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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Elucidation of the properties and structure of the pore-forming domain of colicin U produced by bacterium Shigella boydii.
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Krůšek, Jan (referee) ; Osička, Radim (referee)
Colicin U is a protein produced by bacterium Shigella boydii. It belongs to the group of pore-forming colicins. These colicins interact with receptors in the outer membrane of bacteria closely related to a producing colicinogenic strain. After interaction with the receptor, colicin is translocated across the outer membrane and periplasm to the cytoplasmic membrane where it forms pores. Consequently, the pore formation leads to membrane depolarization and cell death. In this thesis I decided to study the pore-forming properties of colicin U and its membrane topology. It is shown that colicin U pores are formed by only one colicin molecule and they are voltage dependent. Using measurements with nonelectrolytes we estimated a theoretical inner profile of the pore and its inner diameter to be between 0.7 and 1 nm. Above that, a membrane topology of colicin U pore-forming domain (PFD) is studied. BLM measurements with biotinylated colicin U showed that a significant part of colicin's PFD was translocated to the opposite side of the membrane after the pore opening. The segment between substituted amino acids F463 and D486 was evidenced to be on the trans side of the membrane after the pore opening. Additionally, properties of peptide H1, which reflects a significant part of the first α- helix of colicin...
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Current methods in protein-protein interactions research
Křivková, Jana ; Hrdý, Ivan (advisor) ; Kučerová, Jitka (referee)
Protein-protein interactions (PPI) have a crucial role in all processes in living cells. Understanding the interactions between proteins allows us to describe cell processes in more detail and their study opens new possibilities for drug design. The importance of the question of studying PPI is shown in the recent development of various methods for their identification and description. The aim of this thesis is to give an overview of new and improved experimental methods of identification and characterization of protein-protein interactions. Methods described in this thesis are divided in four chapters - proximity-dependent labelling methods (BioID, BioID2, APEX, TurboID, MiniTurbo, PUP-IT, AirID, SPPLAT, EMARS), cross-linking methods (XS-MS), fluorescence methods for identification and visualization (BiFC, FRET, BRET) and biophysical methods for description of kinetics and thermodynamics parameters of interaction (SPR, ITC, MT).
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Advanced methods of assaying lectin-carbohydrate interaction
Červený, Jakub ; Bosáková, Zuzana (advisor) ; Pavlíček, Jiří (referee)
A reliable and reproducible quantification and detailed characterization of the interactions between a biomedically relevant protein and its synthetic carbohydrate ligand can provide new information for the design of better diagnostic and therapeutic tools. A high sensitivity and specificity are essential requirements for the feasibility of an analytical method. These parameters can be difficult to achieve for highly complex systems such as lectin-saccharide complexes. On the other hand, carbohydrate-based diagnostics and therapeutics offer the great advantage of detecting biologically active lectin receptors, which cannot be achieved with antibodies. In this work we demonstrate the use of the BLI technique to monitor lectin- carbohydrate interactions for a multivalent system. Using functionalization of a novel construct of galectin-1 with an in vivo biotinylated AVI tag, suitable immobilization on a biosensor was achieved without the loss of its lectin activity. Due to the high sensitivity of this technique, kinetic parameters of interaction with prepared multivalent neoglycoproteins based on LacNAc epitopes were obtained in the micro- to nanolar KD range. The complementarity of this method was demonstrated by parallel ITC and competitive ELISA measurements. The neoglycoprotein with a lower LacNAc...
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Investigation of newly discovered protein GL50803_16424 in Giardia intestinalis.
Pelc, Josef ; Doležal, Pavel (advisor) ; Pyrih, Jan (referee)
The anaerobic unicellular eukaryotic organism Giardia intestinalis is a worldwide parasite. Giardiasis, the intestinal disease caused by Giardia, is one of the most common parasitic disease in the developed part of the world, that causes health problems not only to humans but also to animals. This organism is also interesting for its many unique cellular features. One of them is the presence of mitosomes - the organelles derived from mitochondria. Analogously to mitochondria, mitosome is limited by two membranes and shares the mode of the protein transport. However, mitosome does not have its own genome and as far as we know, there is only one pathway of the iron-sulfur cluster biosynthesis in this organelle. Using the in vivo enzymatic tagging technique, several novel mitosomal proteins were identified, including GL50803_16424. The protein GL50803_16424 attracted our attention by interacting with components of all mitosomal subcompartments: the outer membrane, the membrane and the matrix. In addition, the expression of HA-tagged GL50803_16424 resulted in the formation of peculiar structures near the mitosomes never seen before in G. intestinalis. Bioinformatic approaches revealed that the GL50803_16424 has domain similar to the myelodysplasia- myeloid leukemia factor 1-interacting protein. Our...
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Candida parapsilosis secreted aspartic proteinases: processing and secretion
Vinterová, Zuzana ; Heidingsfeld, Olga (advisor) ; Hodek, Petr (referee) ; Szotáková, Barbora (referee)
Candida parapsilosis is an emerging human opportunistic pathogen causing a wide spectrum of potentially life-threatening infections in immunocompromised hosts. One of the most important virulence factors of Candida spp. is a production of secreted aspartic proteinases (Saps). Presented thesis is mainly focused on the study of secreted aspartic proteinase 1 (Sapp1p) of C. parapsilosis, its processing and secretion under variable conditions and by use of various experimental models. Sapp1p is secreted by C. parapsilosis cells into the extracellular space as a completely processed and fully active enzyme. Experiments studying the C. parapsilosis cell wall (CW) confirmed the prolonged presence of completely processed Sapp1p on the cell surface (CW- Sapp1p). Proteolytic activity assay performed with the intact cells showed that CW-Sapp1p is proteolytically active prior to its release into the extracellular space and is capable of substrate cleavage. Biotinylation experiments with consecutive MS analysis revealed that CW-Sapp1p biotinylation is incomplete but saturable process, leaving partially unlabelled molecules. The accessibility of individual lysine residues in the Sapp1p molecule varied, with exception of four residues that were labelled in all of our experiments performed. The final step of...
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