1
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Wu D, Salsbury FR. Allosteric Modulation of Thrombin by Thrombomodulin: Insights from Logistic Regression and Statistical Analysis of Molecular Dynamics Simulations. ACS OMEGA 2024; 9:23086-23100. [PMID: 38826540 PMCID: PMC11137727 DOI: 10.1021/acsomega.4c03375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/01/2024] [Accepted: 05/08/2024] [Indexed: 06/04/2024]
Abstract
Thrombomodulin (TM), a transmembrane receptor integral to the anticoagulant pathway, governs thrombin's substrate specificity via interaction with thrombin's anion-binding exosite I. Despite its established role, the precise mechanisms underlying this regulatory function are yet to be fully unraveled. In this study, we deepen the understanding of these mechanisms through eight independent 1 μs all-atom simulations, analyzing thrombin both in its free form and when bound to TM fragments TM456 and TM56. Our investigations revealed distinct and significant conformational changes in thrombin mediated by the binding of TM56 and TM456. While TM56 predominantly influences motions within exosite I, TM456 orchestrates coordinated alterations across various loop regions, thereby unveiling a multifaceted modulatory role that extends beyond that of TM56. A highlight of our study is the identification of critical hydrogen bonds that undergo transformations during TM56 and TM456 binding, shedding light on the pivotal allosteric influence exerted by TM4 on thrombin's structural dynamics. This work offers a nuanced appreciation of TM's regulatory role in blood coagulation, paving the way for innovative approaches in the development of anticoagulant therapies and expanding the horizons in oncology therapeutics through a deeper understanding of molecular interactions in the coagulation pathway.
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Affiliation(s)
- Dizhou Wu
- Department of Physics, Wake
Forest University, Winston-Salem, North Carolina 27106, United
States
| | - Freddie R. Salsbury
- Department of Physics, Wake
Forest University, Winston-Salem, North Carolina 27106, United
States
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2
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Wu D, Prem A, Xiao J, Salsbury FR. Thrombin - A Molecular Dynamics Perspective. Mini Rev Med Chem 2024; 24:1112-1124. [PMID: 37605420 DOI: 10.2174/1389557523666230821102655] [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: 03/13/2023] [Revised: 07/08/2023] [Accepted: 07/15/2023] [Indexed: 08/23/2023]
Abstract
Thrombin is a crucial enzyme involved in blood coagulation, essential for maintaining circulatory system integrity and preventing excessive bleeding. However, thrombin is also implicated in pathological conditions such as thrombosis and cancer. Despite the application of various experimental techniques, including X-ray crystallography, NMR spectroscopy, and HDXMS, none of these methods can precisely detect thrombin's dynamics and conformational ensembles at high spatial and temporal resolution. Fortunately, molecular dynamics (MD) simulation, a computational technique that allows the investigation of molecular functions and dynamics in atomic detail, can be used to explore thrombin behavior. This review summarizes recent MD simulation studies on thrombin and its interactions with other biomolecules. Specifically, the 17 studies discussed here provide insights into thrombin's switch between 'slow' and 'fast' forms, active and inactive forms, the role of Na+ binding, the effects of light chain mutation, and thrombin's interactions with other biomolecules. The findings of these studies have significant implications for developing new therapies for thrombosis and cancer. By understanding thrombin's complex behavior, researchers can design more effective drugs and treatments that target thrombin.
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Affiliation(s)
- Dizhou Wu
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27106, USA
| | - Athul Prem
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27106, USA
| | - Jiajie Xiao
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27106, USA
- Freenome, South San Francisco, CA, 94080, USA
| | - Freddie R Salsbury
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27106, USA
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3
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Heurich M, McCluskey G. Complement and coagulation crosstalk - Factor H in the spotlight. Immunobiology 2023; 228:152707. [PMID: 37633063 DOI: 10.1016/j.imbio.2023.152707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/02/2023] [Accepted: 07/10/2023] [Indexed: 08/28/2023]
Abstract
The immune complement and the coagulation systems are blood-based proteolytic cascades that are activated by pathway-specific triggers, based on protein-protein interactions and enzymatic cleavage reactions. Activation of these systems is finely balanced and controlled through specific regulatory mechanisms. The complement and coagulation systems are generally viewed as distinct, but have common evolutionary origins, and several interactions between these homologous systems have been reported. This complement and coagulation crosstalk can affect activation, amplification and regulatory functions in both systems. In this review, we summarize the literature on coagulation factors contributing to complement alternative pathway activation and regulation and highlight molecular interactions of the complement alternative pathway regulator factor H with several coagulation factors. We propose a mechanism where factor H interactions with coagulation factors may contribute to both complement and coagulation activation and regulation within the haemostatic system and fibrin clot microenvironment and introduce the emerging role of factor H as a modulator of coagulation. Finally, we discuss the potential impact of these protein interactions in diseases associated with factor H dysregulation or deficiency as well as evidence of coagulation dysfunction.
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Affiliation(s)
- Meike Heurich
- School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, United Kingdom.
| | - Geneviève McCluskey
- Université Paris-Saclay, INSERM, Hémostase, Inflammation, Thrombose HITH U1176, 94276 Le Kremlin-Bicêtre, France
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4
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Wu D, Salsbury FR. Unraveling the Role of Hydrogen Bonds in Thrombin via Two Machine Learning Methods. J Chem Inf Model 2023; 63:3705-3718. [PMID: 37285464 PMCID: PMC11164249 DOI: 10.1021/acs.jcim.3c00153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Hydrogen bonds play a critical role in the folding and stability of proteins, such as proteins and nucleic acids, by providing strong and directional interactions. They help to maintain the secondary and 3D structure of proteins, and structural changes in these molecules often result from the formation or breaking of hydrogen bonds. To gain insights into these hydrogen bonding networks, we applied two machine learning models - a logistic regression model and a decision tree model - to study four variants of thrombin: wild-type, ΔK9, E8K, and R4A. Our results showed that both models have their unique advantages. The logistic regression model highlighted potential key residues (GLU295) in thrombin's allosteric pathways, while the decision tree model identified important hydrogen bonding motifs. This information can aid in understanding the mechanisms of folding in proteins and has potential applications in drug design and other therapies. The use of these two models highlights their usefulness in studying hydrogen bonding networks in proteins.
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Affiliation(s)
- Dizhou Wu
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106, United States
| | - Freddie R Salsbury
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106, United States
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5
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Simulations suggest double sodium binding induces unexpected conformational changes in thrombin. J Mol Model 2022; 28:120. [PMID: 35419655 PMCID: PMC9186379 DOI: 10.1007/s00894-022-05076-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/26/2022] [Indexed: 10/18/2022]
Abstract
Thrombin is a Na[Formula: see text]-activated serine protease existing in two forms targeted to procoagulant and anticoagulant activities, respectively. There is one Na[Formula: see text]-binding site that has been the focus of the study of the thrombin. However, molecular dynamics (MD) simulations suggest that there might be actually two Na[Formula: see text]-binding sites in thrombin and that Na[Formula: see text] ions can even bind to two sites simultaneously. In this study, we performed 12 independent 2-µs all-atom MD simulations for the wild-type (WT) thrombin and we studied the effects of the different Na[Formula: see text] binding modes on thrombin. From the root-mean-square fluctuations (RMSF) for the [Formula: see text]-carbons, we see that the atomic fluctuations mainly change in the 60s, 170s, and 220s loops, and the connection (residue 167 to 170). The correlation matrices for different binding modes suggest regions that may play an important role in thrombin's allosteric response and provide us a possible allosteric pathway for the sodium binding. Amorim-Hennig (AH) clustering tells us how the structure of the regions of interest changes on sodium binding. Principal component analysis (PCA) shows us how the different regions of thrombin change conformation together with sodium binding. Solvent-accessible surface area (SASA) exposes the conformational change in exosite I and catalytic triad. Finally, we argue that the double binding mode might be an inactive mode and that the kinetic scheme for the Na[Formula: see text] binding to thrombin might be a multiple-step mechanism rather than a 2-step mechanism.
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Exosite Binding in Thrombin: A Global Structural/Dynamic Overview of Complexes with Aptamers and Other Ligands. Int J Mol Sci 2021; 22:ijms221910803. [PMID: 34639143 PMCID: PMC8509272 DOI: 10.3390/ijms221910803] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/24/2021] [Accepted: 10/01/2021] [Indexed: 12/13/2022] Open
Abstract
Thrombin is the key enzyme of the entire hemostatic process since it is able to exert both procoagulant and anticoagulant functions; therefore, it represents an attractive target for the developments of biomolecules with therapeutic potential. Thrombin can perform its many functional activities because of its ability to recognize a wide variety of substrates, inhibitors, and cofactors. These molecules frequently are bound to positively charged regions on the surface of protein called exosites. In this review, we carried out extensive analyses of the structural determinants of thrombin partnerships by surveying literature data as well as the structural content of the Protein Data Bank (PDB). In particular, we used the information collected on functional, natural, and synthetic molecular ligands to define the anatomy of the exosites and to quantify the interface area between thrombin and exosite ligands. In this framework, we reviewed in detail the specificity of thrombin binding to aptamers, a class of compounds with intriguing pharmaceutical properties. Although these compounds anchor to protein using conservative patterns on its surface, the present analysis highlights some interesting peculiarities. Moreover, the impact of thrombin binding aptamers in the elucidation of the cross-talk between the two distant exosites is illustrated. Collectively, the data and the work here reviewed may provide insights into the design of novel thrombin inhibitors.
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7
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Abstract
Thrombin plays an important role in the process of hemostasis and blood coagulation. Studies in thrombin can help us find ways to treat cancer because thrombin is able to reduce the characteristic hypercoagulability of cancer. Thrombin is composed of two chains, the light chain and the heavy chain. The function of the heavy chain has been largely explored, while the function of the light chain was obscured until several disease-associated mutations in the light chain come to light. In this study, we want to explore the dynamic and conformation effects of mutations on the light chain further to determine possible associations between mutation, conformational changes, and disease. The study, which is a follow-up for our studies on apo thrombin and the mutant, ΔK9, mainly focuses on the mutants E8K and R4A. E8K is a disease-associated mutation, and R4A is used to study the role of Arg4, which is suggested experimentally to play a critical role for thrombin's catalytic activities. We performed five all-atom one microsecond-scale molecular dynamics (MD) simulations for both E8K and R4A, and quantified the changes in the conformational ensemble of the mutants. From the root-mean-square fluctuations (RMSF) for the α-carbons, we find that the atomic fluctuations change in the mutants in the 60s loop and γ loop. The correlation coefficients for the α-carbons indicate that the correlation relation for atom-pairs in the protein is also impacted. The clustering analysis and the principal component analysis (PCA) consistently tell us that the catalytic pocket and the regulatory loops are destabilized by the mutations. We also find that there are two binding modes for Na+ by clustering the vector difference between the Na+ ions and the 220s loop. After further analysis, we find that there is a relation between the Na+ binding and the rigidification of the γ loop, which may shed light on the mysterious role of the γ loop in thrombin.
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Affiliation(s)
- Dizhou Wu
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106 United States
| | - Jiajie Xiao
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106 United States
- Freenome, South San Francisco, California 94080 United States
| | - Freddie R Salsbury
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27106 United States
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8
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Barkhordari A, Behzad-Behbahani A, Jajarmi V, Bandehpour M, Rafiei-Dehbidi G, Safari F, Mahboudi F, Kazemi B. Direct Cloning, Expression and Purification of Human Activated Thrombin in Prokaryotic System and CD Analysis Report of Produced Thrombin: Molecular Characterization of Recombinant Thrombin. Int J Pept Res Ther 2020. [DOI: 10.1007/s10989-020-10046-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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9
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Tang Z, Ren Y, Liu F. Identify thrombin inhibitor with novel skeleton based on virtual screening study. J Biomol Struct Dyn 2020; 40:499-507. [PMID: 32876545 DOI: 10.1080/07391102.2020.1815580] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Virtual screening refers to the screening of active compounds based on a small-molecule database. This procedure can rapidly select active compounds with pharmaceutical properties from millions of molecules, thus considerably reducing the number of experimental screening compounds and cost of drug development and shortening the research cycle. In this paper, a pharmacophore screening method was used for virtual screening to determine new scaffold compounds with potential anticoagulant activities. The pharmacophore model (Model_01-20) was constructed in SYBYL-X 2.0 based on dabigatran derivatives (D1-D9) with micromolar to nanomolar activities and tested by decoy test method. Model_01 was selected to screen more than 1600 million compounds in the Zinc 12.0 database. Furtherly, molecular docking analysis and ADME prediction were conducted on more than 100,000 screened compounds. Finally, two compounds (Z-19 and Z-29) were selected for anticoagulant activity test in vitro, Compound Z-29 with tryptophan aurone structure was found possess anticoagulant effect and its IC50 = 22.9 ± 6.88 μM. ADME prediction results show that compound Z-29 features a high intestinal absorption rate, which is valuable for further in-depth research. The research results of this paper can be used for further structural modification and optimisation to guide the design and provide new ideas and methods for the discovery of new thrombin inhibitors.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Zhipeng Tang
- College of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
| | - Yujie Ren
- College of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
| | - Fei Liu
- College of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
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10
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Troisi R, Balasco N, Vitagliano L, Sica F. Molecular dynamics simulations of human α-thrombin in different structural contexts: evidence for an aptamer-guided cooperation between the two exosites. J Biomol Struct Dyn 2020; 39:2199-2209. [PMID: 32202471 DOI: 10.1080/07391102.2020.1746693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Human α-thrombin (thrombin) is a multifunctional enzyme that plays a pivotal role in the coagulation pathway. Thrombin activity can be effectively modulated by G-quadruplex-based oligonucleotide aptamers that specifically interact with the two positively charged regions (exosites I and II) on the protein surface. Although insightful atomic-level snapshots of the recognition between thrombin and aptamers have been recently achieved through crystallographic analyses, some dynamic aspects of this interaction have not been fully characterized. We here report molecular dynamics simulations of thrombin in different association states: ligand-free and binary/ternary complexes with the aptamers TBA (at exosite I) and HD22_27mer (at exosite II). The simulations carried out on the binary and ternary complexes formed by thrombin with these aptamers provide a dynamic view of the interactions that stabilize them in a crystal-free environment. Interestingly, the analysis of the dynamics of the exosites in different thrombin binding states clearly indicates that the HD22_27mer binding at the exosite II favours conformations of exosite I that are prone to the TBA binding. Similar effects are observed upon the binding of TBA to the exosite I. These observations provide an atomic-level picture of the exosite inter-communication in thrombin and explain the experimentally detected cooperativity of the TBA/HD22_27mer binding.
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Affiliation(s)
- Romualdo Troisi
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Nicole Balasco
- Institute of Biostructures and Bioimaging, CNR, Naples, Italy
| | | | - Filomena Sica
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
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11
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Catani MV, Savini I, Tullio V, Gasperi V. The "Janus Face" of Platelets in Cancer. Int J Mol Sci 2020; 21:ijms21030788. [PMID: 31991775 PMCID: PMC7037171 DOI: 10.3390/ijms21030788] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/21/2020] [Accepted: 01/22/2020] [Indexed: 12/20/2022] Open
Abstract
Besides their vital role in hemostasis and thrombosis, platelets are also recognized to be involved in cancer, where they play an unexpected central role: They actively influence cancer cell behavior, but, on the other hand, platelet physiology and phenotype are impacted by tumor cells. The existence of this platelet-cancer loop is supported by a large number of experimental and human studies reporting an association between alterations in platelet number and functions and cancer, often in a way dependent on patient, cancer type and treatment. Herein, we shall report on an update on platelet-cancer relationships, with a particular emphasis on how platelets might exert either a protective or a deleterious action in all steps of cancer progression. To this end, we will describe the impact of (i) platelet count, (ii) bioactive molecules secreted upon platelet activation, and (iii) microvesicle-derived miRNAs on cancer behavior. Potential explanations of conflicting results are also reported: Both intrinsic (heterogeneity in platelet-derived bioactive molecules with either inhibitory or stimulatory properties; features of cancer cell types, such as aggressiveness and/or tumour stage) and extrinsic (heterogeneous characteristics of cancer patients, study design and sample preparation) factors, together with other confounding elements, contribute to “the Janus face” of platelets in cancer. Given the difficulty to establish the univocal role of platelets in a tumor, a better understanding of their exact contribution is warranted, in order to identify an efficient therapeutic strategy for cancer management, as well as for better prevention, screening and risk assessment protocols.
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Affiliation(s)
- Maria Valeria Catani
- Correspondence: (M.V.C.); (V.G.); Tel.: +39-06-72596465 (M.V.C.); +39-06-72596465 (V.G.)
| | | | | | - Valeria Gasperi
- Correspondence: (M.V.C.); (V.G.); Tel.: +39-06-72596465 (M.V.C.); +39-06-72596465 (V.G.)
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12
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Sodium-induced population shift drives activation of thrombin. Sci Rep 2020; 10:1086. [PMID: 31974511 PMCID: PMC6978324 DOI: 10.1038/s41598-020-57822-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 01/06/2020] [Indexed: 02/04/2023] Open
Abstract
The equilibrium between active E and inactive E* forms of thrombin is assumed to be governed by the allosteric binding of a Na+ ion. Here we use molecular dynamics simulations and Markov state models to sample transitions between active and inactive states. With these calculations we are able to compare thermodynamic and kinetic properties depending on the presence of Na+. For the first time, we directly observe sodium-induced conformational changes in long-timescale computer simulations. Thereby, we are able to explain the resulting change in activity. We observe a stabilization of the active form in presence of Na+ and a shift towards the inactive form in Na+-free simulations. We identify key structural features to quantify and monitor this conformational shift. These include the accessibility of the S1 pocket and the reorientation of W215, of R221a and of the Na+ loop. The structural characteristics exhibit dynamics at various timescales: Conformational changes in the Na+ binding loop constitute the slowest observed movement. Depending on its orientation, it induces conformational shifts in the nearby substrate binding site. Only after this shift, residue W215 is able to move freely, allowing thrombin to adopt a binding-competent conformation.
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13
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Chen J, Wang X, Pang L, Zhang JZH, Zhu T. Effect of mutations on binding of ligands to guanine riboswitch probed by free energy perturbation and molecular dynamics simulations. Nucleic Acids Res 2020; 47:6618-6631. [PMID: 31173143 PMCID: PMC6649850 DOI: 10.1093/nar/gkz499] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/22/2019] [Accepted: 05/29/2019] [Indexed: 12/14/2022] Open
Abstract
Riboswitches can regulate gene expression by direct and specific interactions with ligands and have recently attracted interest as potential drug targets for antibacterial. In this work, molecular dynamics (MD) simulations, free energy perturbation (FEP) and molecular mechanics generalized Born surface area (MM-GBSA) methods were integrated to probe the effect of mutations on the binding of ligands to guanine riboswitch (GR). The results not only show that binding free energies predicted by FEP and MM-GBSA obtain an excellent correlation, but also indicate that mutations involved in the current study can strengthen the binding affinity of ligands GR. Residue-based free energy decomposition was applied to compute ligand-nucleotide interactions and the results suggest that mutations highly affect interactions of ligands with key nucleotides U22, U51 and C74. Dynamics analyses based on MD trajectories indicate that mutations not only regulate the structural flexibility but also change the internal motion modes of GR, especially for the structures J12, J23 and J31, which implies that the aptamer domain activity of GR is extremely plastic and thus readily tunable by nucleotide mutations. This study is expected to provide useful molecular basis and dynamics information for the understanding of the function of GR and possibility as potential drug targets for antibacterial.
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Affiliation(s)
- Jianzhong Chen
- School of Science, Shandong Jiaotong University, Jinan 250357 China
| | - Xingyu Wang
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
| | - Laixue Pang
- School of Science, Shandong Jiaotong University, Jinan 250357 China
| | - John Z H Zhang
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China.,Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
| | - Tong Zhu
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China.,Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
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14
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Abstract
Classically, phenotype is what is observed, and genotype is the genetic makeup. Statistical studies aim to project phenotypic likelihoods of genotypic patterns. The traditional genotype-to-phenotype theory embraces the view that the encoded protein shape together with gene expression level largely determines the resulting phenotypic trait. Here, we point out that the molecular biology revolution at the turn of the century explained that the gene encodes not one but ensembles of conformations, which in turn spell all possible gene-associated phenotypes. The significance of a dynamic ensemble view is in understanding the linkage between genetic change and the gained observable physical or biochemical characteristics. Thus, despite the transformative shift in our understanding of the basis of protein structure and function, the literature still commonly relates to the classical genotype-phenotype paradigm. This is important because an ensemble view clarifies how even seemingly small genetic alterations can lead to pleiotropic traits in adaptive evolution and in disease, why cellular pathways can be modified in monogenic and polygenic traits, and how the environment may tweak protein function.
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Affiliation(s)
- Ruth Nussinov
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chung-Jung Tsai
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Hyunbum Jang
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
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15
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Xiao J, Melvin RL, Salsbury FR. Probing light chain mutation effects on thrombin via molecular dynamics simulations and machine learning. J Biomol Struct Dyn 2019; 37:982-999. [PMID: 29471734 PMCID: PMC6207482 DOI: 10.1080/07391102.2018.1445032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 02/17/2018] [Indexed: 12/13/2022]
Abstract
Thrombin is a key component for chemotherapeutic and antithrombotic therapy development. As the physiologic and pathologic roles of the light chain still remain vague, here, we continue previous efforts to understand the impacts of the disease-associated single deletion of LYS9 in the light chain. By combining supervised and unsupervised machine learning methodologies and more traditional structural analyses on data from 10 μs molecular dynamics simulations, we show that the conformational ensemble of the ΔK9 mutant is significantly perturbed. Our analyses consistently indicate that LYS9 deletion destabilizes both the catalytic cleft and regulatory functional regions and result in some conformational changes that occur in tens to hundreds of nanosecond scaled motions. We also reveal that the two forms of thrombin each prefer a distinct binding mode of a Na+ ion. We expand our understanding of previous experimental observations and shed light on the mechanisms of the LYS9 deletion associated bleeding disorder by providing consistent but more quantitative and detailed structural analyses than early studies in literature. With a novel application of supervised learning, i.e. the decision tree learning on the hydrogen bonding features in the wild-type and ΔK9 mutant forms of thrombin, we predict that seven pairs of critical hydrogen bonding interactions are significant for establishing distinct behaviors of wild-type thrombin and its ΔK9 mutant form. Our calculations indicate the LYS9 in the light chain has both localized and long-range allosteric effects on thrombin, supporting the opinion that light chain has an important role as an allosteric effector.
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Affiliation(s)
- Jiajie Xiao
- Department of Physics, Wake Forest University, Winston-Salem, USA
- Department of Computer Science, Wake Forest University, Winston Salem, USA
| | - Ryan L. Melvin
- Department of Physics, Wake Forest University, Winston-Salem, USA
- Department of Mathematics and Statistics, Wake Forest University, Winston-Salem,USA
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16
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Xiao J, Salsbury FR. Na +-binding modes involved in thrombin's allosteric response as revealed by molecular dynamics simulations, correlation networks and Markov modeling. Phys Chem Chem Phys 2019; 21:4320-4330. [PMID: 30724273 PMCID: PMC6993936 DOI: 10.1039/c8cp07293k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The monovalent sodium ion (Na+) is a critical modulator of thrombin. However, the mechanism of thrombin's activation by Na+ has been widely debated for more than twenty years. Details of the linkage between thrombin and Na+ remain vague due to limited temporal and spatial resolution in experiments. In this work, we combine microsecond scale atomic-detailed molecular dynamics simulations with correlation network analyses and hidden Markov modeling to probe the detailed thermodynamic and kinetic picture of Na+-binding events and their resulting allosteric responses in thrombin. We reveal that ASP189 and ALA190 comprise a stable Na+-binding site (referred as "inner" Na+-binding site) along with the previously known one (referred as "outer" Na+-binding site). The corresponding newly identified Na+-binding mode introduces significant allosteric responses in thrombin's regulatory regions by stabilizing selected torsion angles of residues responsive to Na+-binding. Our Markov model indicates that the bound Na+ prefers to transfer between the two Na+-binding sites when an unbinding event takes place. These results suggest a testable hypothesis of a substrate-driven Na+ migration (ΔG ∼ 1.7 kcal mol-1) from the "inner" Na+-binding site to the "outer" one during thrombin's catalytic activities. The binding of a Na+ ion at the "inner" Na+-binding site should be inferred as a prerequisite for thrombin's efficient recognition to the substrate, which opens a new angle for our understanding of Na+-binding's allosteric activation on thrombin and sheds light on detailed processes in thrombin's activation.
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Affiliation(s)
- Jiajie Xiao
- Department of Physics, Wake Forest University, Winston Salem, NC, USA.
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Dissecting a novel allosteric mechanism of cruzain: A computer-aided approach. PLoS One 2019; 14:e0211227. [PMID: 30682119 PMCID: PMC6347273 DOI: 10.1371/journal.pone.0211227] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 01/09/2019] [Indexed: 02/08/2023] Open
Abstract
Trypanosoma cruzi is the causative agent of Chagas disease, a neglected infection affecting millions of people in tropical regions. There are several chemotherapeutic agents for the treatment of this disease, but most of them are highly toxic and generate resistance. Currently, the development of allosteric inhibitors constitutes a promising research field, since it can improve the accessibility to more selective and less toxic medicines. To date, the allosteric drugs prediction is a state-of-the-art topic in rational structure-based computational design. In this work, a simulation strategy was developed for computational discovery of allosteric inhibitors, and it was applied to cruzain, a promising target and the major cysteine protease of T. cruzi. Molecular dynamics simulations, binding free energy calculations and network-based modelling of residue interactions were combined to characterize and compare molecular distinctive features of the apo form and the cruzain-allosteric inhibitor complexes. By using geometry-based criteria on trajectory snapshots, we predicted two main allosteric sites suitable for drug targeting. The results suggest dissimilar mechanisms exerted by the same allosteric site when binding different potential allosteric inhibitors. Finally, we identified the residues involved in suboptimal paths linking the identified site and the orthosteric site. The present study constitutes the first approximation to the design of cruzain allosteric inhibitors and may serve for future pharmacological intervention. Here, no major effects on active site structure were observed due to compound binding (modification of distance and angles between catalytic residues), which indicates that allosteric regulation in cruzain might be mediated via alterations of its dynamical properties similarly to allosteric inhibition of human cathepsin K (HCatK). The current findings are particularly relevant for the design of allosteric modulators of papain-like cysteine proteases.
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Melvin RL, Xiao J, Berenhaut KS, Godwin RC, Salsbury FR. Using correlated motions to determine sufficient sampling times for molecular dynamics. Phys Rev E 2018; 98:023307. [PMID: 30253618 PMCID: PMC6325644 DOI: 10.1103/physreve.98.023307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Indexed: 06/08/2023]
Abstract
Here we present a time-dependent correlation method that provides insight into how long a system takes to grow into its equal-time (Pearson) correlation. We also show a usage of an extant time-lagged correlation method that indicates the time for parts of a system to become decorrelated, relative to equal-time correlation. Given a completed simulation (or set of simulations), these tools estimate (i) how long of a simulation of the same system would be sufficient to observe the same correlated motions, (ii) if patterns of observed correlated motions indicate events beyond the timescale of the simulation, and (iii) how long of a simulation is needed to observe these longer timescale events. We view this method as a decision-support tool that will aid researchers in determining necessary sampling times. In principle, this tool is extendable to any multidimensional time series data with a notion of correlated fluctuations; however, here we limit our discussion to data from molecular-dynamics simulations.
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Affiliation(s)
- Ryan L. Melvin
- Department of Physics and Department of Mathematics and Statistics, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA
| | - Jiajie Xiao
- Department of Physics and Department of Computer Science, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA
| | - Kenneth S. Berenhaut
- Department of Mathematics and Statistics, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA
| | - Ryan C. Godwin
- Department of Physics, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA
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Yu M, Ma X, Cao H, Chong B, Lai L, Liu Z. Singular value decomposition for the correlation of atomic fluctuations with arbitrary angle. Proteins 2018; 86:1075-1087. [PMID: 30019778 DOI: 10.1002/prot.25586] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 06/22/2018] [Accepted: 07/04/2018] [Indexed: 01/21/2023]
Abstract
Many proteins exhibit a critical property called allostery, which enables intra-molecular transmission of information between distal sites. Microscopically, allosteric response is closely related to correlated atomic fluctuations. Conventional correlation analysis correlates the atomic fluctuations at two sites by taking the dot product (DP) between the fluctuations, which accounts only for the parallel and antiparallel components. Here, we present a singular value decomposition (SVD) method that analyzes the correlation coefficient of fluctuation dynamics with an arbitrary angle between the correlated directions. In a model allosteric system, the second PDZ domain (PDZ2) in the human PTP1E protein, approximately one third of the strong correlations have near-perpendicular directions, which are underestimated in the conventional method. The discrimination becomes more prominent for residue pairs with larger separation. The results of the proposed SVD method are more consistent with the experimentally determined PDZ2 dynamics than those of conventional method. In addition, the SVD method improved the prediction accuracy of the allosteric sites in a dataset of 23 known allosteric monomer proteins. The proposed method may inspire extended investigation not only into allostery, but also into protein dynamics and drug design.
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Affiliation(s)
- Miao Yu
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Xiaomin Ma
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong Province, China
| | - Huaiqing Cao
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Bin Chong
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Luhua Lai
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China.,Center for Quantitative Biology, and BNLMS, Peking University, Beijing, China.,State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Peking University, Beijing, China
| | - Zhirong Liu
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China.,Center for Quantitative Biology, and BNLMS, Peking University, Beijing, China.,State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Peking University, Beijing, China
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Peacock RB, Davis JR, Markwick PRL, Komives EA. Dynamic Consequences of Mutation of Tryptophan 215 in Thrombin. Biochemistry 2018; 57:2694-2703. [PMID: 29634247 DOI: 10.1021/acs.biochem.8b00262] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thrombin normally cleaves fibrinogen to promote coagulation; however, binding of thrombomodulin to thrombin switches the specificity of thrombin toward protein C, triggering the anticoagulation pathway. The W215A thrombin mutant was reported to have decreased activity toward fibrinogen without significant loss of activity toward protein C. To understand how mutation of Trp215 may alter thrombin specificity, hydrogen-deuterium exchange experiments (HDXMS), accelerated molecular dynamics (AMD) simulations, and activity assays were carried out to compare the dynamics of Trp215 mutants with those of wild type (WT) thrombin. Variation in NaCl concentration had no detectable effect on the sodium-binding (220sCT) loop, but appeared to affect other surface loops. Trp215 mutants showed significant increases in amide exchange in the 170sCT loop consistent with a loss of H-bonding in this loop identified by the AMD simulations. The W215A thrombin showed increased amide exchange in the 220sCT loop and in the N-terminus of the heavy chain. The AMD simulations showed that a transient conformation of the W215A thrombin has a distorted catalytic triad. HDXMS experiments revealed that mutation of Phe227, which engages in a π-stacking interaction with Trp215, also caused significantly increased amide exchange in the 170sCT loop. Activity assays showed that only the F227V mutant had wild type catalytic activity, whereas all other mutants showed markedly lower activity. Taken together, the results explain the reduced pro-coagulant activity of the W215A mutant and demonstrate the allosteric connection between Trp215, the sodium-binding loop, and the active site.
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Abdel Aziz MH, Desai UR. Novel heparin mimetics reveal cooperativity between exosite 2 and sodium-binding site of thrombin. Thromb Res 2018; 165:61-67. [PMID: 29573721 DOI: 10.1016/j.thromres.2018.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 02/28/2018] [Accepted: 03/16/2018] [Indexed: 01/23/2023]
Abstract
INTRODUCTION Thrombin is a primary target of most anticoagulants. Yet, thrombin's dual and opposing role in pro- as well as anti- coagulant processes imposes considerable challenges in discovering finely tuned regulators that maintain homeostasis, rather than disproportionately changing the equilibrium to one side. In this connection, we have been studying exosite 2-mediated allosteric modulation of thrombin activity using synthetic agents called low molecular weight lignins (LMWLs). Although the aromatic scaffold of LMWLs is completely different from the polysaccharidic scaffold of heparin, the presence of multiple negatively charged groups on both ligands induces binding to exosite 2 of thrombin. This work characterizes the nature of interactions between LMWLs and thrombin to understand the energetic cooperativity between exosite 2 and active site of thrombin. MATERIALS AND METHODS The thermodynamics of thrombin-LMWL complexes was studied using spectrofluorimetric titrations as a function of ionic strength and temperature of the buffer. The contributions of enthalpy and entropy to binding were evaluated using classic thermodynamic equations. Label-free surface plasmon resonance was used to assess the role of sodium ion in LMWL binding to thrombin at a fixed ionic strength. RESULTS AND CONCLUSIONS Exosite 2-induced conformational change in thrombin's active site is strongly dependent on the structure of the ligand, which has consequences with respect to regulation of thrombin. The ionic and non-ionic contributions to binding affinity and the thermodynamic signature were highly ligand specific. Interestingly, LMWLs display preference for the sodium-bound form of thrombin, which supports the existence of an energetic coupling between exosite 2 and sodium-binding site of thrombin.
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Affiliation(s)
- May H Abdel Aziz
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23219, United States
| | - Umesh R Desai
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23219, United States; Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, VA 23219, United States.
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De Luca C, Virtuoso A, Maggio N, Papa M. Neuro-Coagulopathy: Blood Coagulation Factors in Central Nervous System Diseases. Int J Mol Sci 2017; 18:E2128. [PMID: 29023416 PMCID: PMC5666810 DOI: 10.3390/ijms18102128] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 09/30/2017] [Accepted: 10/08/2017] [Indexed: 12/30/2022] Open
Abstract
Blood coagulation factors and other proteins, with modulatory effects or modulated by the coagulation cascade have been reported to affect the pathophysiology of the central nervous system (CNS). The protease-activated receptors (PARs) pathway can be considered the central hub of this regulatory network, mainly through thrombin or activated protein C (aPC). These proteins, in fact, showed peculiar properties, being able to interfere with synaptic homeostasis other than coagulation itself. These specific functions modulate neuronal networks, acting both on resident (neurons, astrocytes, and microglia) as well as circulating immune system cells and the extracellular matrix. The pleiotropy of these effects is produced through different receptors, expressed in various cell types, in a dose- and time-dependent pattern. We reviewed how these pathways may be involved in neurodegenerative diseases (amyotrophic lateral sclerosis, Alzheimer's and Parkinson's diseases), multiple sclerosis, ischemic stroke and post-ischemic epilepsy, CNS cancer, addiction, and mental health. These data open up a new path for the potential therapeutic use of the agonist/antagonist of these proteins in the management of several central nervous system diseases.
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Affiliation(s)
- Ciro De Luca
- Laboratory of Neuronal Networks, University of Campania "Luigi Vanvitelli", 80138 Naples, Italy.
| | - Assunta Virtuoso
- Laboratory of Neuronal Networks, University of Campania "Luigi Vanvitelli", 80138 Naples, Italy.
| | - Nicola Maggio
- Department of Neurology, The Chaim Sheba Medical Center, Tel Hashomer, 52621 Ramat Gan, Israel.
- Department of Neurology and Neurosurgery, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 6997801 Tel Aviv, Israel.
| | - Michele Papa
- Laboratory of Neuronal Networks, University of Campania "Luigi Vanvitelli", 80138 Naples, Italy.
- SYSBIO, Centre of Systems Biology, University of Milano-Bicocca, 20126 Milano, Italy.
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