|
|
Deciphering the biological role of Ddi1-like protein family
Sivá, Monika ; Grantz Šašková, Klára (advisor) ; Bařinka, Cyril (referee) ; Stopka, Pavel (referee)
Ddi1-like protein family has been recently raised into the spotlight by the scientific community due to its important roles in cellular homeostasis maintenance. It represents a specific group among shuttling proteins of the ubiquitin-proteasome system. When compared to other shuttles, Ddi1-like protein family members harbor a unique retroviral-protease like domain besides the conventional ubiquitin-like (UBL) domain and domains interacting with ubiquitin. In addition, a helical domain of Ddi (HDD) has been recently found in most of the orthologs. In this thesis, I focus on characterization of several members of Ddi1-like protein family, both on molecular level using NMR and in model mouse strains via a variety of biological methods. Solution structure of the UBL domain of Ddi1p of S. cerevisiae was solved and its characteristics were compared to those of the UBL domain of its human ortholog. Furthermore, we show that human DDI2 specifically binds to ubiquitin with its terminal domains, both the UBL and the UIM; however, with very low affinity in contrast to binding properties of its yeast counterpart. Our study also show that hDDI2 does not form a head-to-tail homodimer. Based on our structural studies, we hypothesize that human DDI2 might have evolved a different function compared to its yeast...
|
|
|
Generation and Characterization of Glutamate Carboxypeptidase II (GCPII)-Deficient Mice
Vorlová, Barbora ; Šácha, Pavel (advisor) ; Eckschlager, Tomáš (referee) ; Bařinka, Cyril (referee)
Glutamate carboxypeptidase II (GCPII) is a transmembrane glycoprotein, which consists of short intracellular and transmembrane domains, and a large extracellular domain possessing carboxypeptidase activity. In the human body, GCPII fulfils a neuromodulatory function in the brain and facilitates folate absorption in the small intestine. In addition to the brain and small intestine, high level of GCPII is also present in the prostate and kidney. However, GCPII function in these tissues has not been determined yet. To study the role of GCPII in detail, several research groups attempted to inactivate GCPII encoding gene Folh1 in mice. Surprisingly, the experiments led to rather conflicting results ranging from embryonic lethality to generation of viable GCPII-deficient mice without any obvious phenotype. This dissertation project aimed to dissect the discrepancy using alternative strategy for gene modification. For this purpose, we designed TALENs that specifically targeted exon 11 of Folh1 gene and manipulated mouse zygotes of C57BL/6NCrl genetic background. We analysed all genetically modified mice of F0 generation for presence of TALEN-mediated mutations and established 5 different GCPII-mutant mouse colonies from founder mice that altogether carried 2 frame-shift mutations and 3 small in-frame...
|
|
|
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...
|
|
|
Glutamate Carboxypeptidase II - Structural and Biochemical Characterization and Structure-Assisted Drug Design
Ptáček, Jakub ; Bařinka, Cyril (advisor) ; Obšil, Tomáš (referee) ; Brynda, Jiří (referee)
Glutamate carboxypeptidase II (GCPII) is a human membrane-bound metallopeptidase discovered more than 30 years ago. It has attracted attention of biomedical scientists thanks to its diverse tissue expression profile and different biological functions. GCPII is detected on the surface of astrocytes in both central and peripheral nervous systems where it is responsible for the cleavage of N-acetyl-L-aspartyl-L-glutamate (NAAG), the most abundant mammalian peptidic neurotransmitter. Glutamate, one of the hydrolytic products, is a potent excitatory neurotransmitter and its overproduction has been shown to be responsible for cell death in various neurological disorders by a so-called glutamate excitotoxicity mechanism. Together with the fact that NAAG acts neuroprotectively it has been postulated (and later confirmed) that GCPII inhibition has a therapeutic potential in such disorders. Prostate cancer (PCa) is the second most prevalent cancer in men and despite its slow progression it is prone to metastasize thus posing a life threat. GCPII has been found to be overexpressed in prostate tumor cells compared to the healthy tissue (therefore it is also termed prostate-specific membrane antigen - PSMA) thus representing an excellent biomarker of PCa validated by many publications and clinical studies....
|
|
|
Regulation of the activity of aspartic and serine proteases by selective natural inhibitors
Srp, Jaroslav ; Mareš, Michael (advisor) ; Novák, Petr (referee) ; Bařinka, Cyril (referee)
Proteases are involved in many physiological processes and their dysregulation is associated with various pathologies. Protease activity is effectively controlled by natural inhibitors. This PhD thesis is focused on the inhibitors of aspartic and serine proteases of animal and plant origin and provides the identification, biochemical characterization and structural description of their inhibition mechanisms. Plant Kunitz inhibitors are produced as defensive proteins, and they are able to block activities of a broad spectrum of proteases. In this thesis, the digestive proteolytic system of the Colorado potato beetle, a herbivore pest of potato plants, was described with the help of functional proteomics. It was shown that aspartic and serine proteases from this herbivore are effectively blocked by two potato Kunitz inhibitors (namely PCDI, PSPI). Using structural analysis, novel types of reactive centers were identified on PCDI and PSPI molecules for the inhibition of aspartic protease cathepsin D and the serine proteases trypsin and chymotrypsin. The analysis of the reactive center on a PCDI with the crystal structure of digestive cathepsin D from the Colorado potato beetle explained the mechanism of their interaction. Sphingolipids were identified as the first endogenous inhibitors of human...
|
|
|
Tubulin post-translational modifications
Kropáčková, Veronika ; Bařinka, Cyril (advisor) ; Dostál, Vojtěch (referee)
Microtubules composed of αβ-tubulin heterodimers are an integral part of the cellular cytoskeleton of eukaryotic organisms. They participate in the cellular transport, determine the distribution of membrane organelles and help defining cellular polarity. Microtubules are part of dynamic structures such as mitotic spindle, but they also form stable structures such as flagellar and ciliar axonemes. Microtubules have many distinct functions in cells and tissues and therefore must differ from each other in some way. Post-translational modificationsof αβ-tubulin in microtubules are the major source of their diversity and collectively define so-called tubulin code. Twelve posttranslational modifications of tubulin/microtubules have been identified so far. Unraveling the mechanisms involved in post-translational modifications of tubulin/microtubules, including the identification of responsible enzymes, is an important source of understanding of the effects of these modifications on biological functions. Key words: tubulin, post-translational modificaton, microtubules, acetylation, tyrosination, polyamination, polyglutamylation
|
|
|
Antibody derivatives for the detection of human glutamatecarboxypeptidase II
Bělousová, Nikola ; Bařinka, Cyril (advisor) ; Pavlíček, Jiří (referee)
Prostate cancer is one of the most common human malignancies and, consequently it is critical to develop appropriate diagnostic and therapeutic tools. Glutamate carboxypeptidase II (GCPII) is currently being considered one of the most important prostate cancer markers due to its tissue- specific expression. Whereas in healthy prostatic tissue the expression levels of GCPII are low, the transformation into the tumor is associated with the substantial increase of GCPII expression, with the highest levels observed in androgen-independent metastatic tumors. GCPII is thus considered a promising marker for early phase as well as advanced metastatic stages of prostate cancer. Current research is focused on the development of highly sensitive and specific reagents that allow detection of small amounts of GCPII, for example in early stages of cancer. Antibody derivatives are promising molecules for this purpose because they have high affinity and specificity and minimum negative side effects. Protein engineering is a prefered approach for preparation of various antibody molecules that differ in size, binding properties, stability, solubility, and production means. Different types of derivatives are being developed for medical needs such as in vitro diagnosis, therapy, and in vivo imagingSmall molecular...
|
|
|
Structural studies of inhibitory mechanisms of phosphatidylinositol kinases
Gregor, Jiří ; Bouřa, Evžen (advisor) ; Bařinka, Cyril (referee)
+ssRNA viruses after entering the cell develop platforms for RNA replication called replication organelles. Due to the activity of phosphatidylinositol 4-kinases is in these areas a higher concentration of PI4P, which establishes suitable binding environment for the viral polymerase 3DPOL . One of these kinases is PI4KB, which is recruited to the membrane by the ACBD3 protein, which is itself recruited by giantin. Some kobuviruses and enteroviruses from the Picornaviridae family use their 3A protein to displace ACBD3 protein from the complex with giantin and transfer it from Golgi aparathus to the replication organelles. Here, PI4KB binds to ACBD3 protein and synthesizes PI4P. Recently, two proteins - TBC1D22A and TBC1D22B - were discovered to bind to the same area of ACBD3 protein as PI4KB. The goal of this project was verification of this interaction and its subsequent characterization (e.g. dissociation constant measurements). My goal was to crystallize complexes of these interaction partners and to solve three-dimensional structure. Our results suggest, that interaction of ACBD3 protein with peptides derived from TBC1D22A and TBC1D22B proteins is much lower compared to interaction between ACBD3 protein and PI4KB. I successfully prepared crystals, however, they diffracted poorly, not allowing us to solve...
|
|
|
Zinc-Dependent Hydrolases: Structure-Function Study of Glutamate Carboxypeptidase II and Histone Deacetylase 6
Škultétyová, Ľubica ; Bařinka, Cyril (advisor) ; Obšil, Tomáš (referee) ; Novák, Petr (referee)
Zinc-binding proteins represent approximately one tenth of the proteome and a good portion of them are zinc-dependent hydrolases. This thesis focuses on biochemical and structural characterization of glutamate carboxypeptidase II (GCPII) and histone deacetylase 6 (HDAC6), two members of the zinc-dependent metallohydrolase superfamily. We describe here their interactions with natural substrates and inhibitors. GCPII is a homodimeric membrane protease catalyzing hydrolytic cleavage of glutamate from the neurotransmitter N-acetylaspartylglutamate (NAAG) and dietary folates in the central and peripheral nervous systems and small intestine, respectively. This enzyme is associated with several neurological disorders and also presents an ideal target for imaging and treatment of prostate cancer. GCPII inhibitors typically consist of a zinc-binding group (ZBG) linked to an S1' docking moiety (a glutamate moiety or its isostere). As such, these compounds are highly hydrophilic molecules therefore unable to cross the blood-brain barrier and this hampers targeting GCPII to the central nervous system. Different approaches are adopted to alter the S1' docking moiety of the existing inhibitors. As a part of this thesis, we present different strategies relying on replacement of the canonical P1' glutamate residue...
|
|
|
The effect of palmitoylation on biological functions of proteins
Frýdová, Tereza ; Bařinka, Cyril (advisor) ; Pavlíček, Jiří (referee)
Palmitoylation is lipid post-translational modification of proteins. It is one of the most common protein lipidations in eukaryotic cells. Unlike other lipid post-translational modifications, palmitoylation is reversible. Its unique reversibility determines important characteristic of palmitoylation - palmitoylation can be regulated in the similiar way as ubiquitination or phosphorylation. At the same time, palmitoylation regulates interactions between cytosolic and membrane domains. Palmitoylation also plays an important role in the intracellular trafficking. It also affects protein stability and protein-protein interactions. Aberrant palmitoylation is linked to several neurodegenerative diseases, such as Alzheimer's disease or neuronal ceroid lipofuscinosis. Key words: palmitoylation, depalmitoylation, post-translational modification, DHHC protein domain, lipid modification
|
guest ::
