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Optimization of recombinant protein expression in HEK293 cell line
Bláha, Jan ; Bezouška, Karel (advisor) ; Šácha, Pavel (referee)
Mammalian cells have become the dominant system for recombinant expression of pharmaceutical proteins. This system is becoming suitable also for structural biology, with the advances in methodology of transient transfection of mammalian cells. This work dealt with optimization of recombinant expression in HEK293T and HEK293-6E cell lines in various media using easily quantifiable markers - secreted alkaline phosphatase (SEAP) and green fluorescent protein (GFP). Emphasis was placed on optimizing key factors behind the creation of transfection complex - the ratio of DNA to polyethyleneimine and the amount of DNA used. The positive influence of histone deacetylases inhibitor valproic acid and also of casein hydrolysate Tryptone N1 was also studied. (The thesis is written in Czech.)
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Multivalent carbohydrate ligands of galectins
Hovorková, Michaela ; Křen, Vladimír (advisor) ; Kavan, Daniel (referee)
Galectins are proteins, wich belong to a group of lectins that are able to bind to saccharide units and they specifically recognize glycans exposed to the surface of the cells. Galectins participate in vivo, for example, in carcinogenesis, angiogenesis or fibrosis. Their occurrence increases significantly in connection with a number of pathogenic processes, therefore they can be used as markers for some types of cancer or cardiopathology and also for the targeted binding of therapeutics and/ or imaging agents in diagnosis and therapy. Galectin-3 has a specific structure known as chimeric and it is capable of forming multivalent oligomers. The natural ligands of galectins are glycans containing terminal β-galactosides, especially N-acetyllactosamine, but the binding of monovalent glycans is very weak. Glycoconjugates with high affinity to galectin receptors are optimally multivalent, biocompatible and stable in vivo. These criteria accomplish carbohydrate ligands conjugated to soluble and structurally flexible N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers. In this work two types of functionalized disaccharides based on N-acetyllactosamine (Galβ4GlcNAc) and its structural analogue of N,N'-diacetyllactosamine (GalNAcβ4GlcNAc) was prepared by enzymatic synthesis. For the synthesis were used...
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Recombinant preparation of TEAD transcription factor.
Lišková, Růžena ; Novák, Petr (advisor) ; Staněk, Ondřej (referee)
Recombinant preparation of TEAD transcription factor (abstract) The TEAD family transcription factors play an important role during devolopment of organisms, where their main purpose is to regulate organ size by activating expression of proteins involved in cell growth and differentiation and apoptosis inhibition. TEAD proteins activity is regulated by signalling pathways and interactions with coactivators. Disregulation of these mechanisms can lead to development of tumors, which is the reason why TEAD proteins became an interesting target for development of new anticancer drugs based on inhibiting their activity. There are several possibilities how to inhibit activity of a transcription factor including blocking its bond to DNA. To design a new drug that blocks transcription factors binding to DNA the structural basis of interaction of these two molecules has to be known first. In this thesis the DNA binding domain of human protein TEAD1 was prepared using the technique of recombinant expression in bacteria E. coli. Suitable conditions of protein production were found and the DNA binding domain of TEAD1 protein was purified so it will be possible to use it for structural analysis of its intraction with DNA.
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Preparation of tumour ligand B7-H6 with coiled-coil tag and verifying of its binding to receptor NKp30
Krejčová, Kateřina ; Vaněk, Ondřej (advisor) ; Moserová, Michaela (referee)
Natural killer cells (NK cells) are part of innate antitumor immunity. These cells have the capacity to prevent viral infection or malignant transformation without prior antigen sensitization. Activation of NK cells consist of different recognition strategies. Mechanism of activation is based on down-regulated expression of MHC gp I molecules on the cell surface. NK cells possess both activation and inhibitory receptors that transmit activation or inhibitory signals which determine if NK cells are activated or not, and thus whether the target cell will be lysed or spared. NKp30 is a type I transmembrane receptor which recognize the stress-induced cell surface ligand B7-H6. Interaction of these two proteins leads to the initiation of immune response. The main aim of this thesis is the preparation of cell ligand B7-H6 with coiled-coil peptide tag in human embryonic kidney cell lines HEK293 GnTI- and HEK293T. Successful preparation of B7-H6 with coiled-coil tag on its C-terminus was verified by mass spectrometry. Its interaction with natural cytotoxicity receptor NKp30 was also proven by sedimentation analysis. Key words: NK cells, recombinant expression, B7-H6, HEK293, coiled-coil (This thesis is written in Czech)
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Preparation of transcription factor FOXK2 - DNA binding domain
Kobrle, Lukáš ; Kukačka, Zdeněk (advisor) ; Bělonožníková, Kateřina (referee)
Transcription factors are specific proteins, which are able to regulate transcription and which are divided into individual families based on structural motifs. One of these families is the FOX family, which also includes the transcription factor FOXK2, which was the studying subject of this work. The FOXK2 protein regulates many cellular processes, including cell proliferation and metabolism and plays an important role in carcinogenesis, as its high expression has been reported in cases of lung, liver and kidney cancer. In this work, the DNA binding domain of the transcription factor FOXK2 was prepared by recombinant expression of Escherichia coli cells. The obtained protein was afterwards purified and its interaction with DNA was studied by native mass spectrometry.
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Structure and function of C-type lectin NK cell receptors studied by recombinant expression and protein crystallography
Vaněk, Ondřej
Department of Biochemistry, Faculty of Science, Charles University in Prague 2010 Structure and function of C-type lectin NK cell receptors studied by recombinant expression and protein crystallography Abstract of Ph.D. thesis Ondřej Vaněk Supervisor: Prof. RNDr. Karel Bezouška, DSc. Natural killer cells (NK cells) were found out for their ability to spontaneously kill certain allogeneic tumour cell lines, without any previous sensitization. NK cells are part of non- adaptive immune response with very short reaction time against pathogens such as viruses, intracellular bacteria, parasites, and they are responsible for elimination of certain tumour cells and thus they are able to fight against malignancy and formation of metastasis. Activity of NK cells is regulated by the balance between activation and inhibitory signals mediated by the NK cell surface receptors. From the structural point of view, the majority of NK cell surface receptors could be classified as the C-type lectin or immunoglobulin-like receptors. One of many C-type lectin subgroups are type II lymphocyte receptors that are expressed on the NK cell surface. This study had two main aims. The first one was to find suitable expression and purification systems for selected C-type lectin receptors of NK cells and the other one was to perform their...
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Recombinant preparation of DNA binding domain of transcription factor TEAD4
Zákopčaník, Marek ; Novák, Petr (advisor) ; Šulc, Miroslav (referee)
6 Abstract Transcription factors play a key role in the management of cell growth and differ- entiation and their deregulation is associated with many cancers. TEAD proteins utilise highly conserved DNA binding domain to recognise specific DNA sequences. This domain could facilitate new drug design and development. The goal of this master thesis includes recombinant preparation of DNA binding domain of transcriptional factor TEAD4 extended by a part of an unstruc- tured variable sequence, which connects this domain with transactivation domain. Purification steps include affinity chromatography followed by size exclusion chro- matography. The characterization of produced protein was performed by mass spectrometry and finally, native gel electrophoresis was used to prove the ability of the produced protein to bind DNA. During purification steps, a fragmentation from C-terminus was observed. Based on analysis of the mass spectra, three most represented forms of produced protein were described all of which were fragmented. The most abundant form (55%) consisted of amino acids 30-131 from TEAD4 protein. Second most abun- dant form (18%) consisted of amino acids 30-144 and the third form consisted of amino acids 30-81. Native gel electrophoresis verified the ability to bind DNA, the efficiency was however lower...
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Engineering of microbial glycosidases for modifying synthetic potential
Hovorková, Michaela ; Bojarová, Pavla (advisor) ; Lichá, Irena (referee)
Glycosidases (EC 3.2.1.) alias glycoside hydrolases are enzymes that catalyze the cleavage of a glycosidic bond between two carbohydrates or between a carbohydrate and an aglycone. Under suitable conditions (especially reduction of water activity in the reaction mixture), these enzymes are also able to synthesize a glycosidic bond. By targeted mutagenesis of the catalytic centre of the enzymes, it is possible to suppress or completely abolish their hydrolytic activity. Enzyme synthesis using glycosidases makes it possible to prepare bioactive galactosides, for example galectin ligands. The present work deals mainly with β-galactosidase from Bacillus circulans, its recombinant expression and mutagenesis. In the first part of the work, the commercially prepared plasmid of -galactosidase from B. circulans isoform A that I designed was used for recombinant expression in E. coli. It was necessary to optimize the conditions of the enzyme production. As it is a large protein (189 kDa), the expression vector pCOLD II and cold production at 15 ř C were used. The enzyme is specific for the formation of the β-1,4 glycosidic bond and has been used to synthesize complex tri- and tetrasaccharide ligands that cannot be prepared with a crude commercial preparation containing undesirable enzyme activities....
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Recombinant expression of transcription factor TEAD1.
Řeháková, Jana ; Novák, Petr (advisor) ; Bláha, Jan (referee)
TEAD1 is one of the members of the TEAD transcription factor family. This transcription factor is very important, for example for development of organs. The structure of the entire TEAD1 transcription factor is not now yet known. Nevertheless, structure of two important domains are known. The TEA binding domain, which is important for the binding of the transcription factor TEAD1 to DNA, and the transactivation domain, to which coactivators bind. TEAD1 binds to DNA and upon coactivator bind it affects the transcription of various genes. Genes, that are affected by the transcription factor TEAD1 includes genes regulating proliferation, differentiation and apoptosis of cells. TEAD1 is also the target of the Hippo signalling pathway, which is active in adulthood and prevents abnormal growth of organs. Important for the activity of transcriptional factor TEAD1 are post-translation modifications, such as palmitoylation and phosphorylation. To discover the entire structure of the transcriptional factor TEAD1 and the way it interacts with DNA, the transcriptional factor TEAD1 was prepared recombinationally by expression in cells of Escherichia coli bacteria. Suitable conditions for production of the transcriptional factor TEAD1 were found and the cleavage of the histidine tag by thrombin was performed....
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