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  1. Article ; Online: Fine tuning rigid body docking results using the Dreiding force field: A computational study of 36 known nanobody-protein complexes.

    Hacisuleyman, Aysima / Erman, Burak

    Proteins

    2023  Volume 91, Issue 10, Page(s) 1417–1426

    Abstract: This paper aims to understand the binding strategies of a nanobody-protein pair by studying known complexes. Rigid body protein-ligand docking programs produce several complexes, called decoys, which are good candidates with high scores of shape ... ...

    Abstract This paper aims to understand the binding strategies of a nanobody-protein pair by studying known complexes. Rigid body protein-ligand docking programs produce several complexes, called decoys, which are good candidates with high scores of shape complementarity, electrostatic interactions, desolvation, buried surface area, and Lennard-Jones potentials. However, the decoy that corresponds to the native structure is not known. We studied 36 nanobody-protein complexes from the single domain antibody database, sd-Ab DB, http://www.sdab-db.ca/. For each structure, a large number of decoys are generated using the Fast Fourier Transform algorithm of the software ZDOCK. The decoys were ranked according to their target protein-nanobody interaction energies, calculated by using the Dreiding Force Field, with rank 1 having the lowest interaction energy. Out of 36 protein data bank (PDB) structures, 25 true structures were predicted as rank 1. Eleven of the remaining structures required Ångstrom size rigid body translations of the nanobody relative to the protein to match the given PDB structure. After the translation, the Dreiding interaction (DI) energies of all complexes decreased and became rank 1. In one case, rigid body rotations as well as translations of the nanobody were required for matching the crystal structure. We used a Monte Carlo algorithm that randomly translates and rotates the nanobody of a decoy and calculates the DI energy. Results show that rigid body translations and the DI energy are sufficient for determining the correct binding location and pose of ZDOCK created decoys. A survey of the sd-Ab DB showed that each nanobody makes at least one salt bridge with its partner protein, indicating that salt bridge formation is an essential strategy in nanobody-protein recognition. Based on the analysis of the 36 crystal structures and evidence from existing literature, we propose a set of principles that could be used in the design of nanobodies.
    MeSH term(s) Protein Binding ; Proteins/chemistry ; Software ; Algorithms ; Fourier Analysis ; Protein Conformation
    Chemical Substances Proteins
    Language English
    Publishing date 2023-05-26
    Publishing country United States
    Document type Journal Article
    ZDB-ID 806683-8
    ISSN 1097-0134 ; 0887-3585
    ISSN (online) 1097-0134
    ISSN 0887-3585
    DOI 10.1002/prot.26529
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Synergy and anti-cooperativity in allostery: Molecular dynamics study of WT and oncogenic KRAS-RGL1.

    Hacisuleyman, Aysima / Erman, Burak

    Proteins

    2023  Volume 92, Issue 5, Page(s) 665–678

    Abstract: This study focuses on investigating the effects of an oncogenic mutation (G12V) on the stability and interactions within the KRAS-RGL1 protein complex. The KRAS-RGL1 complex is of particular interest due to its relevance to KRAS-associated cancers and ... ...

    Abstract This study focuses on investigating the effects of an oncogenic mutation (G12V) on the stability and interactions within the KRAS-RGL1 protein complex. The KRAS-RGL1 complex is of particular interest due to its relevance to KRAS-associated cancers and the potential for developing targeted drugs against the KRAS system. The stability of the complex and the allosteric effects of specific residues are examined to understand their roles as modulators of complex stability and function. Using molecular dynamics simulations, we calculate the mutual information, MI, between two neighboring residues at the interface of the KRAS-RGL1 complex, and employ the concept of interaction information, II, to measure the contribution of a third residue to the interaction between interface residue pairs. Negative II indicates synergy, where the presence of the third residue strengthens the interaction, while positive II suggests anti-cooperativity. Our findings reveal that MI serves as a dominant factor in determining the results, with the G12V mutation increasing the MI between interface residues, indicating enhanced correlations due to the formation of a more compact structure in the complex. Interestingly, although II plays a role in understanding three-body interactions and the impact of distant residues, it is not significant enough to outweigh the influence of MI in determining the overall stability of the complex. Nevertheless, II may nonetheless be a relevant factor to consider in future drug design efforts. This study provides valuable insights into the mechanisms of complex stability and function, highlighting the significance of three-body interactions and the impact of distant residues on the binding stability of the complex. Additionally, our findings demonstrate that constraining the fluctuations of a third residue consistently increases the stability of the G12V variant, making it challenging to weaken complex formation of the mutated species through allosteric manipulation. The novel perspective offered by this approach on protein dynamics, function, and allostery has potential implications for understanding and targeting other protein complexes involved in vital cellular processes. The results contribute to our understanding of the effects of oncogenic mutations on protein-protein interactions and provide a foundation for future therapeutic interventions in the context of KRAS-associated cancers and beyond.
    MeSH term(s) Humans ; Molecular Dynamics Simulation ; Proto-Oncogene Proteins p21(ras)/genetics ; Mutation ; Neoplasms/genetics ; Allosteric Regulation ; Guanine Nucleotide Exchange Factors
    Chemical Substances Proto-Oncogene Proteins p21(ras) (EC 3.6.5.2) ; KRAS protein, human ; RGL1 protein, human ; Guanine Nucleotide Exchange Factors
    Language English
    Publishing date 2023-12-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 806683-8
    ISSN 1097-0134 ; 0887-3585
    ISSN (online) 1097-0134
    ISSN 0887-3585
    DOI 10.1002/prot.26657
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  3. Article ; Online: Information flow and allosteric communication in proteins.

    Hacisuleyman, Aysima / Erman, Burak

    The Journal of chemical physics

    2022  Volume 156, Issue 18, Page(s) 185101

    Abstract: Based on Schreiber's work on transfer entropy, a molecular theory of nonlinear information transfer between residue pairs in proteins is developed. The joint distribution function for residue fluctuations required by the theory is expressed in terms of ... ...

    Abstract Based on Schreiber's work on transfer entropy, a molecular theory of nonlinear information transfer between residue pairs in proteins is developed. The joint distribution function for residue fluctuations required by the theory is expressed in terms of tensor Hermite polynomials that conveniently separate harmonic and nonlinear contributions to information transfer. The harmonic part of information transfer is expressed as the difference between time dependent and independent mutual information. Third order nonlinearities are discussed in detail. The amount and speed of information transfer between residues, which are important for understanding allosteric activity in proteins, are discussed. Mutual information between two residues is commonly used for information transfer. While mutual information shows the maximum amount of information that may be transferred between two residues, it does not explain the actual amount of transfer nor the transfer rate of information. For this, dynamic equations of the system are needed. The solution of the Langevin equation and molecular dynamics trajectories are used in the present work for this purpose. Allosteric communication in human NAD-dependent isocitrate dehydrogenase is studied as an example. Calculations show that several paths contribute collectively to information transfer. Important residues on these paths are identified. Time resolved information transfer between these residues, their amplitudes, and transfer rates, which are in agreement with time resolved ultraviolet resonance Raman measurements in general, are estimated. Peak values of calculated information transfer, ∼0.01-0.04 bits, are about two orders of magnitude smaller than the information content of residues. They are comparable to mutual information values, however. Estimated transfer rates are in the order of 1-20 megabits per second, and sustained transfer during the activity time-span of proteins may be significant. Information transfer from third order contributions is one to two orders of magnitude smaller than the harmonic terms, showing that harmonic analysis is a good approximation to information transfer.
    MeSH term(s) Communication ; Entropy ; Humans ; Molecular Dynamics Simulation ; Proteins/chemistry
    Chemical Substances Proteins
    Language English
    Publishing date 2022-05-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/5.0088522
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  4. Article ; Online: Prediction of allosteric communication pathways in proteins.

    Haliloglu, Turkan / Hacisuleyman, Aysima / Erman, Burak

    Bioinformatics (Oxford, England)

    2022  Volume 38, Issue 14, Page(s) 3590–3599

    Abstract: Motivation: Allostery in proteins is an essential phenomenon in biological processes. In this article, we present a computational model to predict paths of maximum information transfer between active and allosteric sites. In this information theoretic ... ...

    Abstract Motivation: Allostery in proteins is an essential phenomenon in biological processes. In this article, we present a computational model to predict paths of maximum information transfer between active and allosteric sites. In this information theoretic study, we use mutual information as the measure of information transfer, where transition probability of information from one residue to its contacting neighbors is proportional to the magnitude of mutual information between the two residues. Starting from a given residue and using a Hidden Markov Model, we successively determine the neighboring residues that eventually lead to a path of optimum information transfer. The Gaussian approximation of mutual information between residue pairs is adopted. The limits of validity of this approximation are discussed in terms of a nonlinear theory of mutual information and its reduction to the Gaussian form.
    Results: Predictions of the model are tested on six widely studied cases, CheY Bacterial Chemotaxis, B-cell Lymphoma extra-large (Bcl-xL), Human proline isomerase cyclophilin A (CypA), Dihydrofolate reductase (DHFR), HRas GTPase and Caspase-1. The communication transmission rendering the propagation of local fluctuations from the active sites throughout the structure in multiple paths correlate well with the known experimental data. Distinct paths originating from the active site may likely represent a multi functionality such as involving more than one allosteric site and/or pre-existence of some other functional states. Our model is computationally fast and simple and can give allosteric communication pathways, which are crucial for the understanding and control of protein functionality.
    Supplementary information: Supplementary data are available at Bioinformatics online.
    MeSH term(s) Humans ; Allosteric Regulation ; Allosteric Site ; Proteins/chemistry ; Catalytic Domain ; Communication
    Chemical Substances Proteins
    Language English
    Publishing date 2022-06-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 1422668-6
    ISSN 1367-4811 ; 1367-4803
    ISSN (online) 1367-4811
    ISSN 1367-4803
    DOI 10.1093/bioinformatics/btac380
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  5. Article ; Online: ModiBodies: A computational method for modifying nanobodies in nanobody-antigen complexes to improve binding affinity and specificity.

    Hacisuleyman, Aysima / Erman, Burak

    Journal of biological physics

    2020  Volume 46, Issue 2, Page(s) 189–208

    Abstract: Nanobodies are special derivatives of antibodies, which consist of single domain fragments. They have become of considerable interest as next-generation biotechnological tools for antigen recognition. They can be easily engineered due to their high ... ...

    Abstract Nanobodies are special derivatives of antibodies, which consist of single domain fragments. They have become of considerable interest as next-generation biotechnological tools for antigen recognition. They can be easily engineered due to their high stability and compact size. Nanobodies have three complementarity-determining regions, CDRs, which are enlarged to provide a similar binding surface to that of human immunoglobulins. Here, we propose a benchmark testing algorithm that uses 3D structures of already existing protein-nanobody complexes as initial structures followed by successive mutations on the CDR domains. The aim is to find optimum binding amino acids for hypervariable residues of CDRs. We use molecular dynamics simulations to compare the binding energies of the resulting complexes with that of the known complex and accept those that are improved by mutations. We use the MDM4-VH9 complex, (PDB id 2VYR), fructose-bisphosphate aldolase from Trypanosoma congolense (PDB id 5O0W) and human lysozyme (PDB id 4I0C) as benchmark complexes. By using this algorithm, better binding nanobodies can be generated in a short amount of time. We suggest that this method can complement existing immune and synthetic library-based methods, without a need for extensive experimentation or large libraries.
    MeSH term(s) Antibody Specificity ; Humans ; Molecular Dynamics Simulation ; Protein Conformation ; Single-Domain Antibodies/chemistry ; Single-Domain Antibodies/immunology
    Chemical Substances Single-Domain Antibodies
    Language English
    Publishing date 2020-05-16
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2016734-9
    ISSN 1573-0689 ; 0092-0606
    ISSN (online) 1573-0689
    ISSN 0092-0606
    DOI 10.1007/s10867-020-09548-3
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  6. Article ; Online: Synchronous and Asynchronous Response in Dynamically Perturbed Proteins.

    Hacisuleyman, Aysima / Erkip, Albert / Erman, Batu / Erman, Burak

    The journal of physical chemistry. B

    2021  Volume 125, Issue 3, Page(s) 729–739

    Abstract: We present a dynamic perturbation-response model of proteins based on the Gaussian Network Model, where a residue is perturbed periodically, and the dynamic response of other residues is determined. The model shows that periodic perturbation causes a ... ...

    Abstract We present a dynamic perturbation-response model of proteins based on the Gaussian Network Model, where a residue is perturbed periodically, and the dynamic response of other residues is determined. The model shows that periodic perturbation causes a synchronous response in phase with the perturbation and an asynchronous response that is out of phase. The asynchronous component results from the viscous effects of the solvent and other dispersive factors in the system. The model is based on the solution of the Langevin equation in the presence of solvent, noise, and perturbation. We introduce several novel ideas: The concept of storage and loss compliance of the protein and their dependence on structure and frequency; the amount of work lost and the residues that contribute significantly to the lost work; new dynamic correlations that result from perturbation; causality, that is, the response of j when i is perturbed is not equal to the response of i when j is perturbed. As examples, we study two systems, namely, bovine rhodopsin and the class of nanobodies. The general results obtained are (i) synchronous and asynchronous correlations depend strongly on the frequency of perturbation, their magnitude decreases with increasing frequency, (ii) time-delayed mean-squared fluctuations of residues have only synchronous components. Asynchronicity is present only in cross correlations, that is, correlations between different residues, (iii) perturbation of loop residues leads to a large dissipation of work, (iv) correlations satisfy the hypothesis of pre-existing pathways according to which information transfer by perturbation rides on already existing equilibrium correlations in the system, (v) dynamic perturbation can introduce a selective response in the system, where the perturbation of each residue excites different sets of responding residues, and (vi) it is possible to identify nondissipative residues whose perturbation does not lead to dissipation in the protein. Despite its simplicity, the model explains several features of allosteric manipulation.
    MeSH term(s) Animals ; Cattle ; Normal Distribution ; Proteins
    Chemical Substances Proteins
    Language English
    Publishing date 2021-01-19
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5207
    ISSN (online) 1520-5207
    DOI 10.1021/acs.jpcb.0c08409
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  7. Article ; Online: Binding Mechanism of Neutralizing Nanobodies Targeting SARS-CoV-2 Spike Glycoprotein.

    Golcuk, Mert / Hacisuleyman, Aysima / Erman, Burak / Yildiz, Ahmet / Gur, Mert

    Journal of chemical information and modeling

    2021  Volume 61, Issue 10, Page(s) 5152–5160

    Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters human cells upon binding of its spike (S) glycoproteins to ACE2 receptors. Several nanobodies neutralize SARS-CoV-2 infection by binding to the receptor-binding domain (RBD) of the S ... ...

    Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters human cells upon binding of its spike (S) glycoproteins to ACE2 receptors. Several nanobodies neutralize SARS-CoV-2 infection by binding to the receptor-binding domain (RBD) of the S protein, but how their binding antagonizes S-ACE2 interactions is not well understood. Here, we identified interactions between the RBD and nanobodies H11-H4, H11-D4, and Ty1 by performing all-atom molecular dynamics simulations. H11-H4 and H11-D4 can bind to RBD without overlapping with ACE2. H11-H4, and to a lesser extent H11-D4, binding dislocates ACE2 from its binding site due to electrostatic repulsion. In comparison, Ty1 overlaps with ACE2 on RBD and has a similar binding strength to ACE2. Mutations in the Alpha variant of SARS-CoV-2 had a minor effect in RBD binding strengths of ACE2 and nanobodies, but reduced the ability of H11-H4 and H11-D4 to dislocate ACE2 from RBD. In comparison, the Beta variant weakened the RBD binding strengths of H11-H4 and H11-D4, which were less effective to dislocate ACE2 binding. Unexpectedly, mutations in Beta strengthened Ty1 binding to RBD, suggesting that this nanobody may be more effective to neutralize the Beta variant of SARS-CoV-2.
    MeSH term(s) Antibodies, Neutralizing/immunology ; Antibodies, Viral/immunology ; Binding Sites ; COVID-19 ; Humans ; Protein Binding ; SARS-CoV-2 ; Single-Domain Antibodies/immunology ; Spike Glycoprotein, Coronavirus/immunology
    Chemical Substances Antibodies, Neutralizing ; Antibodies, Viral ; Single-Domain Antibodies ; Spike Glycoprotein, Coronavirus ; spike protein, SARS-CoV-2
    Language English
    Publishing date 2021-09-28
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 190019-5
    ISSN 1549-960X ; 0095-2338
    ISSN (online) 1549-960X
    ISSN 0095-2338
    DOI 10.1021/acs.jcim.1c00695
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  8. Article ; Online: SARS-CoV-2 Delta Variant Decreases Nanobody Binding and ACE2 Blocking Effectivity.

    Golcuk, Mert / Hacisuleyman, Aysima / Yilmaz, Sema Zeynep / Taka, Elhan / Yildiz, Ahmet / Gur, Mert

    Journal of chemical information and modeling

    2022  Volume 62, Issue 10, Page(s) 2490–2498

    Abstract: The Delta variant spreads more rapidly than previous variants of SARS-CoV-2. This variant comprises several mutations on the receptor-binding domain ( ... ...

    Abstract The Delta variant spreads more rapidly than previous variants of SARS-CoV-2. This variant comprises several mutations on the receptor-binding domain (RBD
    MeSH term(s) Angiotensin-Converting Enzyme 2 ; COVID-19/drug therapy ; Humans ; Molecular Dynamics Simulation ; Protein Binding ; SARS-CoV-2 ; Single-Domain Antibodies/metabolism ; Spike Glycoprotein, Coronavirus/genetics ; Spike Glycoprotein, Coronavirus/metabolism
    Chemical Substances Single-Domain Antibodies ; Spike Glycoprotein, Coronavirus ; spike protein, SARS-CoV-2 ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23)
    Language English
    Publishing date 2022-05-09
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 190019-5
    ISSN 1549-960X ; 0095-2338
    ISSN (online) 1549-960X
    ISSN 0095-2338
    DOI 10.1021/acs.jcim.1c01523
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  9. Article ; Online: Entropy Transfer between Residue Pairs and Allostery in Proteins: Quantifying Allosteric Communication in Ubiquitin.

    Hacisuleyman, Aysima / Erman, Burak

    PLoS computational biology

    2017  Volume 13, Issue 1, Page(s) e1005319

    Abstract: It has recently been proposed by Gunasakaran et al. that allostery may be an intrinsic property of all proteins. Here, we develop a computational method that can determine and quantify allosteric activity in any given protein. Based on Schreiber's ... ...

    Abstract It has recently been proposed by Gunasakaran et al. that allostery may be an intrinsic property of all proteins. Here, we develop a computational method that can determine and quantify allosteric activity in any given protein. Based on Schreiber's transfer entropy formulation, our approach leads to an information transfer landscape for the protein that shows the presence of entropy sinks and sources and explains how pairs of residues communicate with each other using entropy transfer. The model can identify the residues that drive the fluctuations of others. We apply the model to Ubiquitin, whose allosteric activity has not been emphasized until recently, and show that there are indeed systematic pathways of entropy and information transfer between residues that correlate well with the activities of the protein. We use 600 nanosecond molecular dynamics trajectories for Ubiquitin and its complex with human polymerase iota and evaluate entropy transfer between all pairs of residues of Ubiquitin and quantify the binding susceptibility changes upon complex formation. We explain the complex formation propensities of Ubiquitin in terms of entropy transfer. Important residues taking part in allosteric communication in Ubiquitin predicted by our approach are in agreement with results of NMR relaxation dispersion experiments. Finally, we show that time delayed correlation of fluctuations of two interacting residues possesses an intrinsic causality that tells which residue controls the interaction and which one is controlled. Our work shows that time delayed correlations, entropy transfer and causality are the required new concepts for explaining allosteric communication in proteins.
    MeSH term(s) Allosteric Site ; Amino Acids/chemistry ; Binding Sites ; Entropy ; Models, Chemical ; Molecular Dynamics Simulation ; Protein Binding ; Protein Conformation ; Structure-Activity Relationship ; Ubiquitin/chemistry ; Ubiquitin/ultrastructure ; Ubiquitination
    Chemical Substances Amino Acids ; Ubiquitin
    Language English
    Publishing date 2017-01-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1005319
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  10. Article ; Online: Causality, transfer entropy, and allosteric communication landscapes in proteins with harmonic interactions.

    Hacisuleyman, Aysima / Erman, Burak

    Proteins

    2017  Volume 85, Issue 6, Page(s) 1056–1064

    Abstract: A fast and approximate method of generating allosteric communication landscapes in proteins is presented by using Schreiber's entropy transfer concept in combination with the Gaussian Network Model of proteins. Predictions of the model and the allosteric ...

    Abstract A fast and approximate method of generating allosteric communication landscapes in proteins is presented by using Schreiber's entropy transfer concept in combination with the Gaussian Network Model of proteins. Predictions of the model and the allosteric communication landscapes generated show that information transfer in proteins does not necessarily take place along a single path, but an ensemble of pathways is possible. The model emphasizes that knowledge of entropy only is not sufficient for determining allosteric communication and additional information based on time delayed correlations should be introduced, which leads to the presence of causality in proteins. The model provides a simple tool for mapping entropy sink-source relations into pairs of residues. By this approach, residues that should be manipulated to control protein activity may be determined. This should be of great importance for allosteric drug design and for understanding the effects of mutations on function. The model is applied to determine allosteric communication in three proteins, Ubiquitin, Pyruvate Kinase, and the PDZ domain. Predictions are in agreement with molecular dynamics simulations and experimental evidence. Proteins 2017; 85:1056-1064. © 2017 Wiley Periodicals, Inc.
    MeSH term(s) Allosteric Regulation ; Allosteric Site ; Entropy ; Humans ; Molecular Dynamics Simulation ; PDZ Domains ; Protein Conformation, alpha-Helical ; Protein Conformation, beta-Strand ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Pyruvate Kinase/chemistry ; Time Factors ; Ubiquitin/chemistry
    Chemical Substances Ubiquitin ; Pyruvate Kinase (EC 2.7.1.40)
    Language English
    Publishing date 2017-03-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 806683-8
    ISSN 1097-0134 ; 0887-3585
    ISSN (online) 1097-0134
    ISSN 0887-3585
    DOI 10.1002/prot.25272
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