1
|
Brown AC, Suess DLM. Valence Localization in Alkyne and Alkene Adducts of Synthetic [Fe 4S 4] + Clusters. Inorg Chem 2023; 62:1911-1918. [PMID: 35704768 PMCID: PMC9751231 DOI: 10.1021/acs.inorgchem.2c01353] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reported herein are alkyne and alkene adducts of synthetic [Fe4S4]+ clusters that model intermediates and inhibitor-bound states in enzymes involved in isoprenoid biosynthesis. Treatment of the N-heterocyclic carbene-ligated cluster [(IMes)3Fe4S4(OEt2)][BArF4] (IMes = 1,3-dimesitylimidazol-2-ylidene; [BArF4]- = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with phenylacetylene (PhCCH) or cis-cyclooctene (COE) results in displacement of the Et2O ligand to yield the corresponding π complexes, [(IMes)3Fe4S4(PhCCH)][BArF4] and [(IMes)3Fe4S4(COE)][BArF4]. EPR spectroscopic analysis demonstrates that both clusters are doublets with giso > 2 and thus are spectroscopically faithful models of the analogous species characterized in the isoprenoid biosynthetic enzymes IspG and IspH. Structural and Mössbauer spectroscopic analysis reveals that both complexes are best described as [Fe4S4]+ clusters in which the unique Fe site engages in modest back-bonding to the π-acidic ligand. Paramagnetic NMR studies show that, even at room temperature, the alkyne/alkene-bound Fe centers harbor minority spin and therefore adopt an Fe2+ valence. We propose that such valence localization could likewise occur in Fe-S enzymes that interact with π-acidic molecules.
Collapse
|
2
|
Jobelius H, Bianchino GI, Borel F, Chaignon P, Seemann M. The Reductive Dehydroxylation Catalyzed by IspH, a Source of Inspiration for the Development of Novel Anti-Infectives. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030708. [PMID: 35163971 PMCID: PMC8837944 DOI: 10.3390/molecules27030708] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/11/2022] [Accepted: 01/18/2022] [Indexed: 11/16/2022]
Abstract
The non-mevalonate or also called MEP pathway is an essential route for the biosynthesis of isoprenoid precursors in most bacteria and in microorganisms belonging to the Apicomplexa phylum, such as the parasite responsible for malaria. The absence of this pathway in mammalians makes it an interesting target for the discovery of novel anti-infectives. As last enzyme of this pathway, IspH is an oxygen sensitive [4Fe-4S] metalloenzyme that catalyzes 2H+/2e− reductions and a water elimination by involving non-conventional bioinorganic and bioorganometallic intermediates. After a detailed description of the discovery of the [4Fe-4S] cluster of IspH, this review focuses on the IspH mechanism discussing the results that have been obtained in the last decades using an approach combining chemistry, enzymology, crystallography, spectroscopies, and docking calculations. Considering the interesting druggability of this enzyme, a section about the inhibitors of IspH discovered up to now is reported as well. The presented results constitute a useful and rational help to inaugurate the design and development of new potential chemotherapeutics against pathogenic organisms.
Collapse
Affiliation(s)
- Hannah Jobelius
- Equipe Chimie Biologique et Applications Thérapeutiques, Institut de Chimie de Strasbourg UMR 7177, Université de Strasbourg/CNRS, 4, rue Blaise Pascal, 67070 Strasbourg, France; (H.J.); (G.I.B.); (P.C.)
| | - Gabriella Ines Bianchino
- Equipe Chimie Biologique et Applications Thérapeutiques, Institut de Chimie de Strasbourg UMR 7177, Université de Strasbourg/CNRS, 4, rue Blaise Pascal, 67070 Strasbourg, France; (H.J.); (G.I.B.); (P.C.)
| | - Franck Borel
- Institut de Biologie Structurale, Université Grenoble Alpes/CEA/CNRS, 38000 Grenoble, France;
| | - Philippe Chaignon
- Equipe Chimie Biologique et Applications Thérapeutiques, Institut de Chimie de Strasbourg UMR 7177, Université de Strasbourg/CNRS, 4, rue Blaise Pascal, 67070 Strasbourg, France; (H.J.); (G.I.B.); (P.C.)
| | - Myriam Seemann
- Equipe Chimie Biologique et Applications Thérapeutiques, Institut de Chimie de Strasbourg UMR 7177, Université de Strasbourg/CNRS, 4, rue Blaise Pascal, 67070 Strasbourg, France; (H.J.); (G.I.B.); (P.C.)
- Correspondence:
| |
Collapse
|
3
|
Affiliation(s)
- Annika Frank
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Michael Groll
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| |
Collapse
|
4
|
Saggu GS, Pala ZR, Garg S, Saxena V. New Insight into Isoprenoids Biosynthesis Process and Future Prospects for Drug Designing in Plasmodium. Front Microbiol 2016; 7:1421. [PMID: 27679614 PMCID: PMC5020098 DOI: 10.3389/fmicb.2016.01421] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/26/2016] [Indexed: 12/20/2022] Open
Abstract
The MEP (Methyl Erythritol Phosphate) isoprenoids biosynthesis pathway is an attractive drug target to combat malaria, due to its uniqueness and indispensability for the parasite. It is functional in the apicoplast of Plasmodium and its products get transported to the cytoplasm, where they participate in glycoprotein synthesis, electron transport chain, tRNA modification and several other biological processes. Several compounds have been tested against the enzymes involved in this pathway and amongst them Fosmidomycin, targeted against IspC (DXP reductoisomerase) enzyme and MMV008138 targeted against IspD enzyme have shown good anti-malarial activity in parasite cultures. Fosmidomycin is now-a-days prescribed clinically, however, less absorption, shorter half-life, and toxicity at higher doses, limits its use as an anti-malarial. The potential of other enzymes of the pathway as candidate drug targets has also been determined. This review details the various drug molecules tested against these targets with special emphasis to Plasmodium. We corroborate that MEP pathway functional within the apicoplast of Plasmodium is a major drug target, especially during erythrocytic stages. However, the major bottlenecks, bioavailability and toxicity of the new molecules needs to be addressed, before considering any new molecule as a potent antimalarial.
Collapse
Affiliation(s)
- Gagandeep S Saggu
- Molecular Parasitology and Systems Biology Laboratory, Department of Biological Sciences, Birla Institute of Technology and Science Pilani, India
| | - Zarna R Pala
- Molecular Parasitology and Systems Biology Laboratory, Department of Biological Sciences, Birla Institute of Technology and Science Pilani, India
| | - Shilpi Garg
- Molecular Parasitology and Systems Biology Laboratory, Department of Biological Sciences, Birla Institute of Technology and Science Pilani, India
| | - Vishal Saxena
- Molecular Parasitology and Systems Biology Laboratory, Department of Biological Sciences, Birla Institute of Technology and Science Pilani, India
| |
Collapse
|
5
|
Masini T, Hirsch AKH. Development of Inhibitors of the 2C-Methyl-d-erythritol 4-Phosphate (MEP) Pathway Enzymes as Potential Anti-Infective Agents. J Med Chem 2014; 57:9740-63. [DOI: 10.1021/jm5010978] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Tiziana Masini
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh
7, NL-9747
AG Groningen, The Netherlands
| | - Anna K. H. Hirsch
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh
7, NL-9747
AG Groningen, The Netherlands
| |
Collapse
|
6
|
Wang W, Oldfield E. Biometallorganische Chemie mit IspG und IspH: Struktur, Funktion und Hemmung der an der Isoprenoid-Biosynthese beteiligten [Fe 4S 4]-Proteine. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201306712] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
7
|
Wang W, Oldfield E. Bioorganometallic chemistry with IspG and IspH: structure, function, and inhibition of the [Fe(4)S(4)] proteins involved in isoprenoid biosynthesis. Angew Chem Int Ed Engl 2014; 53:4294-310. [PMID: 24481599 DOI: 10.1002/anie.201306712] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Indexed: 11/12/2022]
Abstract
Enzymes of the methylerythritol phosphate pathway of isoprenoid biosynthesis are attractive anti-infective drug targets. The last two enzymes of this pathway, IspG and IspH, are [Fe4 S4 ] proteins that are not produced by humans and catalyze 2 H(+) / 2 e(-) reductions with novel mechanisms. In this Review, we summarize recent advances in structural, mechanistic, and inhibitory studies of these two enzymes. In particular, mechanistic proposals involving bioorganometallic intermediates are presented, and compared with other mechanistic possibilities. In addition, inhibitors based on substrate analogues as well as developed by rational design and compound-library screening, are discussed. The results presented support bioorganometallic catalytic mechanisms for IspG and IspH, and open up new routes to anti-infective drug design targeting [Fe4 S4 ] clusters in proteins.
Collapse
Affiliation(s)
- Weixue Wang
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | | |
Collapse
|
8
|
Wang W, Wang K, Span I, Jauch J, Bacher A, Groll M, Oldfield E. Are free radicals involved in IspH catalysis? An EPR and crystallographic investigation. J Am Chem Soc 2012; 134:11225-34. [PMID: 22687151 DOI: 10.1021/ja303445z] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The [4Fe-4S] protein IspH in the methylerythritol phosphate isoprenoid biosynthesis pathway is an important anti-infective drug target, but its mechanism of action is still the subject of debate. Here, by using electron paramagnetic resonance (EPR) spectroscopy and (2)H, (17)O, and (57)Fe isotopic labeling, we have characterized and assigned two key reaction intermediates in IspH catalysis. The results are consistent with the bioorganometallic mechanism proposed earlier, and the mechanism is proposed to have similarities to that of ferredoxin, thioredoxin reductase, in that one electron is transferred to the [4Fe-4S](2+) cluster, which then performs a formal two-electron reduction of its substrate, generating an oxidized high potential iron-sulfur protein (HiPIP)-like intermediate. The two paramagnetic reaction intermediates observed correspond to the two intermediates proposed in the bioorganometallic mechanism: the early π-complex in which the substrate's 3-CH(2)OH group has rotated away from the reduced iron-sulfur cluster, and the next, η(3)-allyl complex formed after dehydroxylation. No free radical intermediates are observed, and the two paramagnetic intermediates observed do not fit in a Birch reduction-like or ferraoxetane mechanism. Additionally, we show by using EPR spectroscopy and X-ray crystallography that two substrate analogues (4 and 5) follow the same reaction mechanism.
Collapse
Affiliation(s)
- Weixue Wang
- Center for Biophysics and Computational Biology, 607 South Mathews Avenue, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | | | | | | | | | | |
Collapse
|
9
|
Barnes EC, Choomuenwai V, Andrews KT, Quinn RJ, Davis RA. Design and synthesis of screening libraries based on the muurolane natural product scaffold. Org Biomol Chem 2012; 10:4015-23. [DOI: 10.1039/c2ob00029f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
|
11
|
Oldfield E. Targeting isoprenoid biosynthesis for drug discovery: bench to bedside. Acc Chem Res 2010; 43:1216-26. [PMID: 20560544 DOI: 10.1021/ar100026v] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The isoprenoid biosynthesis pathways produce the largest class of small molecules in Nature: isoprenoids (also called terpenoids). Not surprisingly then, isoprenoid biosynthesis is a target for drug discovery, and many drugs--such as Lipitor (used to lower cholesterol), Fosamax (used to treat osteoporosis), and many anti-infectives--target isoprenoid biosynthesis. However, drug resistance in malaria, tuberculosis, and staph infections is rising, cheap and effective drugs for the neglected tropical diseases are lacking, and progress in the development of anticancer drugs is relatively slow. Isoprenoid biosynthesis is thus an attractive target, and in this Account, I describe developments in four areas, using in each case knowledge derived from one area of chemistry to guide the development of inhibitors (or drug leads) in another, seemingly unrelated, area. First, I describe mechanistic studies of the enzyme IspH, which is present in malaria parasites and most pathogenic bacteria, but not in humans. IspH is a 4Fe-4S protein and produces the five-carbon (C5) isoprenoids IPP (isopentenyl diphosphate) and DMAPP (dimethylallyl diphosphate) from HMBPP (E-1-hydroxy-2-methyl-but-2-enyl-4-diphosphate) via a 2H(+)/2e(-) reduction (of an allyl alcohol to an alkene). The mechanism is unusual in that it involves organometallic species: "metallacycles" (η(2)-alkenes) and η(1)/η(3)-allyls. These observations lead to novel alkyne inhibitors, which also form metallacycles. Second, I describe structure-function-inhibition studies of FPP synthase, the macromolecule that condenses IPP and DMAPP to the sesquiterpene farnesyl diphosphate (FPP) in a "head-to-tail" manner. This enzyme uses a carbocation mechanism and is potently inhibited by bone resorption drugs (bisphosphonates), which I show are also antiparasitic agents that block sterol biosynthesis in protozoa. Moreover, "lipophilic" bisphosphonates inhibit protein prenylation and invasiveness in tumor cells, in addition to activating γδ T-cells to kill tumor cells, and are important new leads in oncology. Third, I describe structural and inhibition studies of a "head-to-head" triterpene synthase, dehydrosqualene synthase (CrtM), from Staphylococcus aureus. CrtM catalyzes the first committed step in biosynthesis of the carotenoid virulence factor staphyloxanthin: the condensation of two FPP molecules to produce a cyclopropane (presqualene diphosphate). The structure of CrtM is similar to that of human squalene synthase (SQS), and some SQS inhibitors (originally developed as cholesterol-lowering drugs) block staphyloxanthin biosynthesis. Treated bacteria are white and nonvirulent (because they lack the carotenoid shield that protects them from reactive oxygen species produced by neutrophils), rendering them susceptible to innate immune system clearance--a new therapeutic approach. And finally, I show that the heart drug amiodarone, also known to have antifungal activity, blocks ergosterol biosynthesis at the level of oxidosqualene cyclase in Trypanosoma cruzi, work that has led to its use in the clinic as a novel antiparasitic agent. In each of these four examples, I use information from one area (organometallic chemistry, bone resorption drugs, cholesterol-lowering agents, heart disease) to develop drug leads in an unrelated area: a "knowledge-based" approach that represents an important advance in the search for new drugs.
Collapse
Affiliation(s)
- Eric Oldfield
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801
| |
Collapse
|
12
|
Wang K, Wang W, No JH, Zhang Y, Zhang Y, Oldfield E. Inhibition of the Fe(4)S(4)-cluster-containing protein IspH (LytB): electron paramagnetic resonance, metallacycles, and mechanisms. J Am Chem Soc 2010; 132:6719-27. [PMID: 20426416 DOI: 10.1021/ja909664j] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the inhibition of the Aquifex aeolicus IspH enzyme (LytB, (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate reductase, EC 1.17.1.2) by a series of diphosphates and bisphosphonates. The most active species was an alkynyl diphosphate having IC(50) = 0.45 microM (K(i) approximately 60 nM), which generated a very large change in the 9 GHz EPR spectrum of the reduced protein. On the basis of previous work on organometallic complexes, together with computational docking and quantum chemical calculations, we propose a model for alkyne inhibition involving pi (or pi/sigma) "metallacycle" complex formation with the unique fourth Fe in the Fe(4)S(4) cluster. Aromatic species had less activity, and for these we propose an inhibition model based on an electrostatic interaction with the active site E126. Overall, the results are of broad general interest since they not only represent the first potent IspH inhibitors but also suggest a conceptually new approach to inhibiting other Fe(4)S(4)-cluster-containing proteins that are of interest as drug and herbicide targets.
Collapse
Affiliation(s)
- Ke Wang
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | | | | | | | | |
Collapse
|
13
|
Wang W, Li J, Wang K, Huang C, Zhang Y, Oldfield E. Organometallic mechanism of action and inhibition of the 4Fe-4S isoprenoid biosynthesis protein GcpE (IspG). Proc Natl Acad Sci U S A 2010; 107:11189-93. [PMID: 20534554 PMCID: PMC2895101 DOI: 10.1073/pnas.1000264107] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report the results of a series of chemical, EPR, ENDOR, and HYSCORE spectroscopic investigations of the mechanism of action (and inhibition) of GcpE, E-1-hydroxy-2-methyl-but-2-enyl-4-diphosphate (HMBPP) synthase, also known as IspG, an Fe(4)S(4) cluster-containing protein. We find that the epoxide of HMBPP when reduced by GcpE generates the same transient EPR species as observed on addition of the substrate, 2-C-methyl-D-erythritol-2, 4-cyclo-diphosphate. ENDOR and HYSCORE spectra of these transient species (using (2)H, (13)C and (17)O labeled samples) indicate formation of an Fe-C-H containing organometallic intermediate, most likely a ferraoxetane. This is then rapidly reduced to a ferracyclopropane in which the HMBPP product forms an eta(2)-alkenyl pi- (or pi/sigma) complex with the 4th Fe in the Fe(4)S(4) cluster, and a similar "metallacycle" also forms between isopentenyl diphosphate (IPP) and GcpE. Based on this metallacycle concept, we show that an alkyne (propargyl) diphosphate is a good (K(i) approximately 300 nM) GcpE inhibitor, and supported again by EPR and ENDOR results (a (13)C hyperfine coupling of approximately 7 MHz), as well as literature precedent, we propose that the alkyne forms another pi/sigma metallacycle, an eta(2)-alkynyl, or ferracyclopropene. Overall, the results are of broad general interest because they provide new mechanistic insights into GcpE catalysis and inhibition, with organometallic bond formation playing, in both cases, a key role.
Collapse
Affiliation(s)
- Weixue Wang
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 607 South Mathews Avenue, Urbana, IL 61801
| | - Jikun Li
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 607 South Mathews Avenue, Urbana, IL 61801
| | - Ke Wang
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801; and
| | - Cancan Huang
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 607 South Mathews Avenue, Urbana, IL 61801
| | - Yong Zhang
- Department of Chemistry and Biochemistry, University of Southern Mississippi, 118 College Drive #5043, Hattiesburg, MS 39406
| | - Eric Oldfield
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 607 South Mathews Avenue, Urbana, IL 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801; and
| |
Collapse
|