Protein phosphorylation by protein kinases is a key mechanizm that enables both eukaryotic and prokaryotic organizm sense and read environmental signals and convert these signals into changes in gene expression and thus proper biological response. One of the main phosphorylation systems in bacteria consists of eukaryotic-like Ser/ Thr protein kinases. The genome of human pathogen Streptococcus pneumoniae contains single Ser/ Thr protein kinase StkP. StkP regulates virulence, competence, stress resistance, gene expression and plays an important role in the regulation of cell division cycle. Analysis of phosphoproteome maps of both wild type and ΔstkP mutant strain of S. pneumoniae showed that in vivo StkP phosphorylates several putative substrates including the cell division protein DivIVA (NOVÁKOVÁ et al., 2010). DivIVA in S. pneumoniae is localized at midcell and at the cell poles. It was proposed to be primarily involved in the formation and maturation of the cell poles (FADDA et al., 2007). The aim of this thesis was to investigate phosphorylation of the cell division protein DivIVA in S. pneumoniae. Gene divIVA was cloned, expressed in E. coli and protein was purified via affinity chromatography. Phosphorylation of DivIVA by StkP was examined in a kinase assay. We confirmed that DivIVA is a direct...

Phosphorylation is an important mechanism for regulation of protein function and aktivity. Tyrosine phosphorylation plays a critical role in signaling pathways. Aberrant tyrosine phosphorylation was observed in many cancer types. My work follows patological details of tyrosine phosphorylation sites of lung and colorectal cancers. Point of view includes aminoacid sequence, secondary structure, domain localization, expression, model organism ortholog occurrence. The project is based on analysis of literary informations and data from protein databases. There are no new phosphorylation sites in observed cancer types. Regular secondary structures, α-helices and β-sheets, are significantly phosphorylated in compare with loops. Annexin and Kinase domains are the most phosphorylated. Gene expression change of phosphorylated proteins occurs in observed cancer cells. Powered by TCPDF (www.tcpdf.org)

Protein phosphorylation is a common post-translational protein modification used in almost all cellular processes. When a phosphate group is added to an amino acid side chain, it may alter the protein conformation and protein-protein interactions due to its size and its negative charge. It may also change the protein function, activity and even localization within the cell. Experimental detection of phosphorylation is still extremely labor demanding and very expensive, even when deploying protein mass spectrometry. For this very reason many bioinformatics scientific groups focus on the prediction of protein phosphorylation sites. Recent analyses of phosphorylation sites studied mainly non-phosphorylated phosphorylation sites and the distribution and representation of amino acids sequentially neighboring them. Since sequentially more distant, but structurally close amino acids can contribute to the recognition of protein substrate by protein kinase, structural environment of phosphorylation sites was studied in this thesis. Furthermore, 3D structures of phosphorylation sites were comprehensively studied for the first time in a phosphorylated state and the results were compared with the results obtained from the analysis of non- phosphorylated sites. Phosphorylation sites were found mostly within...

Mood disorders are serious diseases. Nevertheless, their pathophysiology is not sufficiently clarified. Biological markers that would facilitate the diagnosis or successful prediction of pharmacotherapy are still being sought. The aim of the study was to find out whether mitochondrial functions are affected by antidepressants, mood stabilizers and depression. Our research is based on recent hypotheses of mood disorders, the advanced monoamine hypothesis, the neurotrophic hypothesis, and the mitochondrial dysfunction hypothesis. We assume that impaired function of mitochondria leads to neuronal damage and can be related to the origin of mood disorders. Effects of antidepressants and mood stabilizers on mitochondrial functions can be related to their therapeutic or side effects. In vitro effects of pharmacologically different antidepressants and mood stabilizers on the activities of mitochondrial enzymes were measured in mitochondria isolated from pig brains (in vitro model). Activity of monoamine oxidase (MAO) isoforms was determined radiochemically, activities of other mitochondrial enzymes were measured spectrophotometrically. Overall activity of the system of oxidative phosphorylation was measured electrochemically using high- resolution respirometry. Methods were modified to measure the same...

The adenylate cyclase toxin (CyaA) plays a key role in the virulence of Bordetella pertussis. CyaA penetrates CR3-expressing phagocytes and catalyzes the uncontrolled conversion of cytosolic ATP to the key second messenger molecule cAMP. This paralyzes the capacity of neutrophils and macrophages to kill bacteria by oxidative burst and opsonophagocytic mechanisms. Here we show that CyaA suppresses the production of bactericidal reactive oxygen and nitrogen species in neutrophils and macrophages, respectively. The inhibition of reactive oxygen species (ROS) production is most-likely achieved by the combined PKA-dependent inhibition of PLC and Epac-dependent dysregulation of NADPH oxidase assembly. Activation of PKA or Epac interfered with fMLP-induced ROS production and the inhibition of PKA partially reversed the CyaA-mediated inhibition of ROS production. CyaA/cAMP signaling then inhibited DAG formation, while the PIP3 formation was not influenced. These results suggest that cAMP produced by CyaA influences the composition of target membranes. We further show here that cAMP signaling through the PKA pathway activates the tyrosine phosphatase SHP-1 and suppresses the production of reactive nitrogen species (RNS) in macrophages. Selective activation of PKA interfered with LPS- induced iNOS expression...

Huntington's disease (HD) is an inherited autosomal dominant neurodegenerative disorder caused by an unstable expansion of the CAG repeat sequence within the huntingtin gene. Huntingtin associates with ubiquitin-proteasome system that ensures degradation of particular proteins including β-catenin which is an important molecule whose equilibrated degradation is necessary for the proper functioning of the Wnt signaling pathway. The binding of β-catenin to the destruction complex is altered in HD, leading to the toxic stabilization of β-catenin. The main goal of my thesis was to determine whether the accumulation of β-catenin due to the presence of mutant huntingtin is also characteristic of Liběchov minipigs, a large animal model of Huntington's disease stably expressing N-truncated human mutant huntingtin. Using immunoblot and specific antibodies, we have revealed age-dependent accumulation of mutant huntingtin in transgenic minipigs. Unlike endogenous huntingtin, no decrease of the level of mutant huntingtin was observed in the striatum of transgenic animals. Surprisingly, this was followed by a decrease of phosphorylated β-catenin. Nevertheless, our results demostrate the accumulation of β-catenin in mesenchymal stem cells isolated from the oldest boars during ontogenesis. Furthermore, we have revealed a...

Huntington's disease (HD) is an autosomal dominant hereditary neurodegenerative disease characterized by motor, cognitive and behavioral disorders. HD is caused by expansion of CAG triplet (cytosine-adenosine-guanine) located in a gene on the short arm of the fourth chromosome. This expansion encodes an aberrant polyglutamine chain in the protein huntingtin. Physiological and mutated huntingtin (in case of HD) are expressed in almost all tissues and influences many cellular functions. The prevalence of HD in population is about 1 per 10.000. The disease is currently incurable and its mechanisms are not sufficiently understood. Besides affecting the central nervous system HD also affects peripheral tissues, including skeletal muscles. HD disrupts mitochondrial function and damages oxidative phosphorylation system, which has the task of producing energy in the form of ATP in cells. Research of transgenic minipig model for HD could help elucidate the mechanisms of disease's pathogenesis and potential therapeutic strategy. In this diploma thesis, immunodetection with help of specific antibodies to detect changes in amount of 14 selected mitochondrial proteins in skeletal muscle tissue of three age groups of transgenic HD minipigs - 24, 36 and 48 months old was used. Gradual progression in reduced...

Tau protein, a microtubule-associated protein localized in axonal projections of neurons, is a key molecule in the pathology of Alzheimer's disease (AD), the most common cause of dementia in the elderly population. Tau belongs to the group of natively unfolded proteins without globular structure and is prone to numerous posttranslational modifications (PTMs). Under pathological conditions, abnormal PTMs and misfolding of tau protein occurs and leads to oligomerization and aggregation into paired helical filaments forming neurofibrillary tangles, the histopathological hallmark of AD. Currently available drugs applied in AD treatment can only slow the disease progression and those, which halt the AD-specific neurodegenerative processes, are still missing. Very promising and evolving therapeutic approach is immunotherapy, and even immunomodulation by administration of intravenous immunoglobulin (IVIG) products, a reservoir of natural antibodies from the plasma of healthy donors, has been already tested. The discovery of naturally occurring antibodies directed to tau (nTau-Abs) in body fluids of both AD and healthy subjects and their presence in IVIG begin the investigation of their therapeutic potential. Considering a wide range of possible modifications of tau and of various tau species (oligomers,...

Analysis of signaling cascade of protein kinase StkP in Streptococcus pneumoniae Streptococcus pneumoniae is not only an important human pathogen but also an appropriate model organism to investigate cell division in ovoid bacteria. This bacterium lacks both, NO and Min systems for selection of cell division site. Thus, the mechanism which determines the site of cell division is unknown. Additionally, the genome of S. pneumoniae encodes a single gene for eukaryotic-like serine/threonine protein kinase StkP and a single gene for eukaryotic-like serine/threonine protein phosphatase of PP2C type called PhpP. StkP is one of the main regulators of cell division. Cell division is probably affected by the phosphorylation of its substrates, which include, among others, cell division proteins FtsZ, FtsA, DivIVA, MacP, Jag/KhpB/EloR, and LocZ/MapZ. The aim of the first project of this dissertation thesis is determination of the function of protein LocZ in the cell division. In summary, locZ is not essential, however, it is involved in proper septum placement in S. pneumoniae and our data suggest that it is a positive regulator of Z-ring placement. Cells lacking LocZ are able to form Z-ring, but the Z-ring is spatially misplaced resulting in cell division defects, shape deformation, and generation of unequally sized,...

The complexes of the oxidative phosphorylation (OXPHOS) system in the inner mitochondrial membrane are organised into structural and functional super-assemblies, so-called supercomplexes. This type of organisation enables substrate channelling and hence improves the overall OXPHOS efficiency. ATP synthase associates into dimers and higher oligomers. Within the supercomplex of ATP synthasome, it interacts with ADP/ATP translocase (ANT), which exchanges synthesised ATP for cytosolic ADP, and inorganic phosphate carrier (PiC), which imports phosphate into the mitochondrial matrix. The existence of this supercomplex is generally accepted. Experimental evidence is however still lacking. In this thesis, structural interactions between ATP synthase, ANT and PiC were studied in detail. In addition, the interdependence of their expression was examined either under physiological conditions in rat tissues or using model cell lines with ATP synthase deficiencies of different origin. Specifically, they included mutations in the nuclear genes ATP5E and TMEM70 that code for subunit ε and the ancillary factor of ATP synthase biogenesis TMEM70, respectively, and a microdeletion at the interface of genes MT-ATP6 and MT-COX3 that impairs the mitochondrial translation of both subunit a of ATP synthase and subunit Cox3...