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Studying protein structure and interactions by structural mass spectrometry
Portašiková, Jasmína Mária ; Man, Petr (advisor) ; Vrbacký, Marek (referee)
Transmembrane channels and transporters of the ClC protein family are present across all living organisms. They are found on the cytoplasmic and lysosomal membranes of the cells, where they participate in maintaining ion homeostasis. When dysfuncional, they lead to serious health complications. To develop treatment for these diseases, it is essential to describe transport mechanism of ClC proteins. The antiporter ClC-ec1 from E.coli is used as a model protein for the entire ClC protein family. This homodimeric protein, which transports one proton against two chloride ions, has a separate transport path in each monomer. Based on the crystal structure, it is believed that during transport the protein alternates between outward and inward-facing conformations. Conversion to the outward-facing conformation of the protein is accompanied by the protonation of three glutamates located in the transport path. To study these conditions, a QQQ mutant was designed that has these glutamates replaced by glutamines. Until now, the study of the transport mechanism of ClC-ec1 has mainly relied on studies based on X-ray crystallography. Crystallography provided static images, which did not contain sufficient information about protein dynamics. Therefore, to study transport mechanism of ClC-ec1, we chose a dynamic...
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Detection of subpopulation-specific neuronal membrane molecules using single-cell expression data
Zátko, Matěj ; Modrák, Martin (advisor) ; Kubovčiak, Jan (referee)
Single-cell RNA sequencing is a powerful technology that allows the investigation of gene expression at an unprecedented level. Insights into gene expression in individual cells can help biologists uncover cellular heterogeneity and identify previously unknown cell types. Here, we use single-cell RNA sequencing datasets that reveal subtypes of mouse neurons to find population-specific membrane proteins. These proteins could potentially serve as entry points for targeted drug distribution, allowing for drugs to act only on se- lected neuronal populations. We start by identifying five suitable single-cell mouse neuron datasets. Next, we present an overview and a comparison of currently available methods for differential gene expression analysis, an approach that involves quantifying variations in gene expression between groups and/or conditions, based on previous benchmarks. Lastly, we apply the Wilcoxon rank-sum test to selected datasets in order to identify population-specific membrane proteins. 1
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Molecular dynamics simulations of membrane proteins
Španěl, David ; Barvík, Ivan (advisor) ; Bok, Jiří (referee)
Basic facts about the structure of biomolecules and algorithms applied in molecular dynamics (MD) simulations were recapitulated in the theoretical part of this thesis. A program for MD simulations of a periodic box with water molecules represented by various models (SPC, TIPS, TIP3P) was developed for active mastery of basic algorithms applied in MD simulations. MD simulation methodology was subsequently applied to the structure of the membrane protein A2AGPCR anchored in the phospholipid bilayer and surrounded by water molecules (approx. 120,000 atoms altogether). The purpose of these MD simulations was to compare binding of the natural agonist (adenosine) and its synthetic analog NECA into the binding pocket situated on the extracellular side of A2AGPCR. For these MD simulations were used software package NAMD and computer cluster Gram (in which each node is equipped with 16 CPU cores and 4 GPU) in supercomputing MetaCentrum. Powered by TCPDF (www.tcpdf.org)
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Studies on interactions between NKR-P1D and Clrb membrane receptors
Hanč, Pavel ; Novák, Petr (advisor) ; Brdička, Tomáš (referee)
Studies on interactions between NKR-P1D and Clrb membrane receptors Interaction between murine NKR-P1D and Clrb receptors was originally described as a novel type of "MHC class-I independent missing-self recognition" and was shown to confer protection from killing by natural killer cells.[1] However, further study brought conflicting results suggesting that NKR-P1D does not binds Clrb strongly if it does at all.[2] In order to address the issues arising from these conflicting results, we have recombinantly expressed the extracellular domains of both receptors in E. coli cells and refolded the proteins in vitro. The quality of refolding was confirmed both by determining the disulphide bonding pattern using FTMS and measuring 1 H/15 N-HSQC spectra. By means of size exclusion chromatography and analytical ultracentrifuge we were unable to provide convincing results for the interaction itself. However, using SPR technique, a weak, specific, pH-dependent interaction was observed. Interaction between the proteins in solution was immobilized using chemical cross-linking technique. Three cross-linking reagents, EDC, DSG and DSS were used. The reaction mixture was separated by means of SDS-PAGE and protein bands corresponding to dimers were digested in gel. Using FT-MS we were able to find peptides from both...
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Modeling of an influence of a phospholipid membrane composition on the structure and dynamics of cytochromes P450s.
Gücklhorn, David ; Jeřábek, Petr (advisor) ; Kulhánek, Petr (referee)
Cytochrome P450 1A2 is one the most important enzymes that take part in phase I of biotransformation of xenobiotics in human body. This enzyme is anchored in membrane via transmembrane α-helix. Composition of the phospholipid membrane can affect structure and dynamics of this enzyme. In this thesis optimized full-length all-atom model of cytochrome P450 1A2 in POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) membrane was created based on crystal structure of catalytic domain of this enzyme. Methods of molecular dynamics were used for creation and optimization of the model which contained parts with unknown structure. The optimized model was subjected to thorough analysis of its structure and dynamics and compared to a similar model with DLPC (1,2-dilauroyl-sn-glycero-3- phosphocholine) membrane. The results show that the composition of the membrane significantly affects dynamics of transmembrane domain and its contact with catalytic domain. Usage of the thicker POPC membrane resulted in smaller contact between both domains which caused partial emergence of the catalytic domain from membrane. Penetration of palmitoyl chain of POPC into tunnel 2f was observed in one the trajectories. Analysis of pathways to active site of cytochrome P450 1A2 and the influence of the membrane composition on...
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Molecular dynamics simulations of the muscarinic receptor
Cajzl, Radim ; Barvík, Ivan (advisor) ; Pospíšil, Miroslav (referee)
Title: Molecular dynamics simulations of the muscarinic receptor Author: Radim Cajzl Department: Institute of Physics of Charles University Supervisor: RNDr. Ivan Barvík, Ph.D., Division of Biomolecular Physics Abstract: This thesis is devoted to molecular dynamics simulations of the mus- carinic M2 receptor placed in a phospholipidic membrane. Basic algorithms of molecular dynamics are described and applied on a simple model of rare gases. Relations for calculation of binding free energies are derived. Several tricks for sa- ving up computational time are presented. Next part contains a brief description of proteins and cellular membranes, structure and biological relevance of musca- rinic receptors and known crystal structures of the muscarinic M2 receptor. The chapter with results contains detailed description of calculations of bin- ding free energy differences for several ligands bound to the muscarinic M2 recep- tor. Obtained values match the experimental ones. Dynamics of the muscarinic M2 receptor was also studied yielding a direction for future studies of the acti- vation mechanism. Short discussion on application of obtained results in rational drug design can be found in the Conclusion chapter. Keywords: molecular dynamics, membrane proteins, free energy perturbation, muscarinic receptor,...
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Molecular dynamics simulations of membrane proteins
Španěl, David ; Barvík, Ivan (advisor) ; Bok, Jiří (referee)
Basic facts about the structure of biomolecules and algorithms applied in molecular dynamics (MD) simulations were recapitulated in the theoretical part of this thesis. A program for MD simulations of a periodic box with water molecules represented by various models (SPC, TIPS, TIP3P) was developed for active mastery of basic algorithms applied in MD simulations. MD simulation methodology was subsequently applied to the structure of the membrane protein A2AGPCR anchored in the phospholipid bilayer and surrounded by water molecules (approx. 120,000 atoms altogether). The purpose of these MD simulations was to compare binding of the natural agonist (adenosine) and its synthetic analog NECA into the binding pocket situated on the extracellular side of A2AGPCR. For these MD simulations were used software package NAMD and computer cluster Gram (in which each node is equipped with 16 CPU cores and 4 GPU) in supercomputing MetaCentrum. Powered by TCPDF (www.tcpdf.org)
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Studies on interactions between NKR-P1D and Clrb membrane receptors
Hanč, Pavel ; Novák, Petr (advisor) ; Brdička, Tomáš (referee)
Studies on interactions between NKR-P1D and Clrb membrane receptors Interaction between murine NKR-P1D and Clrb receptors was originally described as a novel type of "MHC class-I independent missing-self recognition" and was shown to confer protection from killing by natural killer cells.[1] However, further study brought conflicting results suggesting that NKR-P1D does not binds Clrb strongly if it does at all.[2] In order to address the issues arising from these conflicting results, we have recombinantly expressed the extracellular domains of both receptors in E. coli cells and refolded the proteins in vitro. The quality of refolding was confirmed both by determining the disulphide bonding pattern using FTMS and measuring 1 H/15 N-HSQC spectra. By means of size exclusion chromatography and analytical ultracentrifuge we were unable to provide convincing results for the interaction itself. However, using SPR technique, a weak, specific, pH-dependent interaction was observed. Interaction between the proteins in solution was immobilized using chemical cross-linking technique. Three cross-linking reagents, EDC, DSG and DSS were used. The reaction mixture was separated by means of SDS-PAGE and protein bands corresponding to dimers were digested in gel. Using FT-MS we were able to find peptides from both...
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