhibitors that have been used as targets in pathogen chemotherapy.
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8
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Jongkon N, Gleeson D, Gleeson MP. Elucidation of the catalytic mechanism of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase using QM/MM calculations. Org Biomol Chem 2018; 16:6239-6249. [DOI: 10.1039/c8ob01428k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This account describes the application of QM/MM calculations to understand the reaction mechanism of HPPK, an important pharmacological target on the folate pathway for the treatment of diseases including anti-microbial resistance, malaria and cancer.
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Affiliation(s)
- Nathjanan Jongkon
- Department of Social and Applied Science
- College of Industrial Technology
- King Mongkut's University of Technology North Bangkok
- Bangkok 10800
- Thailand
| | - Duangkamol Gleeson
- Department of Chemistry
- Faculty of Science
- King Mongkut's Institute of Technology Ladkrabang
- Thailand
| | - M. Paul Gleeson
- Department of Biomedical Engineering
- Faculty of Engineering
- King Mongkut's Institute of Technology Ladkrabang
- Bangkok 10520
- Thailand
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9
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Marimuthu P, Singaravelu K, Namasivayam V. Probing the binding mechanism of mercaptoguanine derivatives as inhibitors of HPPK by docking and molecular dynamics simulations. J Biomol Struct Dyn 2016; 35:3507-3521. [PMID: 27844507 DOI: 10.1080/07391102.2016.1260496] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a promising antimicrobial target involved in the folate biosynthesis pathway. Although, the results from crystallographic studies of HPPK have attracted a great interest in the design of novel HPPK inhibitors, the mechanism of action of HPPK due to inhibitor binding remains questionable. Recently, mercaptoguanine derivatives were reported to inhibit the pyrophosphoryl transfer mechanism of Staphylococcus aureus HPPK (SaHPPK). The present study is an attempt to understand the SaHPPK-inhibitors binding mechanism and to highlight the key residues that possibly involve in the complex formation. To decipher these questions, we used the state-of-the-art advanced insilico approach such as molecular docking, molecular dynamics (MD), molecular mechanics-generalized Born surface area approach. Domain cross correlation and principle component analysis were applied to the snapshots obtained from MD revealed that the compounds with high binding affinity stabilize the conformational dynamics of SaHPPK. The binding free energy estimation showed that the van der Waals and electrostatic interactions played a vital role for the binding mechanism. Additionally, the predicted binding free energy was in good agreement with the experimental values (R2 = .78). Moreover, the free energy decomposition on per-residue confirms the key residues that significantly contribute to the complex formation. These results are expected to be useful for rational design of novel SaHPPK inhibitors.
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Affiliation(s)
- Parthiban Marimuthu
- a Structural Bioinformatics Laboratory (SBL), Faculty of Science and Engineering , Åbo Akademi University , Turku FI-20520 , Finland
| | - Kalaimathy Singaravelu
- b Department of Information Technology, Turku Centre for Biotechnology , University of Turku , Turku FI-20520 , Finland
| | - Vigneshwaran Namasivayam
- c PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry II , University of Bonn , An der Immenburg 4, Bonn D-53121 , Germany
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10
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Dennis ML, Pitcher NP, Lee MD, DeBono AJ, Wang ZC, Harjani JR, Rahmani R, Cleary B, Peat TS, Baell JB, Swarbrick JD. Structural Basis for the Selective Binding of Inhibitors to 6-Hydroxymethyl-7,8-dihydropterin Pyrophosphokinase from Staphylococcus aureus and Escherichia coli. J Med Chem 2016; 59:5248-63. [PMID: 27094768 DOI: 10.1021/acs.jmedchem.6b00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a member of the folate biosynthesis pathway found in prokaryotes and lower eukaryotes that catalyzes the pyrophosphoryl transfer from the ATP cofactor to a 6-hydroxymethyl-7,8-dihydropterin substrate. We report the chemical synthesis of a series of S-functionalized 8-mercaptoguanine (8MG) analogues as substrate site inhibitors of HPPK and quantify binding against the E. coli and S. aureus enzymes (EcHPPK and SaHPPK). The results demonstrate that analogues incorporating acetophenone-based substituents have comparable affinities for both enzymes. Preferential binding of benzyl-substituted 8MG derivatives to SaHPPK was reconciled when a cryptic pocket unique to SaHPPK was revealed by X-ray crystallography. Differential chemical shift perturbation analysis confirmed this to be a common mode of binding for this series to SaHPPK. One compound (41) displayed binding affinities of 120 nM and 1.76 μM for SaHPPK and EcHPPK, respectively, and represents a lead for the development of more potent and selective inhibitors of SaHPPK.
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Affiliation(s)
- Matthew L Dennis
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.,CSIRO Biosciences Program , Parkville, Victoria 3052, Australia
| | - Noel P Pitcher
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Michael D Lee
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Aaron J DeBono
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Zhong-Chang Wang
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.,State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University , Nanjing 210093, People's Republic of China
| | - Jitendra R Harjani
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Raphaël Rahmani
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Ben Cleary
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Thomas S Peat
- CSIRO Biosciences Program , Parkville, Victoria 3052, Australia
| | - Jonathan B Baell
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - James D Swarbrick
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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11
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Dennis ML, Chhabra S, Wang ZC, Debono A, Dolezal O, Newman J, Pitcher NP, Rahmani R, Cleary B, Barlow N, Hattarki M, Graham B, Peat TS, Baell JB, Swarbrick JD. Structure-based design and development of functionalized Mercaptoguanine derivatives as inhibitors of the folate biosynthesis pathway enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Staphylococcus aureus. J Med Chem 2014; 57:9612-26. [PMID: 25357262 DOI: 10.1021/jm501417f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), an enzyme from the folate biosynthesis pathway, catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin and is a yet-to-be-drugged antimicrobial target. Building on our previous discovery that 8-mercaptoguanine (8MG) is an inhibitor of Staphylococcus aureus HPPK (SaHPPK), we have identified and characterized the binding of an S8-functionalized derivative (3). X-ray structures of both the SaHPPK/3/cofactor analogue ternary and the SaHPPK/cofactor analogue binary complexes have provided insight into cofactor recognition and key residues that move over 30 Å upon binding of 3, whereas NMR measurements reveal a partially plastic ternary complex active site. Synthesis and binding analysis of a set of analogues of 3 have identified an advanced new lead compound (11) displaying >20-fold higher affinity for SaHPPK than 8MG. A number of these exhibited low micromolar affinity for dihydropteroate synthase (DHPS), the adjacent, downstream enzyme to HPPK, and may thus represent promising new leads to bienzyme inhibitors.
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Affiliation(s)
- Matthew L Dennis
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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