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Nguyen TN, Ingle C, Thompson S, Reynolds KA. The genetic landscape of a metabolic interaction. Nat Commun 2024; 15:3351. [PMID: 38637543 PMCID: PMC11026382 DOI: 10.1038/s41467-024-47671-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 04/09/2024] [Indexed: 04/20/2024] Open
Abstract
While much prior work has explored the constraints on protein sequence and evolution induced by physical protein-protein interactions, the sequence-level constraints emerging from non-binding functional interactions in metabolism remain unclear. To quantify how variation in the activity of one enzyme constrains the biochemical parameters and sequence of another, we focus on dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), a pair of enzymes catalyzing consecutive reactions in folate metabolism. We use deep mutational scanning to quantify the growth rate effect of 2696 DHFR single mutations in 3 TYMS backgrounds under conditions selected to emphasize biochemical epistasis. Our data are well-described by a relatively simple enzyme velocity to growth rate model that quantifies how metabolic context tunes enzyme mutational tolerance. Together our results reveal the structural distribution of epistasis in a metabolic enzyme and establish a foundation for the design of multi-enzyme systems.
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Affiliation(s)
- Thuy N Nguyen
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- The Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- The Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Form Bio, Dallas, TX, 75226, USA
| | - Christine Ingle
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- The Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- The Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Samuel Thompson
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, 94158, USA
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Kimberly A Reynolds
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- The Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- The Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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2
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Nguyen TN, Ingle C, Thompson S, Reynolds KA. The Genetic Landscape of a Metabolic Interaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.28.542639. [PMID: 37645784 PMCID: PMC10461916 DOI: 10.1101/2023.05.28.542639] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Enzyme abundance, catalytic activity, and ultimately sequence are all shaped by the need of growing cells to maintain metabolic flux while minimizing accumulation of deleterious intermediates. While much prior work has explored the constraints on protein sequence and evolution induced by physical protein-protein interactions, the sequence-level constraints emerging from non-binding functional interactions in metabolism remain unclear. To quantify how variation in the activity of one enzyme constrains the biochemical parameters and sequence of another, we focused on dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), a pair of enzymes catalyzing consecutive reactions in folate metabolism. We used deep mutational scanning to quantify the growth rate effect of 2,696 DHFR single mutations in 3 TYMS backgrounds under conditions selected to emphasize biochemical epistasis. Our data are well-described by a relatively simple enzyme velocity to growth rate model that quantifies how metabolic context tunes enzyme mutational tolerance. Together our results reveal the structural distribution of epistasis in a metabolic enzyme and establish a foundation for the design of multi-enzyme systems.
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Affiliation(s)
- Thuy N. Nguyen
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
| | - Christine Ingle
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
| | - Samuel Thompson
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Kimberly A. Reynolds
- The Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, USA, 75390
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3
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Polizzi NF, DeGrado WF. A defined structural unit enables de novo design of small-molecule-binding proteins. Science 2020; 369:1227-1233. [PMID: 32883865 PMCID: PMC7526616 DOI: 10.1126/science.abb8330] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 06/29/2020] [Indexed: 12/21/2022]
Abstract
The de novo design of proteins that bind highly functionalized small molecules represents a great challenge. To enable computational design of binders, we developed a unit of protein structure-a van der Mer (vdM)-that maps the backbone of each amino acid to statistically preferred positions of interacting chemical groups. Using vdMs, we designed six de novo proteins to bind the drug apixaban; two bound with low and submicromolar affinity. X-ray crystallography and mutagenesis confirmed a structure with a precisely designed cavity that forms favorable interactions in the drug-protein complex. vdMs may enable design of functional proteins for applications in sensing, medicine, and catalysis.
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Affiliation(s)
- Nicholas F Polizzi
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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4
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Sapienza PJ, Popov KI, Mowrey DD, Falk BT, Dokholyan NV, Lee AL. Inter-Active Site Communication Mediated by the Dimer Interface β-Sheet in the Half-the-Sites Enzyme, Thymidylate Synthase. Biochemistry 2019; 58:3302-3313. [PMID: 31283187 DOI: 10.1021/acs.biochem.9b00486] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thymidylate synthase (TS) is a dimeric enzyme conserved in all life forms that exhibits the allosteric feature of half-the-sites activity. Neither the reason for nor the mechanism of this phenomenon is understood. We used a combined nuclear magnetic resonance (NMR) and molecular dynamics approach to study a stable intermediate preceding hydride transfer, which is the rate-limiting and half-the-sites step. In NMR titrations with ligands leading to this intermediate, we measured chemical shifts of the apoenzyme (lig0), the saturated holoenzyme (lig2), and the typically elusive singly bound (lig1) states. Approximately 40 amides showed quartet patterns providing direct NMR evidence of coupling between the active site and probes >30 Å away in the distal subunit. Quartet peak patterns have symmetrical character, indicating reciprocity in communicating the first and second binding events to the distal protomer. Quartets include key catalytic residues and map to the dimer interface β-sheet, which also represents the shortest path between the two active sites. Simulations corroborate the coupling observed in solution in that there is excellent overlap between quartet residues and main-chain atoms having intersubunit cross-correlated motions. Simulations identify five hot spot residues, three of which lie at the kink in the unique β-bulge abutting the active sites on either end of the sheet. Interstrand cross-correlated motions become more organized and pronounced as the enzyme progresses from lig0 to lig1 and ultimately lig2. Coupling in the apparently symmetrical complex has implications for half-the-sites reactivity and potentially resolves the paradox of inequivalent TS active sites despite the vast majority of X-ray structures appearing to be symmetrical.
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Affiliation(s)
- Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-7355 , United States
| | - Konstantin I Popov
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - David D Mowrey
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Bradley T Falk
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Nikolay V Dokholyan
- Department of Pharmacology and Department of Biochemistry and Molecular Biology , Penn State College of Medicine , Hershey , Pennsylvania 17033 , United States.,Department of Chemistry and Department of Biomedical Engineering , The Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-7355 , United States.,Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
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5
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Structural Comparison of Enterococcus faecalis and Human Thymidylate Synthase Complexes with the Substrate dUMP and Its Analogue FdUMP Provides Hints about Enzyme Conformational Variabilities. Molecules 2019; 24:molecules24071257. [PMID: 30935102 PMCID: PMC6479881 DOI: 10.3390/molecules24071257] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 03/22/2019] [Accepted: 03/28/2019] [Indexed: 12/17/2022] Open
Abstract
Thymidylate synthase (TS) is an enzyme of paramount importance as it provides the only de novo source of deoxy-thymidine monophosphate (dTMP). dTMP, essential for DNA synthesis, is produced by the TS-catalyzed reductive methylation of 2′-deoxyuridine-5′-monophosphate (dUMP) using N5,N10-methylenetetrahydrofolate (mTHF) as a cofactor. TS is ubiquitous and a validated drug target. TS enzymes from different organisms differ in sequence and structure, but are all obligate homodimers. The structural and mechanistic differences between the human and bacterial enzymes are exploitable to obtain selective inhibitors of bacterial TSs that can enrich the currently available therapeutic tools against bacterial infections. Enterococcus faecalis is a pathogen fully dependent on TS for dTMP synthesis. In this study, we present four new crystal structures of Enterococcus faecalis and human TSs in complex with either the substrate dUMP or the inhibitor FdUMP. The results provide new clues about the half-site reactivity of Enterococcus faecalis TS and the mechanisms underlying the conformational changes occurring in the two enzymes. We also identify relevant differences in cofactor and inhibitor binding between Enterococcus faecalis and human TS that can guide the design of selective inhibitors against bacterial TSs.
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Gurevic I, Islam Z, Świderek K, Trepka K, Ghosh AK, Moliner V, Kohen A. Experimental and Computational Studies Delineate the Role of Asparagine 177 in Hydride Transfer for E. coli Thymidylate Synthase. ACS Catal 2018; 8:10241-10253. [PMID: 31275729 DOI: 10.1021/acscatal.8b02554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thymidylate synthase (TSase), an enzyme responsible for the de novo biosynthesis of 2'-deoxythymidine 5'-monophosphate (thymidylate, dTMP) necessary for DNA synthesis, has been a drug target for decades. TSase is a highly conserved enzyme across species ranging from very primitive organisms to mammals. Among the many conserved active site residues, an asparagine (N177, using Escherichia coli residues numbering) appears to make direct hydrogen bonds with both the C4=O4 carbonyl of the 2'-deoxyuridine 5'-monophosphate (uridylate, dUMP) substrate and its pyrimidine ring's N3. Recent studies have reassessed the TSase catalytic mechanism, focusing on the degree of negative charge accumulation at the O4 carbonyl of the substrate during two critical H-transfers - a proton abstraction and a hydride transfer. To obtain insights into the role of this conserved N177 on the hydride transfer, we examined its aspartic acid (D) and serine (S) mutants - each of which is expected to alter hydrogen bonding and charge stabilization around the C4=O4 carbonyl of the 2'-deoxyuridine 5'-monophosphate (uridylate, dUMP) substrate. Steady-state kinetics, substrate binding order studies and temperature-dependency analysis of intrinsic KIEs for the hydride transfer step of the TSase catalytic cycle suggest the active site of N177D is not precisely organized for that step. A smaller disruption was observed for N177S, which could be rationalized by partial compensation by water molecules and rearrangement of other residues toward preparation of the system for the hydride transfer under study. These experimental findings are qualitatively mirrored by QM/MM computational simulations, thereby shedding light on the sequence and synchronicity of steps in the TSase-catalyzed reaction. This information could potentially inform the design of mechanism-based drugs targeting this enzyme.
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Affiliation(s)
- Ilya Gurevic
- Department of Chemistry, College of Liberal Arts & Sciences, University of Iowa, Iowa City, Iowa 52242-1727, United States
| | - Zahidul Islam
- Department of Chemistry, College of Liberal Arts & Sciences, University of Iowa, Iowa City, Iowa 52242-1727, United States
| | - Katarzyna Świderek
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
| | - Kai Trepka
- Department of Chemistry, College of Liberal Arts & Sciences, University of Iowa, Iowa City, Iowa 52242-1727, United States
| | - Ananda K. Ghosh
- Department of Chemistry, College of Liberal Arts & Sciences, University of Iowa, Iowa City, Iowa 52242-1727, United States
| | - Vicent Moliner
- Departament de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
| | - Amnon Kohen
- Department of Chemistry, College of Liberal Arts & Sciences, University of Iowa, Iowa City, Iowa 52242-1727, United States
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7
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Lee AL, Sapienza PJ. Thermodynamic and NMR Assessment of Ligand Cooperativity and Intersubunit Communication in Symmetric Dimers: Application to Thymidylate Synthase. Front Mol Biosci 2018; 5:47. [PMID: 29888227 PMCID: PMC5981203 DOI: 10.3389/fmolb.2018.00047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 04/23/2018] [Indexed: 01/17/2023] Open
Abstract
Thymidylate synthase (TS) is a homodimeric enzyme with evidence for negative regulation of one protomer while the other protomer acts on substrate, so called half-the-sites reactivity. The mechanisms by which multisubunit allosteric proteins communicate between protomers is not well understood, and the simplicity of dimeric systems has advantages for observing conformational and dynamic processes that functionally connect distance-separated active sites. This review considers progress in overcoming the inherent challenges of accurate thermodynamic and atomic-resolution characterization of interprotomer communication mechanisms in symmetric protein dimers, with TS used as an example. Isothermal titration calorimetry (ITC) is used to measure ligand binding cooperativity, even in cases where the two binding enthalpies are similar, and NMR spectroscopy is used to detect site-specific changes occurring in the two protomers. The NMR approach makes use of mixed-labeled dimers, enabling protomer-specific detection of signals in the singly ligated state. The rich informational content of the NMR signals from the singly ligated state, relative to the apo and saturated states, requires new considerations that do not arise in simple cases of 1:1 protein-ligand interactions.
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Affiliation(s)
- Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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8
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Finer-Moore JS, Lee TT, Stroud RM. A Single Mutation Traps a Half-Sites Reactive Enzyme in Midstream, Explaining Asymmetry in Hydride Transfer. Biochemistry 2018; 57:2786-2795. [PMID: 29717875 DOI: 10.1021/acs.biochem.8b00176] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Escherichia coli thymidylate synthase (EcTS), rate-determining hydride transfer from the cofactor 5,10-methylene-5,6,7,8-tetrahydrofolate to the intermediate 5-methylene-2'-deoxyuridine 5'-monophosphate occurs by hydrogen tunneling, requiring precise alignment of reactants and a closed binding cavity, sealed by the C-terminal carboxyl group. Mutations that destabilize the closed conformation of the binding cavity allow small molecules such as β-mercaptoethanol (β-ME) to enter the active site and compete with hydride for addition to the 5-methylene group of the intermediate. The C-terminal deletion mutant of EcTS produced the β-ME adduct in proportions that varied dramatically with cofactor concentration, from 50% at low cofactor concentrations to 0% at saturating cofactor conditions, suggesting communication between active sites. We report the 2.4 Å X-ray structure of the C-terminal deletion mutant of E. coli TS in complex with a substrate and a cofactor analogue, CB3717. The structure is asymmetric, with reactants aligned in a manner consistent with hydride transfer in only one active site. In the second site, CB3717 has shifted to a site where the normal cofactor would be unlikely to form 5-methylene-2'-deoxyuridine 5'-monophosphate, consistent with no formation of the β-ME adduct. The structure shows how the binding of the cofactor at one site triggers hydride transfer and borrows needed stabilization from substrate binding at the second site. It indicates pathways through the dimer interface that contribute to allostery relevant to half-sites reactivity.
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Affiliation(s)
- Janet S Finer-Moore
- Department of Biochemistry and Biophysics , University of California , San Francisco , California 94143-2240 , United States
| | - Tom T Lee
- Department of Biochemistry and Biophysics , University of California , San Francisco , California 94143-2240 , United States
| | - Robert M Stroud
- Department of Biochemistry and Biophysics , University of California , San Francisco , California 94143-2240 , United States
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9
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Fanaei-Kahrani Z, Ganjalikhany MR, Rasa SMM, Emamzadeh R. New insights into the molecular characteristics behind the function of Renilla luciferase. J Cell Biochem 2017; 119:1780-1790. [PMID: 28796298 DOI: 10.1002/jcb.26339] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 08/09/2017] [Indexed: 01/10/2023]
Abstract
Renilla Luciferase (RLuc) is a blue light emitter protein which can be applied as a valuable tool in medical diagnosis. But due to lack of the crystal structure of RLuc-ligand complex, the functional motions and catalytic mechanism of this enzyme remain largely unknown. In the present study, the active site properties and the ligand-receptor interactions of the native RLuc and its red-shifted light emitting variant (Super RLuc 8) were investigated using molecular docking approach, molecular dynamics (MD) analysis, and MM-PBSA method. The detailed analysis of the main clusters led to identifying a lid-like structure and its functional motions. Furthermore, an induced-fit mechanism is proposed where ligand-binding induces conformational changes of the active site. Our findings give an insight into the deeper understanding of RLuc conformational changes during binding steps and ligand-receptor pattern. Moreover, our work broaden our understanding of how active site geometry is adjusted to support the catalytic activity and red-shifted light emission in Super RLuc 8.
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Affiliation(s)
- Zahra Fanaei-Kahrani
- Department of Biology, Faculty of Sciences, University of Isfahan, Isfahan, Iran
| | | | | | - Rahman Emamzadeh
- Department of Biology, Faculty of Sciences, University of Isfahan, Isfahan, Iran
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10
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Jarmuła A, Wilk P, Maj P, Ludwiczak J, Dowierciał A, Banaszak K, Rypniewski W, Cieśla J, Dąbrowska M, Frączyk T, Bronowska AK, Jakowiecki J, Filipek S, Rode W. Crystal structures of nematode (parasitic T. spiralis and free living C. elegans), compared to mammalian, thymidylate synthases (TS). Molecular docking and molecular dynamics simulations in search for nematode-specific inhibitors of TS. J Mol Graph Model 2017; 77:33-50. [PMID: 28826032 DOI: 10.1016/j.jmgm.2017.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/05/2017] [Accepted: 08/07/2017] [Indexed: 01/01/2023]
Abstract
Three crystal structures are presented of nematode thymidylate synthases (TS), including Caenorhabditis elegans (Ce) enzyme without ligands and its ternary complex with dUMP and Raltitrexed, and binary complex of Trichinella spiralis (Ts) enzyme with dUMP. In search of differences potentially relevant for the development of species-specific inhibitors of the nematode enzyme, a comparison was made of the present Ce and Ts enzyme structures, as well as binary complex of Ce enzyme with dUMP, with the corresponding mammalian (human, mouse and rat) enzyme crystal structures. To complement the comparison, tCONCOORD computations were performed to evaluate dynamic behaviors of mammalian and nematode TS structures. Finally, comparative molecular docking combined with molecular dynamics and free energy of binding calculations were carried out to search for ligands showing selective affinity to T. spiralis TS. Despite an overall strong similarity in structure and dynamics of nematode vs mammalian TSs, a pool of ligands demonstrating predictively a strong and selective binding to TsTS has been delimited. These compounds, the E63 family, locate in the dimerization interface of TsTS where they exert species-specific interactions with certain non-conserved residues, including hydrogen bonds with Thr174 and hydrophobic contacts with Phe192, Cys191 and Tyr152. The E63 family of ligands opens the possibility of future development of selective inhibitors of TsTS and effective agents against trichinellosis.
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Affiliation(s)
- Adam Jarmuła
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland.
| | - Piotr Wilk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland; Macromolecular Crystallography (BESSY-MX), Berlin, Germany
| | - Piotr Maj
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
| | - Jan Ludwiczak
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland; Centre of New Technologies, University of Warsaw, Warszawa, Poland
| | - Anna Dowierciał
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
| | - Katarzyna Banaszak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
| | - Wojciech Rypniewski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
| | - Joanna Cieśla
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
| | - Magdalena Dąbrowska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
| | - Tomasz Frączyk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
| | | | | | | | - Wojciech Rode
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland
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Shionyu-Mitsuyama C, Hijikata A, Tsuji T, Shirai T. Classification of ligand molecules in PDB with graph match-based structural superposition. ACTA ACUST UNITED AC 2016; 17:135-146. [PMID: 28012138 DOI: 10.1007/s10969-016-9209-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
The fast heuristic graph match algorithm for small molecules, COMPLIG, was improved by adding a structural superposition process to verify the atom-atom matching. The modified method was used to classify the small molecule ligands in the Protein Data Bank (PDB) by their three-dimensional structures, and 16,660 types of ligands in the PDB were classified into 7561 clusters. In contrast, a classification by a previous method (without structure superposition) generated 3371 clusters from the same ligand set. The characteristic feature in the current classification system is the increased number of singleton clusters, which contained only one ligand molecule in a cluster. Inspections of the singletons in the current classification system but not in the previous one implied that the major factors for the isolation were differences in chirality, cyclic conformations, separation of substructures, and bond length. Comparisons between current and previous classification systems revealed that the superposition-based classification was effective in clustering functionally related ligands, such as drugs targeted to specific biological processes, owing to the strictness of the atom-atom matching.
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Affiliation(s)
- Clara Shionyu-Mitsuyama
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Atsushi Hijikata
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Toshiyuki Tsuji
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Tsuyoshi Shirai
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan.
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12
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Structural basis of the substrate preference towards CMP for a thymidylate synthase MilA involved in mildiomycin biosynthesis. Sci Rep 2016; 6:39675. [PMID: 28000775 PMCID: PMC5175136 DOI: 10.1038/srep39675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/25/2016] [Indexed: 11/08/2022] Open
Abstract
Modified pyrimidine monophosphates such as methyl dCMP (mdCMP), hydroxymethyl dUMP (hmdUMP) and hmdCMP in some phages are synthesized by a large group of enzymes termed as thymidylate synthases (TS). Thymidylate is a nucleotide required for DNA synthesis and thus TS is an important drug target. In the biosynthetic pathway of the nucleoside fungicide mildiomycin isolated from Streptomyces rimofaciens ZJU5119, a cytidylate (CMP) hydroxymethylase, MilA, catalyzes the conversion of CMP into 5′-hydroxymethyl CMP (hmCMP) with an efficiency (kcat/KM) of 5-fold faster than for deoxycytidylate (dCMP). MilA is thus the first enzyme of the TS superfamily preferring CMP to dCMP. Here, we determined the crystal structures of MilA and its complexes with various substrates including CMP, dCMP and hmCMP. Comparing these structures to those of dCMP hydroxymethylase (CH) from T4 phage and TS from Escherichia coli revealed that two residues in the active site of CH and TS, a serine and an arginine, are respectively replaced by an alanine and a lysine, Ala176 and Lys133, in MilA. Mutation of A176S/K133R of MilA resulted in a reversal of substrate preference from CMP to dCMP. This is the first study reporting the evolution of the conserved TS in substrate selection from DNA metabolism to secondary nucleoside biosynthesis.
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13
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Malhotra S, Karanicolas J. When Does Chemical Elaboration Induce a Ligand To Change Its Binding Mode? J Med Chem 2016; 60:128-145. [PMID: 27982595 DOI: 10.1021/acs.jmedchem.6b00725] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Traditional hit-to-lead optimization assumes that upon elaboration of chemical structure, the ligand retains its binding mode relative to the receptor. Here, we build a large-scale collection of related ligand pairs solved in complex with the same protein partner: we find that for 41 of 297 pairs (14%), the binding mode changes upon elaboration of the smaller ligand. While certain ligand physiochemical properties predispose changes in binding mode, particularly those properties that define fragments, simple structure-based modeling proves far more effective for identifying substitutions that alter the binding mode. Some ligand pairs change binding mode because the added substituent would irreconcilably conflict with the receptor in the original pose, whereas others change because the added substituent enables new, stronger interactions that are available only in a different pose. Scaffolds that can engage their target using alternate poses may enable productive structure-based optimization along multiple divergent pathways.
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Affiliation(s)
- Shipra Malhotra
- Program in Molecular Therapeutics, Fox Chase Cancer Center , 333 Cottman Avenue, Philadelphia, Pennsylvania 19111, United States
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center , 333 Cottman Avenue, Philadelphia, Pennsylvania 19111, United States
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14
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Sapienza PJ, Lee AL. Widespread Perturbation of Function, Structure, and Dynamics by a Conservative Single-Atom Substitution in Thymidylate Synthase. Biochemistry 2016; 55:5702-5713. [PMID: 27649373 DOI: 10.1021/acs.biochem.6b00838] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thymidylate synthase (TSase) is responsible for synthesizing the sole de novo source of dTMP in all organisms. TSase is a drug target, and as such, it has been well studied in terms of both structure and reaction mechanism. Cysteine 146 in Escherichia coli TSase is universally conserved because it serves as the nucleophile in the enzyme mechanism. Here we use the C146S mutation to probe the role of the sulfur atom in early events in the catalytic cycle beyond serving as the nucleophile. Surprisingly, the single-atom substitution severely decreases substrate binding affinity, and the unfavorable ΔΔG°bind is comprised of roughly equal enthalpic and entropic components at 25 °C. Chemical shifts in the free and dUMP-bound states show the mutation causes perturbations throughout TSase, including regions important for complex stability, in agreement with a less favorable enthalpy change. We measured the nuclear magnetic resonance methyl symmetry axis order parameter (S2axis), a proxy for conformational entropy, for TSase at all vertices of the dUMP binding/C146S mutation thermodynamic cycle and found that the calculated TΔΔS°conf is similar in sign and magnitude to the calorimetric TΔΔS°. Further, we ascribed minor resonances in wild-type-dUMP spectra to a state with a covalent bond between Sγ of C146 and C6 of dUMP and find S2axis values are unaffected by covalent bond formation, indicating this reaction step is neutral with respect to ΔS°conf. Lastly, the C146S mutation allowed us to measure cofactor analog binding by isothermal titration calorimetry without the confounding heat signature of covalent bond formation. Raltitrexed binds free and singly bound TSase with similar affinities, yet the two binding events have different enthalpy changes, providing further evidence of communication between the two active sites.
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Affiliation(s)
- Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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15
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Kavanagh ME, Gray JL, Gilbert SH, Coyne AG, McLean KJ, Davis HJ, Munro AW, Abell C. Substrate Fragmentation for the Design of M. tuberculosis CYP121 Inhibitors. ChemMedChem 2016; 11:1924-35. [PMID: 27432475 PMCID: PMC5026067 DOI: 10.1002/cmdc.201600248] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 06/24/2016] [Indexed: 11/11/2022]
Abstract
The cyclo-dipeptide substrates of the essential M. tuberculosis (Mtb) enzyme CYP121 were deconstructed into their component fragments and screened against the enzyme. A number of hits were identified, one of which exhibited an unexpected inhibitor-like binding mode. The inhibitory pharmacophore was elucidated, and fragment binding affinity was rapidly improved by synthetic elaboration guided by the structures of CYP121 substrates. The resulting inhibitors have low micromolar affinity, good predicted physicochemical properties and selectivity for CYP121 over other Mtb P450s. Spectroscopic characterisation of the inhibitors' binding mode provides insight into the effect of weak nitrogen-donor ligands on the P450 heme, an improved understanding of factors governing CYP121-ligand recognition and speculation into the biological role of the enzyme for Mtb.
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Affiliation(s)
- Madeline E Kavanagh
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Janine L Gray
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Sophie H Gilbert
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Anthony G Coyne
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Kirsty J McLean
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of LifeSciences, The University of Manchester, Manchester, M1 7DN, UK
| | - Holly J Davis
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Andrew W Munro
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of LifeSciences, The University of Manchester, Manchester, M1 7DN, UK
| | - Chris Abell
- Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
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16
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Non-native ligands define the active site of Pennisetum glaucum (L.) R. Br dehydroascorbate reductase. Biochem Biophys Res Commun 2016; 473:1152-1157. [PMID: 27067046 DOI: 10.1016/j.bbrc.2016.04.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/07/2016] [Indexed: 11/21/2022]
Abstract
Dehydroascorbate reductase (DHAR), a member of the glutathione-S-transferase (GST) family, reduces dehydroascorbate (DHA) to ascorbate (AsA; Vitamin-C) in a glutathione (GSH)-dependent manner and in doing so, replenishes the critical AsA pool of the cell. To understand the enzyme mechanism in detail, we determined the crystal structure of a plant DHAR from Pennisetum glaucum (PgDHAR) using Iodide-Single Anomalous Dispersion (SAD) and Molecular replacement methods, in two different space groups. Here, we show PgDHAR in complex with two non-native ligands, viz. an acetate bound at the G-site, which resembles the γ-carboxyl moiety of GSH, and a glycerol at the H-site, which shares the backbone of AsA. We also show that, in the absence of bound native substrates, these non-native ligands help define the critical 'hook points' in the DHAR enzyme active site. Further, our data suggest that these non-native ligands can act as the logical bootstrapping points for iterative design of inhibitors/analogs for DHARs.
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17
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Kavanagh ME, Coyne AG, McLean KJ, James GG, Levy CW, Marino LB, de Carvalho LPS, Chan DSH, Hudson SA, Surade S, Leys D, Munro AW, Abell C. Fragment-Based Approaches to the Development of Mycobacterium tuberculosis CYP121 Inhibitors. J Med Chem 2016; 59:3272-302. [PMID: 27002486 PMCID: PMC4835159 DOI: 10.1021/acs.jmedchem.6b00007] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The essential enzyme CYP121 is a target for drug development against antibiotic resistant strains of Mycobacterium tuberculosis. A triazol-1-yl phenol fragment 1 was identified to bind to CYP121 using a cascade of biophysical assays. Synthetic merging and optimization of 1 produced a 100-fold improvement in binding affinity, yielding lead compound 2 (KD = 15 μM). Deconstruction of 2 into its component retrofragments allowed the group efficiency of structural motifs to be assessed, the identification of more LE scaffolds for optimization and highlighted binding affinity hotspots. Structure-guided addition of a metal-binding pharmacophore onto LE retrofragment scaffolds produced low nanomolar (KD = 15 nM) CYP121 ligands. Elaboration of these compounds to target binding hotspots in the distal active site afforded compounds with excellent selectivity against human drug-metabolizing P450s. Analysis of the factors governing ligand potency and selectivity using X-ray crystallography, UV-vis spectroscopy, and native mass spectrometry provides insight for subsequent drug development.
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Affiliation(s)
- Madeline E Kavanagh
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
| | - Anthony G Coyne
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
| | - Kirsty J McLean
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester , 131 Princess Street, Manchester M1 7DN, U.K
| | - Guy G James
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
| | - Colin W Levy
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester , 131 Princess Street, Manchester M1 7DN, U.K
| | - Leonardo B Marino
- Laboratory of Mycobacterial Metabolism and Antibiotic Research, Francis Crick Institute, The Mill Hill Laboratory , London NW7 1AA, U.K.,School of Pharmaceutical Sciences, São Paulo State University (UNESP) , 4801-902 Araraquara, SP, Brazil
| | - Luiz Pedro S de Carvalho
- Laboratory of Mycobacterial Metabolism and Antibiotic Research, Francis Crick Institute, The Mill Hill Laboratory , London NW7 1AA, U.K
| | - Daniel S H Chan
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
| | - Sean A Hudson
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
| | - Sachin Surade
- Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA U.K
| | - David Leys
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester , 131 Princess Street, Manchester M1 7DN, U.K
| | - Andrew W Munro
- Centre for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester , 131 Princess Street, Manchester M1 7DN, U.K
| | - Chris Abell
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, U.K
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18
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Sapienza PJ, Falk BT, Lee AL. Bacterial Thymidylate Synthase Binds Two Molecules of Substrate and Cofactor without Cooperativity. J Am Chem Soc 2015; 137:14260-3. [PMID: 26517288 DOI: 10.1021/jacs.5b10128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Thymidylate synthase (TSase) is a clinically important enzyme because it catalyzes synthesis of the sole de novo source of deoxy-thymidylate. Without this enzyme, cells die a "thymineless death" since they are starved of a crucial DNA synthesis precursor. As a drug target, TSase is well studied in terms of its structure and reaction mechanism. An interesting mechanistic feature of dimeric TSase is that it is "half-the-sites reactive", which is a form of negative cooperativity. Yet, the basis for this is not well-understood. Some experiments point to cooperativity at the binding steps of the reaction cycle as being responsible for the phenomenon, but the literature contains conflicting reports. Here we use ITC and NMR to resolve these inconsistencies. This first detailed thermodynamic dissection of multisite binding of dUMP to E. coli TSase shows the nucleotide binds to the free and singly bound forms of the enzyme with nearly equal affinity over a broad range of temperatures and in multiple buffers. While small but significant differences in ΔC°P for the two binding events show that the active sites are not formally equivalent, there is little-to-no allostery at the level of ΔG°bind. In addition NMR titration data reveal that there is minor intersubunit cooperativity in formation of a ternary complex with the mechanism based inhibitor, 5F-dUMP, and cofactor. Taken together, the data show that functional communication between subunits is minimal for both binding steps of the reaction coordinate.
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Affiliation(s)
- Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy and ‡Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Bradley T Falk
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy and ‡Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy and ‡Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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19
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Anderson DW, McKeown AN, Thornton JW. Intermolecular epistasis shaped the function and evolution of an ancient transcription factor and its DNA binding sites. eLife 2015; 4:e07864. [PMID: 26076233 PMCID: PMC4500092 DOI: 10.7554/elife.07864] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/13/2015] [Indexed: 02/07/2023] Open
Abstract
Complexes of specifically interacting molecules, such as transcription factor proteins (TFs) and the DNA response elements (REs) they recognize, control most biological processes, but little is known concerning the functional and evolutionary effects of epistatic interactions across molecular interfaces. We experimentally characterized all combinations of genotypes in the joint protein-DNA sequence space defined by an historical transition in TF-RE specificity that occurred some 500 million years ago in the DNA-binding domain of an ancient steroid hormone receptor. We found that rampant epistasis within and between the two molecules was essential to specific TF-RE recognition and to the evolution of a novel TF-RE complex with unique derived specificity. Permissive and restrictive epistatic mutations across the TF-RE interface opened and closed potential evolutionary paths accessible by the other, making the evolution of each molecule contingent on its partner's history and allowing a molecular complex with novel specificity to evolve.
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Affiliation(s)
- Dave W Anderson
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Alesia N McKeown
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Joseph W Thornton
- Department of Ecology and Evolution, University of Chicago, Chicago, United States
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20
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Barelier S, Cummings J, Rauwerdink AM, Hitchcock DS, Farelli JD, Almo SC, Raushel FM, Allen KN, Shoichet BK. Substrate deconstruction and the nonadditivity of enzyme recognition. J Am Chem Soc 2014; 136:7374-82. [PMID: 24791931 PMCID: PMC4046767 DOI: 10.1021/ja501354q] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Indexed: 12/15/2022]
Abstract
Predicting substrates for enzymes of unknown function is a major postgenomic challenge. Substrate discovery, like inhibitor discovery, is constrained by our ability to explore chemotypes; it would be expanded by orders of magnitude if reactive sites could be probed with fragments rather than fully elaborated substrates, as is done for inhibitor discovery. To explore the feasibility of this approach, substrates of six enzymes from three different superfamilies were deconstructed into 41 overlapping fragments that were tested for activity or binding. Surprisingly, even those fragments containing the key reactive group had little activity, and most fragments did not bind measurably, until they captured most of the substrate features. Removing a single atom from a recognized substrate could often reduce catalytic recognition by 6 log-orders. To explore recognition at atomic resolution, the structures of three fragment complexes of the β-lactamase substrate cephalothin were determined by X-ray crystallography. Substrate discovery may be difficult to reduce to the fragment level, with implications for function discovery and for the tolerance of enzymes to metabolite promiscuity. Pragmatically, this study supports the development of libraries of fully elaborated metabolites as probes for enzyme function, which currently do not exist.
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Affiliation(s)
- Sarah Barelier
- Department
of Pharmaceutical Chemistry, University
of California - San Francisco, 1700 Fourth Street, Byers Hall, San Francisco, California 94158, United States
| | - Jennifer
A. Cummings
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Alissa M. Rauwerdink
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Daniel S. Hitchcock
- Department
of Biochemistry and Biophysics, Texas A&M
University, College Station, Texas, United States
| | - Jeremiah D. Farelli
- Department
of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215-2521, United States
| | - Steven C. Almo
- Department
of Biochemistry, Albert Einstein College
of Medicine, New York, New York 10461, United
States
| | - Frank M. Raushel
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Department
of Biochemistry and Biophysics, Texas A&M
University, College Station, Texas, United States
| | - Karen N. Allen
- Department
of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215-2521, United States
| | - Brian K. Shoichet
- Department
of Pharmaceutical Chemistry, University
of California - San Francisco, 1700 Fourth Street, Byers Hall, San Francisco, California 94158, United States
- Faculty of
Pharmacy, University of Toronto, Donnelly Centre Suite 604, 160 College
Street, Toronto, Ontario, Canada, M5S 3E1
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21
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Hudson SA, Mashalidis EH, Bender A, McLean KJ, Munro AW, Abell C. Biofragments: an approach towards predicting protein function using biologically related fragments and its application to Mycobacterium tuberculosis CYP126. Chembiochem 2014; 15:549-55. [PMID: 24677424 PMCID: PMC4159592 DOI: 10.1002/cbic.201300697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Indexed: 11/21/2022]
Abstract
We present a novel fragment-based approach that tackles some of the challenges for chemical biology of predicting protein function. The general approach, which we have termed biofragments, comprises two key stages. First, a biologically relevant fragment library (biofragment library) can be designed and constructed from known sets of substrate-like ligands for a protein class of interest. Second, the library can be screened for binding to a novel putative ligand-binding protein from the same or similar class, and the characterization of hits provides insight into the basis of ligand recognition, selectivity, and function at the substrate level. As a proof-of-concept, we applied the biofragments approach to the functionally uncharacterized Mycobacterium tuberculosis (Mtb) cytochrome P450 isoform, CYP126. This led to the development of a tailored CYP biofragment library with notable 3D characteristics and a significantly higher screening hit rate (14%) than standard drug-like fragment libraries screened previously against Mtb CYP121 and 125 (4% and 1%, respectively). Biofragment hits were identified that make both substrate-like type-I and inhibitor-like type-II interactions with CYP126. A chemical-fingerprint-based substrate model was built from the hits and used to search a virtual TB metabolome, which led to the discovery that CYP126 has a strong preference for the recognition of aromatics and substrate-like type-I binding of chlorophenol moieties within the active site near the heme. Future catalytic analyses will be focused on assessing CYP126 for potential substrate oxidative dehalogenation.
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Affiliation(s)
- Sean A Hudson
- Department of Chemistry, University of CambridgeLensfield Road, Cambridge, CB2 1EW (UK) E-mail: Homepage: http://www-abell.ch.cam.ac.uk/
| | - Ellene H Mashalidis
- Department of Chemistry, University of CambridgeLensfield Road, Cambridge, CB2 1EW (UK) E-mail: Homepage: http://www-abell.ch.cam.ac.uk/
| | - Andreas Bender
- Unilever Centre for Molecular Informatics Department of Chemistry, University of CambridgeLensfield Road, Cambridge, CB2 1EW (UK)
| | - Kirsty J McLean
- Manchester Institute of Biotechnology, University of Manchester131 Princess Street, Manchester, M1 7DN (UK)
| | - Andrew W Munro
- Manchester Institute of Biotechnology, University of Manchester131 Princess Street, Manchester, M1 7DN (UK)
| | - Chris Abell
- Department of Chemistry, University of CambridgeLensfield Road, Cambridge, CB2 1EW (UK) E-mail: Homepage: http://www-abell.ch.cam.ac.uk/
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22
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Van Molle I, Thomann A, Buckley DL, So EC, Lang S, Crews CM, Ciulli A. Dissecting fragment-based lead discovery at the von Hippel-Lindau protein:hypoxia inducible factor 1α protein-protein interface. ACTA ACUST UNITED AC 2013; 19:1300-12. [PMID: 23102223 DOI: 10.1016/j.chembiol.2012.08.015] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/10/2012] [Accepted: 08/16/2012] [Indexed: 01/06/2023]
Abstract
Fragment screening is widely used to identify attractive starting points for drug design. However, its potential and limitations to assess the tractability of often challenging protein:protein interfaces have been underexplored. Here, we address this question by means of a systematic deconstruction of lead-like inhibitors of the pVHL:HIF-1α interaction into their component fragments. Using biophysical techniques commonly employed for screening, we could only detect binding of fragments that violate the Rule of Three, are more complex than those typically screened against classical druggable targets, and occupy two adjacent binding subsites at the interface rather than just one. Analyses based on ligand and group lipophilicity efficiency of anchored fragments were applied to dissect the individual subsites and probe for binding hot spots. The implications of our findings for targeting protein interfaces by fragment-based approaches are discussed.
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Affiliation(s)
- Inge Van Molle
- Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
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23
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Abstract
Fragment-based drug discovery (FBDD) concerns the screening of low-molecular weight compounds against macromolecular targets of clinical relevance. These compounds act as starting points for the development of drugs. FBDD has evolved and grown in popularity over the past 15 years. In this paper, the rationale and technology behind the use of X-ray crystallography in fragment based screening (FBS) will be described, including fragment library design and use of synchrotron radiation and robotics for high-throughput X-ray data collection. Some recent uses of crystallography in FBS will be described in detail, including interrogation of the drug targets β-secretase, phenylethanolamine N-methyltransferase, phosphodiesterase 4A and Hsp90. These examples provide illustrations of projects where crystallography is straightforward or difficult, and where other screening methods can help overcome the limitations of crystallography necessitated by diffraction quality.
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Affiliation(s)
- Zorik Chilingaryan
- School of Chemistry, University of Wollongong, Northfields Ave, Wollongong 2522, NSW, Australia.
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24
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Sturm N, Desaphy J, Quinn RJ, Rognan D, Kellenberger E. Structural insights into the molecular basis of the ligand promiscuity. J Chem Inf Model 2012; 52:2410-21. [PMID: 22920885 DOI: 10.1021/ci300196g] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Selectivity is a key factor in drug development. In this paper, we questioned the Protein Data Bank to better understand the reasons for the promiscuity of bioactive compounds. We assembled a data set of >1000 pairs of three-dimensional structures of complexes between a "drug-like" ligand (as its physicochemical properties overlap that of approved drugs) and two distinct "druggable" protein targets (as their binding sites are likely to accommodate "drug-like" ligands). Studying the similarity between the ligand-binding sites in the different targets revealed that the lack of selectivity of a ligand can be due (i) to the fact that Nature has created the same binding pocket in different proteins, which do not necessarily have otherwise sequence or fold similarity, or (ii) to specific characteristics of the ligand itself. In particular, we demonstrated that many ligands can adapt to different protein environments by changing their conformation, by using different chemical moieties to anchor to different targets, or by adopting unusual extreme binding modes (e.g., only apolar contact between the ligand and the protein, even though polar groups are present on the ligand or at the protein surface). Lastly, we provided new elements in support to the recent studies which suggest that the promiscuity of a ligand might be inferred from its molecular complexity.
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Affiliation(s)
- Noé Sturm
- UMR 7200 CNRS/Université de Strasbourg, MEDALIS Drug Discovery Center, 74 Route du Rhin, 67401 Illkirch, France
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25
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Behnen J, Köster H, Neudert G, Craan T, Heine A, Klebe G. Experimental and computational active site mapping as a starting point to fragment-based lead discovery. ChemMedChem 2011; 7:248-61. [PMID: 22213702 DOI: 10.1002/cmdc.201100490] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 11/23/2011] [Indexed: 11/06/2022]
Abstract
Small highly soluble probe molecules such as aniline, urea, N-methylurea, 2-bromoacetate, 1,2-propanediol, nitrous oxide, benzamidine, and phenol were soaked into crystals of various proteins to map their binding pockets and to detect hot spots of binding with respect to hydrophobic and hydrophilic properties. The selected probe molecules were first tested at the zinc protease thermolysin. They were then applied to a wider range of proteins such as protein kinase A, D-xylose isomerase, 4-diphosphocytidyl-2C-methyl-D-erythritol synthase, endothiapepsin, and secreted aspartic protease 2. The crystal structures obtained clearly show that the probe molecules populate the protein binding pockets in an ordered fashion. The thus characterized, experimentally observed hot spots of binding were subjected to computational active site mapping using HotspotsX. This approach uses knowledge-based pair potentials to detect favorable binding positions for various atom types. Good agreement between the in silico hot spot predictions and the experimentally observed positions of the polar hydrogen bond forming functional groups and hydrophobic portions was obtained. Finally, we compared the observed poses of the small-molecule probes with those of much larger structurally related ligands. They coincide remarkably well with the larger ligands, considering their spatial orientation and the experienced interaction patterns. This observation confirms the fundamental hypothesis of fragment-based lead discovery: that binding poses, even of very small molecular probes, do not significantly deviate or move once a ligand is grown further into the binding site. This underscores the fact that these probes populate given hot spots and can be regarded as relevant seeds for further design.
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Affiliation(s)
- Jürgen Behnen
- Department of Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, 35032 Marburg, Germany
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26
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Computational medicinal chemistry in fragment-based drug discovery: what, how and when. Future Med Chem 2011; 3:95-134. [DOI: 10.4155/fmc.10.277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The use of fragment-based drug discovery (FBDD) has increased in the last decade due to the encouraging results obtained to date. In this scenario, computational approaches, together with experimental information, play an important role to guide and speed up the process. By default, FBDD is generally considered as a constructive approach. However, such additive behavior is not always present, therefore, simple fragment maturation will not always deliver the expected results. In this review, computational approaches utilized in FBDD are reported together with real case studies, where applicability domains are exemplified, in order to analyze them, and then, maximize their performance and reliability. Thus, a proper use of these computational tools can minimize misleading conclusions, keeping the credit on FBDD strategy, as well as achieve higher impact in the drug-discovery process. FBDD goes one step beyond a simple constructive approach. A broad set of computational tools: docking, R group quantitative structure–activity relationship, fragmentation tools, fragments management tools, patents analysis and fragment-hopping, for example, can be utilized in FBDD, providing a clear positive impact if they are utilized in the proper scenario – what, how and when. An initial assessment of additive/non-additive behavior is a critical point to define the most convenient approach for fragments elaboration.
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27
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Fusaro M, Jurkiewicz A, Jarmuła A, Leś A, Rode W. Hypothesis of a proton switch in QM/MM modelling of interaction of dUMP analogues with thymidylate synthase. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927022.2010.502938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Zangi R, Arrieta A, Cossío FP. Mechanism of DNA methylation: the double role of DNA as a substrate and as a cofactor. J Mol Biol 2010; 400:632-44. [PMID: 20471982 DOI: 10.1016/j.jmb.2010.05.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 04/29/2010] [Accepted: 05/09/2010] [Indexed: 11/24/2022]
Abstract
Methylation of cytosine residues in the DNA is one of the most important epigenetic marks central to the control of differential expression of genes. We perform quantum mechanical calculations to investigate the catalytic mechanism of the bacterial HhaI DNA methyltransferase. We find that the enzyme nucleophile, Cys81, can attack C6 of cytosine only after it is deprotonated by the DNA phosphate group, a reaction facilitated by a bridging water molecule. This finding, which indicates that the DNA acts as both the substrate and the cofactor, can explain the total loss of activity observed in an analogous enzyme, thymidylate synthase, when the phosphate group of the substrate was removed. Furthermore, our results displaying the inability of the phosphate group to deprotonate the side chain of serine is in agreement with the total, or the large extent of, inactivity observed for the C81S mutant. In contrast to results from previous calculations, we find that the active site conserved residues, Glu119, Arg163, and Arg165, are crucial for catalysis. In addition, the enzyme-DNA adduct formation and the methyl transfer from the cofactor S-adenosyl-L-methionine are not concerted but proceed via stepwise mechanism. In many of the different steps of this methylation reaction, the transfer of a proton is found to be necessary. To render these processes possible, we find that several water molecules, found in the crystal structure, play an important role, acting as a bridge between the donating and accepting proton groups.
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Affiliation(s)
- Ronen Zangi
- Department of Organic Chemistry I, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018 San Sebastian, Spain.
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29
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Barelier S, Pons J, Marcillat O, Lancelin JM, Krimm I. Fragment-based deconstruction of Bcl-xL inhibitors. J Med Chem 2010; 53:2577-88. [PMID: 20192224 DOI: 10.1021/jm100009z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fragment-based drug design consists of screening low-molecular-weight compounds in order to identify low-affinity ligands that are then modified or linked to yield potent inhibitors. The method thus attempts to build bioactive molecules in a modular way and relies on the hypothesis that the fragment binding mode will be conserved upon elaboration of the active molecule. If the inverse process is considered, do the fragments resulting from the deconstruction of high-affinity inhibitors recapitulate their binding mode in the large molecule? Few studies deal with this issue. Here, we report the analysis of 22 fragments resulting from the dissection of 9 inhibitors of the antiapoptotic protein Bcl-x(L). To determine if the fragments retained affinity toward the protein and identify their binding site, ligand-observed and protein-observed NMR experiments were used. The analysis of the fragments behavior illustrates the complexity of low-affinity protein-ligand interactions involved in the fragment-based construction of bioactive molecules.
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Affiliation(s)
- Sarah Barelier
- Laboratoire des Sciences Analytiques, UMR CNRS 5180, Universite de Lyon, Universite Claude Bernard, Lyon 1, Bat ESCPE Lyon, Domaine Scientifique de la Doua, 69100 Villeurbanne, France
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30
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Assessment of Additive/Nonadditive Effects in Structure−Activity Relationships: Implications for Iterative Drug Design. J Med Chem 2008; 51:7552-62. [DOI: 10.1021/jm801070q] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Martucci WE, Vargo MA, Anderson KS. Explaining an unusually fast parasitic enzyme: folate tail-binding residues dictate substrate positioning and catalysis in Cryptosporidium hominis thymidylate synthase. Biochemistry 2008; 47:8902-11. [PMID: 18672899 DOI: 10.1021/bi800466z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The essential enzyme TS-DHFR from Cryptosporidium hominis undergoes an unusually rapid rate of catalysis at the conserved TS domain, facilitated by two nonconserved residues, Ala287 and Ser290, in the folate tail-binding region. Mutation of these two residues to their conserved counterparts drastically affects multiple steps of the TS catalytic cycle. We have determined the crystal structures of all three mutants (A287F, S290G, and A287F/S290G) in complex with active site ligands dUMP and CB3717. The structural data show two effects of the mutations: an increased distance between the ligands in the active site and increased flexibility of the folate ligand in the partially open enzyme state that precedes conformational change to the active catalytic state. The latter effect is able to be rescued by the mutants containing the A287F mutation. In addition, the conserved water network of TS is altered in each of the mutants. The structural results point to a role of the folate tail-binding residues in closely positioning ChTS ligands and restricting ligand flexibility in the partially open state to allow for a rapid transition to the active closed state and enhanced rate of catalysis. These results provide an explanation on how folate tail-binding residues at one end of the active site affect long-range interactions throughout the TS active site and validate these residues as targets for species-specific drug design.
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Affiliation(s)
- W Edward Martucci
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
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32
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Jarmuła A, Dowierciał A, Rode W. A molecular modeling study of the interaction of 2'-fluoro-substituted analogues of dUMP/FdUMP with thymidylate synthase. Bioorg Med Chem Lett 2008; 18:2701-8. [PMID: 18362071 DOI: 10.1016/j.bmcl.2008.03.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 03/03/2008] [Accepted: 03/06/2008] [Indexed: 10/22/2022]
Abstract
Molecular dynamics simulations and free energy calculations are presented, exploring previously described experimentally studied interactions of a series of 2'-fluoro-substituted dUMP/FdUMP analogues with thymidylate synthase (TS). The results show the inhibitory behaviors of 2'-F-ara-UMP, 2',2''-diF-dUMP and 2',5-diF-ara-UMP to be dependent upon the binding positions and orientations adopted by the molecules of these compounds in the active site of TS. The binding mode of 2',5-diF-ara-UMP suggests a novel role of the active site residue Trp 80, stabilizing through hydrophobic stacking the binding position of the pyrimidine ring in 2',5-diF-ara-UMP.
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Affiliation(s)
- Adam Jarmuła
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warszawa, Poland.
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33
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Arvizu-Flores AA, Sugich-Miranda R, Arreola R, Garcia-Orozco KD, Velazquez-Contreras EF, Montfort WR, Maley F, Sotelo-Mundo RR. Role of an invariant lysine residue in folate binding on Escherichia coli thymidylate synthase: calorimetric and crystallographic analysis of the K48Q mutant. Int J Biochem Cell Biol 2008; 40:2206-17. [PMID: 18403248 PMCID: PMC2533807 DOI: 10.1016/j.biocel.2008.02.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 02/20/2008] [Accepted: 02/27/2008] [Indexed: 11/25/2022]
Abstract
Thymidylate synthase (TS) catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) using methylene tetrahydrofolate (CH(2)THF) as cofactor, the glutamate tail of which forms a water-mediated hydrogen bond with an invariant lysine residue of this enzyme. To understand the role of this interaction, we studied the K48Q mutant of Escherichia coli TS using structural and biophysical methods. The k(cat) of the K48Q mutant was 430-fold lower than wild-type TS in activity, while the K(m) for the (R)-stereoisomer of CH(2)THF was 300 microM, about 30-fold larger than K(m) from the wild-type TS. Affinity constants were determined using isothermal titration calorimetry, which showed that binding was reduced by one order of magnitude for folate-like TS inhibitors, such as propargyl-dideazafolate (PDDF) or compounds that distort the TS active site like BW1843U89 (U89). The crystal structure of the K48Q-dUMP complex revealed that dUMP binding is not impaired in the mutant, and that U89 in a ternary complex of K48Q-nucleotide-U89 was bound in the active site with subtle differences relative to comparable wild-type complexes. PDDF failed to form ternary complexes with K48Q and dUMP. Thermodynamic data correlated with the structural determinations, since PDDF binding was dominated by enthalpic effects while U89 had an important entropic component. In conclusion, K48 is critical for catalysis since it leads to a productive CH(2)THF binding, while mutation at this residue does not affect much the binding of inhibitors that do not make contact with this group.
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Affiliation(s)
- Aldo A. Arvizu-Flores
- Aquatic Molecular Biology Laboratory, Centro de Investigación en Alimentación y Desarrollo, A.C. Hermosillo, Sonora, México 83000
| | - Rocio Sugich-Miranda
- Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Hermosillo, Sonora, México
| | - Rodrigo Arreola
- Departamento de Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México DF 04510
| | - Karina D. Garcia-Orozco
- Aquatic Molecular Biology Laboratory, Centro de Investigación en Alimentación y Desarrollo, A.C. Hermosillo, Sonora, México 83000
| | | | - William R. Montfort
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721, USA
| | - Frank Maley
- Wadsworth Center, New York State Department of Health, Albany, New York, 12201, USA
| | - Rogerio R. Sotelo-Mundo
- Aquatic Molecular Biology Laboratory, Centro de Investigación en Alimentación y Desarrollo, A.C. Hermosillo, Sonora, México 83000
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Ciulli A, Abell C. Fragment-based approaches to enzyme inhibition. Curr Opin Biotechnol 2007; 18:489-96. [PMID: 17959370 DOI: 10.1016/j.copbio.2007.09.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 09/07/2007] [Accepted: 09/12/2007] [Indexed: 01/28/2023]
Abstract
Fragment-based approaches have provided a new paradigm for small-molecule drug discovery. The methodology is complementary to high-throughput screening approaches, starting from fragments of low molecular complexity and high ligand efficiency, and building up to more potent inhibitors. The approach, which depends heavily on a number of biophysical techniques, is now being taken up by more groups in both industry and academia. This article describes key aspects of the process and highlights recent developments and applications.
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Affiliation(s)
- Alessio Ciulli
- University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
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36
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Jarmuła A, Cieplak P, Krygowski TM, Rode W. The effect of 5-substitution in the pyrimidine ring of dUMP on the interaction with thymidylate synthase: molecular modeling and QSAR. Bioorg Med Chem 2007; 15:2346-58. [PMID: 17275316 DOI: 10.1016/j.bmc.2007.01.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 12/24/2006] [Accepted: 01/17/2007] [Indexed: 11/20/2022]
Abstract
Thymidylate synthase (TS) is a target enzyme for a number of anticancer agents including the 5-fluorouracil metabolite, FdUMP. The present paper reports on molecular modeling studies of the effect of substitution at C(5) position in the pyrimidine ring of the TS substrate, dUMP, on the binding affinity for the enzyme. The results of molecular dynamics simulations show that the binding of C(5) analogues of dUMP to TS in the binary complexes does not undergo changes, unless a substituent with a large steric effect, such as the propyl group, is involved. On the other hand, apparent differences in the binding of the TS cofactor, resulting from varying substitution at dUMP C(5), are observed in the modeled structures of the ternary complexes of TS. These binding characteristics are supplemented with a classical QSAR model quantifying the relation between the affinity for TS and the substituent electronic and steric effects of C(5) analogues of dUMP. Based on the findings from the present work, the perspectives for finding promising new C(5) analogues of dUMP as potential agents targeted against TS are discussed.
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Affiliation(s)
- Adam Jarmuła
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland.
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37
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Babaoglu K, Shoichet BK. Deconstructing fragment-based inhibitor discovery. Nat Chem Biol 2006; 2:720-3. [PMID: 17072304 DOI: 10.1038/nchembio831] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 08/30/2006] [Indexed: 01/03/2023]
Abstract
Fragment-based screens test multiple low-molecular weight molecules for binding to a target. Fragments often bind with low affinities but typically have better ligand efficiencies (DeltaG(bind)/heavy atom count) than traditional screening hits. This efficiency, combined with accompanying atomic-resolution structures, has made fragments popular starting points for drug discovery programs. Fragment-based design adopts a constructive strategy: affinity is enhanced either by cycles of functional-group addition or by joining two independent fragments together. The final inhibitor is expected to adopt the same geometry as the original fragment hit. Here we consider whether the inverse, deconstructive logic also applies--can one always parse a higher-affinity inhibitor into fragments that recapitulate the binding geometry of the larger molecule? Cocrystal structures of fragments deconstructed from a known beta-lactamase inhibitor suggest that this is not always the case.
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38
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Ciulli A, Williams G, Smith AG, Blundell TL, Abell C. Probing hot spots at protein-ligand binding sites: a fragment-based approach using biophysical methods. J Med Chem 2006; 49:4992-5000. [PMID: 16884311 DOI: 10.1021/jm060490r] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mapping interactions at protein-ligand binding sites is an important aspect of understanding many biological reactions and a key part of drug design. In this paper, we have used a fragment-based approach to probe "hot spots" at the cofactor-binding site of a model dehydrogenase, Escherichia coli ketopantoate reductase. Our strategy involved the breaking down of NADPH (Kd = 300 nM) into smaller fragments and the biophysical characterization of their binding using WaterLOGSY NMR spectroscopy, isothermal titration calorimetry (ITC), and inhibition studies. The weak binding affinities of fragments were measured by direct ITC titrations under low c value conditions. The 2'-phosphate and the reduced nicotinamide groups were found to contribute a large part of the binding energy. A combination of ITC and site-directed mutagenesis enabled us to locate the fragments at separate hot spots on opposite ends of the cofactor-binding site. This study has identified structural determinants for cofactor recognition that represent a blueprint for future inhibitor design.
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Affiliation(s)
- Alessio Ciulli
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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39
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Newby Z, Lee TT, Morse RJ, Liu Y, Liu L, Venkatraman P, Santi DV, Finer-Moore JS, Stroud RM. The role of protein dynamics in thymidylate synthase catalysis: variants of conserved 2'-deoxyuridine 5'-monophosphate (dUMP)-binding Tyr-261. Biochemistry 2006; 45:7415-28. [PMID: 16768437 PMCID: PMC2556892 DOI: 10.1021/bi060152s] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The enzyme thymidylate synthase (TS) catalyzes the reductive methylation of 2'-deoxyuridine 5'-monophosphate (dUMP) to 2'-deoxythymidine 5'-monophosphate. Using kinetic and X-ray crystallography experiments, we have examined the role of the highly conserved Tyr-261 in the catalytic mechanism of TS. While Tyr-261 is distant from the site of methyl transfer, mutants at this position show a marked decrease in enzymatic activity. Given that Tyr-261 forms a hydrogen bond with the dUMP 3'-O, we hypothesized that this interaction would be important for substrate binding, orientation, and specificity. Our results, surprisingly, show that Tyr-261 contributes little to these features of the mechanism of TS. However, the residue is part of the structural core of closed ternary complexes of TS, and conservation of the size and shape of the Tyr side chain is essential for maintaining wild-type values of kcat/Km. Moderate increases in Km values for both the substrate and cofactor upon mutation of Tyr-261 arise mainly from destabilization of the active conformation of a loop containing a dUMP-binding arginine. Besides binding dUMP, this loop has a key role in stabilizing the closed conformation of the enzyme and in shielding the active site from the bulk solvent during catalysis. Changes to atomic vibrations in crystals of a ternary complex of Escherichia coli Tyr261Trp are associated with a greater than 2000-fold drop in kcat/Km. These results underline the important contribution of dynamics to catalysis in TS.
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Affiliation(s)
- Zachary Newby
- University of California at San Francisco, San Francisco, California 94143-0448, USA
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40
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Sotelo-Mundo RR, Changchien L, Maley F, Montfort WR. Crystal structures of thymidylate synthase mutant R166Q: structural basis for the nearly complete loss of catalytic activity. J Biochem Mol Toxicol 2006; 20:88-92. [PMID: 16615077 DOI: 10.1002/jbt.20122] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Thymidylate synthase (TS) catalyzes the folate-dependent methylation of deoxyuridine monophosphate (dUMP) to form thymidine monophosphate (dTMP). We have investigated the role of invariant arginine 166, one of four arginines that contact the dUMP phosphate, using site-directed mutagenesis, X-ray crystallography, and TS from Escherichia coli. The R166Q mutant was crystallized in the presence of dUMP and a structure determined to 2.9 A resolution, but neither the ligand nor the sulfate from the crystallization buffer was found in the active site. A second structure determined with crystals prepared in the presence of dUMP and the antifolate 10-propargyl-5,8-dideazafolate revealed that the inhibitor was bound in an extended, nonproductive conformation, partially occupying the nucleotide-binding site. A sulfate ion, rather than dUMP, was found in the nucleotide phosphate-binding site. Previous studies have shown that the substitution at three of the four arginines of the dUMP phosphate-binding site is permissive; however; for Arg166, all the mutations lead to a near-inactive mutant. The present structures of TS R166Q reveal that the phosphate-binding site is largely intact, but with a substantially reduced affinity for phosphate, despite the presence of the three remaining arginines. The position of Cys146, which initiates catalysis, is shifted in the mutant and resides in a position that interferes with the binding of the dUMP pyrimidine moiety.
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Affiliation(s)
- Rogerio R Sotelo-Mundo
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, AZ 85721, USA.
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41
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Rummey C, Nordhoff S, Thiemann M, Metz G. In silico fragment-based discovery of DPP-IV S1 pocket binders. Bioorg Med Chem Lett 2006; 16:1405-9. [PMID: 16321524 DOI: 10.1016/j.bmcl.2005.11.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Revised: 11/10/2005] [Accepted: 11/10/2005] [Indexed: 11/27/2022]
Abstract
Dipeptidyl peptidase IV is a clinically validated target for type-2 diabetes and belongs to a family of peptidases with a quite unique post-proline cleavage specificity. Known inhibitors contain a limited number of molecular anchors occupying the small prototypical S1 pocket. A virtual screening approach for such S1-binding fragments was carried out using FlexX docking to evaluate its potential to confirm known and find novel compounds. Several low molecular weight inhibitors exhibiting activities in the micromolar range could be identified as starting points for structure-based design.
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Affiliation(s)
- Christian Rummey
- Computational Discovery, Santhera Pharmaceuticals, Im Neuenheimer Feld 518-519, 69120 Heidelberg, Germany
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42
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Jackson M, Chopra S, Smiley RD, Maynord PO, Rosowsky A, London RE, Levy L, Kalman TI, Howell EE. Calorimetric studies of ligand binding in R67 dihydrofolate reductase. Biochemistry 2005; 44:12420-33. [PMID: 16156655 DOI: 10.1021/bi050881s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
R67 dihydrofolate reductase (DHFR) is a novel bacterial protein that possesses 222 symmetry and a single active site pore. Although the 222 symmetry implies that four symmetry-related binding sites must exist for each substrate as well as for each cofactor, various studies indicate only two molecules bind. Three possible combinations include two dihydrofolate molecules, two NADPH molecules, or one substrate plus one cofactor. The latter is the productive ternary complex. To explore the role of various ligand substituents during binding, numerous analogues, inhibitors, and fragments of NADPH and/or folate were used in both isothermal titration calorimetry (ITC) and K(i) studies. Not surprisingly, as the length of the molecule is shortened, affinity is lost, indicating that ligand connectivity is important in binding. The observed enthalpy change in ITC measurements arises from all components involved in the binding process, including proton uptake. As a buffer dependence for binding of folate was observed, this likely correlates with perturbation of the bound N3 pK(a), such that a neutral pteridine ring is preferred for pairwise interaction with the protein. Of interest, there is no enthalpic signal for binding of folate fragments such as dihydrobiopterin where the p-aminobenzoylglutamate tail has been removed, pointing to the tail as providing most of the enthalpic signal. For binding of NADPH and its analogues, the nicotinamide carboxamide is quite important. Differences between binary (binding of two identical ligands) and ternary complex formation are observed, indicating interligand pairing preferences. For example, while aminopterin and methotrexate both form binary complexes, albeit weakly, neither readily forms ternary complexes with the cofactor. These observations suggest a role for the O4 atom of folate in a pairing preference with NADPH, which ultimately facilitates catalysis.
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Affiliation(s)
- Michael Jackson
- Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, USA
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43
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Schüttelkopf AW, Hardy LW, Beverley SM, Hunter WN. Structures of Leishmania major pteridine reductase complexes reveal the active site features important for ligand binding and to guide inhibitor design. J Mol Biol 2005; 352:105-16. [PMID: 16055151 DOI: 10.1016/j.jmb.2005.06.076] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 06/29/2005] [Accepted: 06/30/2005] [Indexed: 11/23/2022]
Abstract
Pteridine reductase (PTR1) is an NADPH-dependent short-chain reductase found in parasitic trypanosomatid protozoans. The enzyme participates in the salvage of pterins and represents a target for the development of improved therapies for infections caused by these parasites. A series of crystallographic analyses of Leishmania major PTR1 are reported. Structures of the enzyme in a binary complex with the cofactor NADPH, and ternary complexes with cofactor and biopterin, 5,6-dihydrobiopterin, and 5,6,7,8-tetrahydrobiopterin reveal that PTR1 does not undergo any major conformational changes to accomplish binding and processing of substrates, and confirm that these molecules bind in a single orientation at the catalytic center suitable for two distinct reductions. Ternary complexes with cofactor and CB3717 and trimethoprim (TOP), potent inhibitors of thymidylate synthase and dihydrofolate reductase, respectively, have been characterized. The structure with CB3717 reveals that the quinazoline moiety binds in similar fashion to the pterin substrates/products and dominates interactions with the enzyme. In the complex with TOP, steric restrictions enforced on the trimethoxyphenyl substituent prevent the 2,4-diaminopyrimidine moiety from adopting the pterin mode of binding observed in dihydrofolate reductase, and explain the inhibition properties of a range of pyrimidine derivates. The molecular detail provided by these complex structures identifies the important interactions necessary to assist the structure-based development of novel enzyme inhibitors of potential therapeutic value.
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Affiliation(s)
- Alexander W Schüttelkopf
- Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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44
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Edgell DR, Stanger MJ, Belfort M. Coincidence of cleavage sites of intron endonuclease I-TevI and critical sequences of the host thymidylate synthase gene. J Mol Biol 2004; 343:1231-41. [PMID: 15491609 DOI: 10.1016/j.jmb.2004.09.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 08/25/2004] [Accepted: 09/02/2004] [Indexed: 12/01/2022]
Abstract
To maximize spread of their host intron or intein, many homing endonucleases recognize nucleotides that code for important and conserved amino acid residues of the target gene. Here, we examine the cleavage requirements for I-TevI, which binds a stretch of thymidylate synthase (TS) DNA that codes for functionally critical residues in the TS active site. Using an in vitro selection scheme, we identified two base-pairs in the I-TevI cleavage site region as important for cleavage efficiency. These were confirmed by comparison of I-TevI cleavage efficiencies on mutant and on wild-type substrates. We also showed that nicking of the bottom strand by I-TevI is not affected by mutation of residues surrounding the bottom-strand cleavage site, unlike other homing endonucleases. One of these two base-pairs is universally conserved in all TS sequences, and is identical with a previously identified cleavage determinant of I-BmoI, a related GIY-YIG endonuclease that binds a homologous stretch of TS-encoding DNA. The other base-pair is conserved only in a subset of TS genes that includes the I-TevI, but not the I-BmoI, target sequence. Both the I-TevI and I-BmoI cleavage site requirements correspond to functionally critical residues involved in an extensive hydrogen bond network within the TS active site. Remarkably, these cleavage requirements correlate with TS phylogeny in bacteria, suggesting that each endonuclease has individually adapted to efficiently cleave distinct TS substrates.
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Affiliation(s)
- David R Edgell
- Molecular Genetics Program, Wadsworth Center, New York State Department of Health, PO Box 22002, Albany, NY 12201-2002, USA.
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45
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Jarmuła A, Cieplak P, Leś A, Rode W. Relative free energies of binding to thymidylate synthase of 2- and/or 4-thio and/or 5-fluoro analogues of dUMP. J Comput Aided Mol Des 2004; 17:699-710. [PMID: 15068368 DOI: 10.1023/b:jcam.0000017377.07094.2e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Free energy perturbation calculations have been applied to evaluate the relative free energies of binding of 2'-deoxyuridine-5'-monophosphate (dUMP) and its 2- and/or 4-thio and/or 5-fluoro analogues to the wild-type E. coli thymidylate synthase (ecTS). The results accurately reproduce experimentally measured differences in the free energy of binding of dUMP versus 5-fluoro-dUMP to thymidylate synthase. They indicate that preferred binding of dUMP compared to 5-fluoro-dUMP in the binary complex is equally related to (i) more favorable electrostatic interactions of the dUMP molecule in the enzyme active site, and (ii) its less favorable solvation in the aqueous solution. The relative free energies of binding in the binary complex show moderate and qualitatively indistinguishable discrimination among the studied fluorinated and non-fluorinated 2- and/or 4-thio analogues of dUMP. The binding free energies of monothio analogues of dUMP and 5-fluoro-dUMP correspond quite well with experimentally measured activities of these nucleotides in the thymidylate synthase reaction. On the other hand, the binding free energies of both dithio analogues, 2,4-dithio-dUMP and 2,4-dithio-FdUMP, show lack of such correlation. The latter suggests that very low activities of the dithio analogues of dUMP and 5-fluoro-dUMP may relate more to the covalent reaction of these nucleotides within the ternary complex with TS and 5,10-methylenetetrahydrofolate, than to their pre-covalent binding. We speculate that a lack of substrate activity of 2,4-dithio-dUMP is related to the high aromaticity of its pyrimidine ring that prevents the Michael addition of the active site cysteine thiol to the pyrimidine C6 atom. A stronger affinity of the fluorinated analogues of dUMP to thymidylate synthase, compared to the non-fluorinated congeners, results from the fluorine substituent producing a local strain in the C6 region in the pyrimidine ring, thus sensitizing C6 to the Michael addition of the cysteine thiol.
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Affiliation(s)
- Adam Jarmuła
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., 02-093 Warszawa, Poland.
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Abstract
The genomics revolution has provided a deluge of new targets for drug discovery. To facilitate the drug discovery process, many researchers are turning to fragment-based approaches to find lead molecules more efficiently. One such method, Tethering1, allows for the identification of small-molecule fragments that bind to specific regions of a protein target. These fragments can then be elaborated, combined with other molecules, or combined with one another to provide high-affinity drug leads. In this review we describe the background and theory behind Tethering and discuss its use in identifying novel inhibitors for protein targets including interleukin-2 (IL-2), thymidylate synthase (TS), protein tyrosine phosphatase 1B (PTP-1B), and caspases.
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Affiliation(s)
- Daniel A Erlanson
- Sunesis Pharmaceuticals, Inc., 341 Oyster Point Boulevard, South San Francisco, California 94080, USA.
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Affiliation(s)
- Daniel A Erlanson
- Sunesis Pharmaceuticals Inc., 341 Oyster Point Boulevard, South San Francisco, CA 94080, USA.
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48
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Aronov AM, Bemis GW. A minimalist approach to fragment-based ligand design using common rings and linkers: Application to kinase inhibitors. Proteins 2004; 57:36-50. [PMID: 15326593 DOI: 10.1002/prot.20173] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present a novel method for stepwise scaffold assembly that integrates fragment-by-fragment ligand design approaches with high-throughput virtual library screening (COREGEN). As an extension of our earlier studies of common features present in drug molecules, we investigate the hypothesis that most pharmaceutically interesting ligands can be expressed in terms of the ring-linker frameworks that comprise them. Analysis of 119 published kinase inhibitors from at least 18 different targets illustrates that a basis set of 4 rings and 8 linkers is sufficient to describe approximately 90% of ring and linker occurrences, respectively. A similar result was derived from a larger set of approximately 40,000 kinase inhibitors from curated patents. A method for ring-linker-based assembly of scaffold libraries that uses experimental information to guide the placement of anchor fragments is validated using a set of reported kinase inhibitors of Bcr-Abl, Cdk2, and Src. In every case, the predominant structural motif of reported ligand cores is reproduced and variations are suggested. To underscore generality of this approach, a novel scaffold for a cyclooxygenase-2 (COX-2) selective ligand is proposed.
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Affiliation(s)
- Alex M Aronov
- Vertex Pharmaceuticals Inc., Cambridge, Massachusetts 02139-4242, USA.
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Gutteridge A, Thornton J. Conformational change in substrate binding, catalysis and product release: an open and shut case? FEBS Lett 2004; 567:67-73. [PMID: 15165895 DOI: 10.1016/j.febslet.2004.03.067] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Revised: 03/01/2004] [Accepted: 03/07/2004] [Indexed: 11/18/2022]
Abstract
The role of conformational change in substrate binding, catalysis and product release is reviewed for 11 enzymes, for which crystal structures are available for the apo, substrate- and product-bound states. The extent of global conformational changes is measured, and the movements of the functional regions involved in catalysis and ligand binding are compared to the rest of the structure. We find that most of these enzymes undergo relatively small amounts of conformational change and particularly small changes in catalytic residue geometry, usually less than 1 A. In some enzymes there is significant movement of the binding residues, usually on surface loops.
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Affiliation(s)
- Alex Gutteridge
- EBI, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SD, UK.
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50
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Abstract
The successful practice of medicinal chemistry is crucially dependent on the principles of molecular recognition: the first and "fundamental" requirement for a drug is to bind to its target; specificity, or at least selectivity, of binding is also a must. Subsequent optimization steps to develop a lead compound into a drug are a complex mixture of processes that are not yet fully understood or predictable. Fortunately, criteria exist to discard leads that would be intractable for optimization. The concepts of non-lead-likeness and lead-likeness, in respect to drug-likeness and non-drug-likeness, have prompted a rich discussion in the recent medicinal chemistry literature. The fragment approach is an emerging philosophy in the process of lead compound discovery. The basic interactions responsible for binding affinity are defined from the "protein interactions world" and key structural fragments are combined according to the criteria of three-dimensional diversity to find new leads. New techniques in screening are used for the detection of the weaker interactions of fragments with their targets that might be undetectable in classical biological assays.
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Affiliation(s)
- Daniela Fattori
- Menarini Ricerche S.p.A., Chemistry Departmen,t Via Tito Speri 10, I-00040 Pomezia, Rome, Italy
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