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Role of yeast WSS1 protease in DNA repair.
Adámek, Michael ; Grantz Šašková, Klára (advisor) ; Čáp, Michal (referee)
Sustaining the integrity of DNA throughout the lifetime is critical for every living organism. Therefore organisms evolved numerous ways to detect and repair different types of DNA damage caused by various endogenous and exogenous factors resulting in replication stress. Defects in these repair mechanisms can lead to severe human diseases such as neurological disorders, familial cancers or developmental syndromes. In presented master thesis, we investigated the function of a yeast protein named Wss1, a metalloprotease that participates in a recently discovered DNA repair pathway that proteolytically removes DNA-protein crosslinks. Wss1 shows strong negative interaction with another DNA repair protease, Ddi1, in which case was discovered, that double-deleted yeast strain lacking WSS1 and DDI1 is hypersensitive to hydroxyurea. Hydroxurea is a ribonucleotide reductase inhibitor that, in the end, arrests cells in the S-phase of cell-cycle. Based on previous studies, we performed rescue experiments with various deletions and single-site mutants of Wss1p to assess the involvement of particular yeast Wss1p domains in the replication stress response to hudroxyurea.
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Analysis of secretome from Trichobilharzia regenti cercariae and characterisation of selected peptidases
Konečný, Lukáš ; Kašný, Martin (advisor) ; Horn, Martin (referee)
(English): Trichobilharzia regenti is a neurotropic parasite of birds from the family Schistosomatidae. Cercariae, the invasive stages of these trematodes actively penetrate the host skin employing excretory- secretory products (ESPs), which contain proteolytic enzymes able to disrupt host tissues and thus reach the successful transmission. The most abundant secreted enzyme responsible for cercarial penetration of the human schistosome S. mansoni is a cercarial elastase. This serine peptidase is well known for the degradation of skin proteins such as elastin, keratin, collagen or laminin. However, the active expression of the orthologue of this enzyme has never been found in the genus Trichobilharzia. For this reason, it was firmly believed, that cercaria of T. regenti uses mainly cysteine peptidases for the invasion of the host, particularly cathepsins, which were repeatedly identified in this life stage. To strengthen this hypothesis, we incubated T. regenti cercariae in the apparatus with the excised duck skin stimulating the release of their glands' content. The collected ESPs were further analysed by shotgun mass-spectrometry and for the first time, the protein form of cercarial elastase was identified. Unfortunately, we failed to produce its active recombinant protein in yeast and bacterial...
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Proteolytic systems of the blood fluke (Schistosoma mansoni).
Fajtová, Pavla ; Horn, Martin (advisor) ; Bařinka, Cyril (referee) ; Sojka, Daniel (referee)
Schistosomiasis is a serious parasitic disease caused by blood flukes of the genus Schistosoma. It is a global health problem with more than 200 million people infected and 750 million people at risk. Current therapy relies on a single drug, praziquantel, for which there are concerns of emerging drug resistance. Proteases of schistosoma are promising target molecules for the development of new therapeutic strategies against schistosomiasis. This work focuses on the comprehensive characterization of proteolytic systems of Schistosoma mansoni and determination of their role in the interaction with the human host. First, the major proteolytic activities secreted by individual developmental stages of schistosoma that parasitize the human body were classified using functional proteomics. This analysis demonstrated their complex and specific distribution with predominant serine and cysteine proteases and metalloproteases. Second, tegumental and digestive proteases, namely prolyl oligopeptidase and cathepsins B, C and D, were identified by chemical genomics as suitable target molecules for therapeutic intervention. Prolyl oligopeptidase was biochemically characterized using a recombinant protein, its effective inhibitors were developed as templates for antischistosomal drugs, and a biological role of the...
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Non-structural proteins of Zika and Dengue virus with enzyme activity
Krýsová, Eliška ; Konvalinka, Jan (advisor) ; Novotný, Marian (referee)
Zika and Dengue viruses codes their own enzymes which helps them in different stages of the replication cycle. NS3 a NS5 proteins and their cofactors play an essential role in flaviviral life cycle. Although their structure was already solved, many aspects of their function remain unclear. The main subject of this bachelor thesis is the role of these proteins in flaviviral life cycle, polyprotein cleavage, replication and protein-protein interaction. These enzymes keep many particular enzymatic activities such as protease, helicase, methyltrasferase and polymerase. They are both structurally and functionally separated, which is interesting regarding autoactivation and protein-protein interaction. Since Zika and Dengue infections remain a serious health care issue, it is necessary to understand the molecular mechanisms behind their replication. Keywords: protease, polymerase, Zika, Dengue, polyprotein processing, antiviral therapy
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Ddi1-like proteins: a novel family of retroviral-like aspartyl proteases
Šmilauerová, Kristýna ; Grantz Šašková, Klára (advisor) ; Šmahel, Michal (referee)
Ubiquitin-proteasome system is one of the key pathways which maintain cell homeostasis. Its purpose is to degrade damaged, misfolded or unnecessary proteins. It is also involved in multiple other processes such as DNA damage repair, cell cycle control or signaling. The entire system consists of multiple components, which are mutually strictly regulated. Important part of this system is group of so called proteasome adaptor proteins. Their role is to recognize and bind targeted substrates and transport them to the proteasome for degradation. Ddi1-like (abbrev. from DNA damage-inducible protein 1) protein family, a group of proteins with retroviral aspartyl protease-like domain, belongs to proteasome adaptor proteins. Global biological role of this protein family is only partially understood the most studied member is Ddi1 protein from Saccharomyces cerevisiae, and it is thus a subject of active research. This thesis summarizes published information about this protein family, describes its general characteristics and known functions, situates them in the context of cell processes and thereby might suggest the course of further study.
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Parasitic protease SmCB2 as a target for the treatment of schistosomiasis
Bakardjieva, Marina ; Mareš, Michael (advisor) ; Mikeš, Libor (referee)
Blood flukes of the genus Schistosoma are parasitic trematodes that cause schistosomiasis, a serious disease afflicting more than 240 million people. The proteolytic system of schistosomes is essential for their viability: it participates in important processes during host-parasite interactions such as food digestion, invasion and tissue migration. Thus, schistosomal proteases are promising molecular targets for therapeutic intervention in schistosomiasis treatment. The thesis focuses on the protease cathepsin B2 from S. mansoni (SmCB2) which has not been studied in detail so far in terms of biochemical properties and biological function. Recombinant SmCB2 was prepared using yeast and bacterial expression systems and was chromatographically purified. Using an in vitro activity assay, the first effective inhibitors of SmCB2 were identified which inhibited its proteolytic activity in submicromolar concentrations. Specific polyclonal antibodies against SmCB2 were prepared and used for immunomicroscopic localization of this protease on the surface of the parasite. ELISA analysis demonstrated that SmCB2 is a parasite antigen recognized by the host immune system in the mouse model of schistosomiasis. The thesis provides valuable information about SmCB2 as a potential target molecule for synthetic...
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Cathepsins L of Diplostomum pseudospathaceum cercariae
Perháčová, Terézia ; Mikeš, Libor (advisor) ; Hartmann, David (referee)
This study is focused on cercarial cysteine peptidases of the trematode Diplostomum pseudospathaceum. It follows previous research which confirmed the presence of a 24kDa cysteine peptidase in cercariae biochemically and by mass spectrometry. It was postulated, that the function of this peptidase is histolytic, when cercariae penetrate the tissues. During an attempt to purify this peptidase and characterize its peptidolytic activity, it was found out that the cercarial homogenate containsmore different peptidases varying in their pI. Tests of peptidolytic activity and inhibition have shown that these peptidases are cathepsin L-like. They are active over a broad spectrum of pH with optima of activities in weakly acidicor neutral pH. Using degenerate primers based on conserved motifs of cysteine pepridases, partial sequences of three genes for cathepsin L of D. pseudospataceum (DpCL1, 2 a 3) were obtained. Then the complete sequences of DpCL2 and 3 genes and partial sequence (without 5'end) of DpCL1 were obtained by RACE PCR. To confirm function of these peptidases we tried to immunolocalize them. We assumed that they are localized in penetration glands. Preliminary results suggested that some of the cathepsins could be also localized in the gut of cercariae. For more detailed biochemical...
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Proteolytic system of blood flukes of the genus Schistosoma
Bakardjieva, Marina ; Mareš, Michael (advisor) ; Dvořák, Jan (referee)
Blood flukes of the genus Schistosoma are parasitic trematodes causing a disease called schistosomiasis, which afflicts more than 200 million people in the tropics and subtropics. Adult schistosomes live in human blood vessels and feed on blood. Critical nutrients required for growth, development and reproduction of schistosomes are obtained from the major blood protein haemoglobin. Its digestion is mediated by the proteolytic arsenal of the schistosome digestive tract, which includes enzymes with complementary specificity belonging to the classes of cysteine and aspartic proteases, and metalloproteases. Proteolytic enzymes also play an important role in other processes, such as host penetration, tissue migration, immune evasion and modulation of inflammation. Here, serine and cysteine proteases importantly participate. The proteolytic system is essential for the viability of schistosomes and is a current topic of intense research focused on the development of new vaccines and chemotherapeutics for the treatment of schistosomiasis. Powered by TCPDF (www.tcpdf.org)
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Structural and functional analysis of cathepsin B1 from the blood fluke, Schistosoma mansoni
Jílková, Adéla ; Mareš, Michael (advisor) ; Obšil, Tomáš (referee) ; Mikeš, Libor (referee)
Schistosomiasis is a serious infectious disease that afflicts over 200 million people in tropical and subtropical regions. It is caused by Schistosoma blood flukes that live in human blood vessels and obtain nutrients from host hemoglobin, which is degraded by digestive proteases. Current therapy relies on a single drug and concern over resistance necessitates new drug development. In Schistosoma mansoni, cathepsin B1 (SmCB1) is a critical digestive protease that is a target molecule for therapeutic interventions. This thesis provides a comprehensive characterization of SmCB1 focused on structure-activity relationships and inhibitory regulation based on six crystal structures solved for SmCB1 molecular forms and complexes. SmCB1 is biosynthesized as an inactive zymogen in which the N-terminal propeptide operates as a natural intra-molecular inhibitor by blocking the active site. Detailed biochemical and structural analyses have identified a new and, so far, unique mechanism of SmCB1 zymogen activation through which the propeptide is proteolytically removed and the regulatory role of glycosaminoglycans in this process has been described. A study of SmCB1 proteolytic activity has revealed that the enzyme acts in two modes, as endopeptidase and exopeptidase, which makes it an efficient tool for host...
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Serine protease SmSP2 of Schistosoma mansoni
Leontovyč, Adrian ; Konvalinka, Jan (advisor) ; Vaněk, Ondřej (referee)
Blood fluke Schistosoma mansoni is one of the most important human parasites. Proteolytic system of schistosoma is crucial for parasite - host interactions. Therefore some of the proteases became potential therapeutic targets. This work is focused on not yet characterized serine protease SmSP2. SmSP2 is newly discovered protease of S. mansoni, whose biological role is unknown. This protease is highly expressed in developmental stages parasitizing humans. SmSP2 was recombinantly expressed in prokaryotic and eukaryotic expression system (E. coli a P. pastoris) and purified using chromatographic methods. Recombinant SmSP2 was used for polyclonal antibody production. Conditions for refolding were optimized. Basic biochemical properties of the protease were detected and substrate amino acid preferences for P1 - P4 sites for single aminoacids were identified using synthetic fluorogenic peptides for positional scanning substrate combinatorial library (PS-SCL). (In Czech)
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