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In silico design and validation of conotoxin-based peptides for neuroblastoma nanotherapy
Mokrý, Michal ; Gumulec, Jaromír (referee) ; Heger, Zbyněk (advisor)
Práca sa zaoberá in silico dizajnom a validáciou peptidov založených na konotoxíne - MrIA, izolovaného z morských slimákov druhu Conus marmoreus a možnosti využitia týchto peptidov v liečbe neuroblastómu pomocou cielenia norepinefrínového transportéru. Päť peptidov založených na tomto konotoxíne bolo simulovaných pomocou simulácii molekulárnej dynamiky, ich trajektórie boli analyzované pre zistenie vlastností týchto peptidov. Dva homologické modely ľudského norepinefrínového transportéru boli vytvorené pre analýzu väzobných vlastností peptidov založených na konotoxíne ku norepinefrínovému transportéru. Peptidy boli následne syntetizované a použité na pokrytie apoferitínových nanočastíc s elipticínom uväzneným vnútri apoferitínu. Vytvorené peptidy a nanočastice boli ďalej skúmané pre objasnenie ich fyzikálo-chemických vlastností. Interakcie a cytotoxicita boli skúmané aplokáciou nanočastíc na bunky neuroblastómu a epitelu. Z in silico a in vitro analýz vyšiel YKL-6 peptid ako najlepší kandidát na ďalší výskum.
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Mechanism of retrograde transport in contact-dependent inhibition (CDI) toxins through the bacterial translocon
KRUGLHUBER, Anna
Amongst bacteria, living in complex and varying communities and surroundings, rivalry for crucial resources exists. Due to the constant pressure, strategies to allow competition and communication have been developed within bacterial communities. In this respect, Contact Dependent Growth Inhibition (CDI) is often of relevance. The aim was to elucidate a newly found pathway of transport of the CDI toxins across the inner bacterial membrane via Sec translocon. Since all proteins are transported via Sec translocon in an unfolded state, and there is no obvious mechanism which would drive or facilitate this transport in the retrograde fashion, the hypothesis that the effector domain of CDI toxins evolved an anisotropic energy landscape of mechanical unfolding was constructed. That would allow the toxin to be mechanically more labile in the direction of translocation and mechanically stable in the orthogonal directions. This anisotropy would permit efficient translocation and overall thermodynamic stability at the same time. The unfolding landscape was assessed by a molecular dynamics simulation combined with umbrella sampling. Developed methodology, complemented with a rational design of "circular permutants", helped to estimate the forces required to unfold the toxins under different geometries.
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Molecular dynamics simulations of biomolecular complexes consisting of proteins and nucleic acids
Melcr, Josef ; Barvík, Ivan (advisor) ; Bok, Jiří (referee)
Literature search on the Elongation factor Tu (EF-Tu), which is involved in the process of translation of genetic information, was performed. Further, computational methods as molecular dynamics (MD) and Monte Carlo (MC) were studied. Then, computer programs for MD and MC simulations of a Lennard-Jones gas were developed. MD simulations were further applied to EF-Tu using the NAMD and ACEMD software packages. Multiprocessor PC clusters and programmable NVIDIA GPUs were used. MD simulations of EF-Tu uncovered binding of monovalent ions in nearby of the EF-Tu active site. The impact of Na$^+$ binding on evolutionarily conserved residues (His85, Val20, Ile61, Asp21, Tyr47, Asp87, etc.) was studied in detail.
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In silico design and validation of conotoxin-based peptides for neuroblastoma nanotherapy
Mokrý, Michal ; Gumulec, Jaromír (referee) ; Heger, Zbyněk (advisor)
Práca sa zaoberá in silico dizajnom a validáciou peptidov založených na konotoxíne - MrIA, izolovaného z morských slimákov druhu Conus marmoreus a možnosti využitia týchto peptidov v liečbe neuroblastómu pomocou cielenia norepinefrínového transportéru. Päť peptidov založených na tomto konotoxíne bolo simulovaných pomocou simulácii molekulárnej dynamiky, ich trajektórie boli analyzované pre zistenie vlastností týchto peptidov. Dva homologické modely ľudského norepinefrínového transportéru boli vytvorené pre analýzu väzobných vlastností peptidov založených na konotoxíne ku norepinefrínovému transportéru. Peptidy boli následne syntetizované a použité na pokrytie apoferitínových nanočastíc s elipticínom uväzneným vnútri apoferitínu. Vytvorené peptidy a nanočastice boli ďalej skúmané pre objasnenie ich fyzikálo-chemických vlastností. Interakcie a cytotoxicita boli skúmané aplokáciou nanočastíc na bunky neuroblastómu a epitelu. Z in silico a in vitro analýz vyšiel YKL-6 peptid ako najlepší kandidát na ďalší výskum.
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Simulation of processes in cellular membranes
Melcr, Josef ; Jungwirth, Pavel (advisor)
Simulation of processes in cellular membranes Abstract Many important processes in cells involve ions, e.g., fusion of synaptic vesi- cles with neuronal cell membranes is controlled by a divalent cation Ca2+ ; and the exchange of Na+ and K+ drives the the fast electrical signal transmis- sion in neurons. We have investigated model phospholipid membranes and their interactions with these biologically relevant ions. Using state-of-the-art molecular dynamics simulations, we accurately quantified their respective affinites towards neutral and negatively charged phospholipid bilayers. In order to achieve that, we developed a new model of phospholipids termed ECC-lipids, which accounts for the electronic polarization via the electronic continuum correction implemented as charge rescaling. Our simulations with this new force field reach for the first time a quantitative agreement with the experimental lipid electrometer concept for POPC as well as for POPS with all the studied cations. We have also examined the effects of transmembrane voltage on phospholipid bilayers. The electric field induced by the voltage exists exclusively in the hydrophobic region of the membrane, where it has an almost constant strength. This field affects the structure of nearby water molecules highlighting its importance in electroporation. 1
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Simulation of processes in cellular membranes
Melcr, Josef ; Jungwirth, Pavel (advisor)
Simulation of processes in cellular membranes Abstract Many important processes in cells involve ions, e.g., fusion of synaptic vesi- cles with neuronal cell membranes is controlled by a divalent cation Ca2+ ; and the exchange of Na+ and K+ drives the the fast electrical signal transmis- sion in neurons. We have investigated model phospholipid membranes and their interactions with these biologically relevant ions. Using state-of-the-art molecular dynamics simulations, we accurately quantified their respective affinites towards neutral and negatively charged phospholipid bilayers. In order to achieve that, we developed a new model of phospholipids termed ECC-lipids, which accounts for the electronic polarization via the electronic continuum correction implemented as charge rescaling. Our simulations with this new force field reach for the first time a quantitative agreement with the experimental lipid electrometer concept for POPC as well as for POPS with all the studied cations. We have also examined the effects of transmembrane voltage on phospholipid bilayers. The electric field induced by the voltage exists exclusively in the hydrophobic region of the membrane, where it has an almost constant strength. This field affects the structure of nearby water molecules highlighting its importance in electroporation. 1
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Simulation of processes in cellular membranes
Melcr, Josef ; Jungwirth, Pavel (advisor) ; Otyepka, Michal (referee) ; Tarek, Mounir (referee)
Simulation of processes in cellular membranes Abstract Many important processes in cells involve ions, e.g., fusion of synaptic vesi- cles with neuronal cell membranes is controlled by a divalent cation Ca2+ ; and the exchange of Na+ and K+ drives the the fast electrical signal transmis- sion in neurons. We have investigated model phospholipid membranes and their interactions with these biologically relevant ions. Using state-of-the-art molecular dynamics simulations, we accurately quantified their respective affinites towards neutral and negatively charged phospholipid bilayers. In order to achieve that, we developed a new model of phospholipids termed ECC-lipids, which accounts for the electronic polarization via the electronic continuum correction implemented as charge rescaling. Our simulations with this new force field reach for the first time a quantitative agreement with the experimental lipid electrometer concept for POPC as well as for POPS with all the studied cations. We have also examined the effects of transmembrane voltage on phospholipid bilayers. The electric field induced by the voltage exists exclusively in the hydrophobic region of the membrane, where it has an almost constant strength. This field affects the structure of nearby water molecules highlighting its importance in electroporation. 1
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Determination of the structure of pore-forming colicins
Riedlová, Kamila ; Fišer, Radovan (advisor) ; Barvík, Ivan (referee)
6 Abstract This master's thesis provides study of individual helixes from C-terminal pore-forming domain (CTD) of colicin U and their behavior in lipid bilayer on atomic level. For this purpose the all-atom molecular simulation method was used. Later the study was extended an applied on CTD of published structures of other pore-forming colicins. On the base of study extension the ability of disruption of lipid bilayer integrity by helixes H1 and H10 was successfully observed. Helix H1 was synthesized and its activity was experimentally proved on black lipid membranes. The other helixes are often too short to be able to keep position in lipid bilayer and their behavior could be affected by artificial termini, therefore they were not synthesized. The MD simulations of pairs of helixes show that structure stability and their ability to stay in the membrane depends on binding partners. The results of the thesis show the importance of H10 for colicin pore-formation, which has not been observed yet. The results also support the toroidal pore model suggested previously for colicin E1. The results prove that colicins contain specific secondary structures, which are able to disrupt the inner bacterial membrane not only in its native form but also when artificially separated from the rest of the protein. Klíčová...
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Modelling mechanical properties of RNA and DNA
Dršata, Tomáš ; Lankaš, Filip (advisor) ; Banáš, Pavel (referee) ; Schneider, Bohdan (referee)
Structural and mechanical properties of nucleic acids play a key role in a wide range of biological processes, as well as in the field of nucleic acid nanotechnology. The thesis presents results of several studies focused on modelling these properties. Extensive unrestrained atomic-resolution molecular dynamics (MD) simulations are used to investigate structural dynamics of nucleic acids, and to parametrize their mechanical models. The deformation energy is assumed to be a general quadratic function of suitably chosen internal coordinates. Two types of models are employed which differ in the level of coarse- graining. The first one is based on the description of conformation at the level of individual bases and the second, coarser one is used to study global bending and twisting flexibility. The models are applied to explain mechanical properties of A-tracts in the context of DNA looping and nucleosome positioning, to characterize twist-stretch cou- pled deformations in DNA and RNA, and to predict changes in the properties of damaged DNA that are likely to be relevant for damage recognition and repair. Besides that, we propose a general model of DNA allostery, applied to study the effect of minor groove binding of small ligands and the allosteric coupling between proteins mediated by the DNA. A careful...
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Molecular dynamics simulations of biomolecular complexes consisting of proteins and nucleic acids
Melcr, Josef ; Barvík, Ivan (advisor) ; Bok, Jiří (referee)
Literature search on the Elongation factor Tu (EF-Tu), which is involved in the process of translation of genetic information, was performed. Further, computational methods as molecular dynamics (MD) and Monte Carlo (MC) were studied. Then, computer programs for MD and MC simulations of a Lennard-Jones gas were developed. MD simulations were further applied to EF-Tu using the NAMD and ACEMD software packages. Multiprocessor PC clusters and programmable NVIDIA GPUs were used. MD simulations of EF-Tu uncovered binding of monovalent ions in nearby of the EF-Tu active site. The impact of Na$^+$ binding on evolutionarily conserved residues (His85, Val20, Ile61, Asp21, Tyr47, Asp87, etc.) was studied in detail.
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