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Studies of minor capsid proteins of the mouse polyomavirus
Vít, Ondřej ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee)
Mouse polyomavirus (MPyV) is a small non-enveloped virus. Its capsid consists of 72 pentamers of the major capsid protein VP1. The central cavity of each VP1 pentamer contains one minor capsid protein, either VP2, or VP3. The minor capsid proteins are dispensable for capsid formation, but their presence is required for infection of the host cell, presumably because of their anticipated functions during virus entry. After internalization, MPyV virions traffic to endoplasmic reticulum (ER). VP2 and VP3 have been proposed to function as factors responsible for penetration of ER membranes, which is required for subsequent delivery of the viral DNA into the nucleus, a key step of the early phase of MPyV infection. Three hydrophobic domains were predicted in the sequence of VP2 and VP3. First in the unique Nterminal part of VP2, second and third in the common part of VP2 and VP3. The third domain corresponds to C-terminal VP1binding alpha-helix. It has been previously found in our laboratory, that VP2 and VP3 fused to N-terminus of EGFP, when expressed in mammalian cells, display properties similiar to the wild-type VP2 and VP3, namely affinity to intracellular membranes and high cytotoxicity. Expression plasmids carrying mutated VP2 and VP3 fused to Nterminus of EGFP were prepared to determine the hydrophobic...
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Molecular mechanisms and components controlling the Wnt signaling pathway output
Krausová, Michaela ; Kořínek, Vladimír (advisor) ; Drbal, Karel (referee) ; Bryja, Vítězslav (referee)
Beyond its essential roles in embryonic development, the Wnt-mediated signal transduction cascade is critically implicated in homeostasis of adult tissues. In the gastrointestinal epithelium, the threshold of active Wnt signaling is kept in a physiological range by a spectrum of regulatory networks and loops, thereby balancing the opposing processes of cell fate determination, proliferation and stem cell self-renewal. Furthermore, compelling evidence undoubtedly link an aberrant Wnt activity to the onset of bowel cancer. Understanding the principle causes and effects secondary to excessive Wnt signaling can provide valuable insights into the pathology of the malignant transformation of the colorectum. The proposed thesis attempts to focus on novel modes of the Wnt pathway modulation; both general and context-specific nuances of the Wnt level adjustment are thereby delineated. The results are presented in three distinct research publications and one review article. The first study examines the contribution of the distinct post-translational modifications, which the Wnt proteins undergo, to their proper processing, secretion and signaling activity. First, we investigated the sequential order and mutual interdependence of cysteine and serine-linked fatty acylation and N-linked glycosylation of murine...
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The role of fatty acylation in activity of proteins
Grobarčíková, Michaela ; Mašín, Jiří (advisor) ; Petráčková, Denisa (referee)
Post-translational modifications are covalent and generally enzyme-mediated modifications of proteins. These modifications can serve to create active forms of proteins and they can also expand the cellular repertoire of proteins derived from standard amino acids. Known post-translational modifications include for example phosphorylation, glycosylation, ubiquitination, proteolysis and also acylation discussed in more detail in this thesis. Acylation of proteins, the covalent attachment of an acyl group, is a very frequent protein modification. This reaction is typically mediated by specific acyl transferases and involves transport of an acyl group from a donor to an amino acid residue. A diverse spectrum of cellular proteins is post-translationally acylated and therefore become biologically active. This phenomenon occurs in bacterial toxins, which are important factors of the virulence of pathogenic bacteria. Protein lipidation regulates numerous biological pathways such as membrane targeting, protein secretion, cell signaling, and apoptosis. Posttranslational acylation is also required for Ras activity and many other cancer-causing proteins. Therefore, inhibitors of acyltransferases of these proteins are being tested as targets for antitumor drugs. In this work, findings about individual types of...
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The role of posttranslational modifications in action of bacterial toxins
Hudáčková, Kristýna ; Mašín, Jiří (advisor) ; Večerek, Branislav (referee)
Posttranslational modifications of proteins are a widespread mechanisms used by both prokaryotic and eukaryotic cells for increase the diversity of the proteome by the addition of functional groups, proteins, proteolytic cleavage of regulatory subunits, or degradation of entire proteins. These modifications include for example phosphorylation, glycosylation, acetylation, lipidation, ubiquitination or proteolysis and affect almost all aspects of cell biology and pathogenesis. Toxins produced by microorganisms are important virulence factors. Many of these bacterial toxins use posttranslational modification for their activation, as for example listeriolysin O, toxins of Bacillus anthracis or clostridial toxins. Large group of bacterial toxins activated by fatty acid are RTX (from Repeats-in-ToXin) toxins of Gram-negative pathogens, including Bordetella pertussis adenylate cyclase toxin or α-hemolysin secreted by uropathogenic Escherichia coli.
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Regulatory mechanisms of WNT signalling
Pospíchalová, Vendula
AB T mu hom dise β sign mu liga stab tran sign T the focu disc cate of t cell targ the inte con sec I sign BSTRACT The Wnt si lticellular o meostasis. A eases, most β-catenin is nalling). In ltiprotein c ands when t bilized and nscription f nalling is tig This thesis knowledge uses on seq cusses the enin signall the Wnt pa ls of intest geted mous thesis des eraction wit nditional Hi retory cell t In conclusi nalling path T ignalling pa organisms Accordingly notably can s a central m n unstimula complex and they engage d transloca factors and ghtly regula is based on e of the reg quential po positive ro ling outcom athway whic tinal epithe e strains th scribes unp th members ic1 deletion types and en ion, our fin hway in dev athway is o ensuring s y, mutations ncer. mediator of ated cells d degraded e their recep tes to the to drive th ated at vario n four origin gulation of sttranslation ole of nucle me. The third ch reduces lium. Final at enable st ublished da s of the Wn n in the inte nhanced tum ndings contr velopment an one of the m successful s in the pat f canonical W β-catenin d in the pro ptors, degrad nucleus t he transcrip ous levels b nal articles f the Wnt s nal process ear protein d study repo the levels o lly, the las tudying the ata on the nt pathway, estinal epith mourigenesi ributed to t...
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Kvantifikácia proteínov pomocou hmotnostnej spektrometrie a jej využitie pri sledovaní degeneračných zmien proteínu
Blaženiaková, Karina
Protein posttranslational modifications may play an important role in regulatory pathways but some of them are also the result of stress and protein ageing. This thesis Protein quantitation and its application in the monitoring of degenerative protein modifications briefly reviews major protein posttranslational modifications involved in degenerative processes. The experimental part utilises SRM-based targeted mass spectrometry to identify sites of stress-induced posttranslational modifications. Based on the available spectral libraries, a highly abundant barley seed protein was selected (Serpin-Z4) and the method for a targeted analysis of its tryptic peptides was optimised. Altogether, relative abundances of 14 peptides representing more than 50% of the protein sequence coverage were followed. The damage was induced by incubating barley seed powder at 99°C for 0.5-24 h or with hydrogen peroxide (0-30%). Abundances of seven and four peptides were significantly dicreased by heat and oxidative damage, respectively. The mapping of these peptides to the protein's 3D structure revealed that most of the altered peptides are exposed on the surface and thus present a likely target of stress-induced modifications. Finally, the SRM-based method was tested on food extracts.
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Plant tubulin code
Ničová, Klára ; Schwarzerová, Kateřina (advisor) ; Cvrčková, Fatima (referee)
Microtubules, which are made of polymers of α- and β-tubulin, are an integral part of the cytoskeleton. Both types of tubulin share a considerable sequential homology across eukaryotic organisms. Tubulins are encoded by relatively large gene families. The expression of these genes produces different tubulin isotypes, some of which may exhibit different properties. Tubulin isotypes can be further posttranslationally modified. The best known posttranslational modifications of tubulin include acetylation, phosphorylation, tyrosination, polyglutamylation and polyglycylation. The tubulin code arises from the combination of expression of different tubulin isotypes and their posttranslational modifications. As a consequence, microtubules in cells can be composed of a "mixture" of different tubulins with distinct functions and properties. Even though the existence of the tubulin code has been proven in every model organism, plants included, the precise understanding of the meaning of microtubules being composed of different tubulins is still subjected to research. Much of the research on the tubulin code has been carried out on animal models. In contrast, relatively little is known about the existence of the tubulin code in plants. This theses summarizes current knowledge on the localization and regulation...
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Studium ubiquitinace proteinů DELLA
Breineková, Alžběta
Posttranslational modifications (PTMs) of proteins represent fascinating extensions of the dynamic complexity of living cells' proteomes, but also present a solid obstacle in the proteome analysis. Identification and mapping of PTMs in proteins have improved dramatically, but to comprehend complex mechanisms and biological functions, one must address also a very low abundant proteins. Here, in this thesis entitled 'Analysis of DELLA protein ubiquitination' we demonstrate the use of a recombinant protein standard for the determination of in vivo modified peptides of the DELLA family protein RGA. The candidate peptide sequences were targeted in an SRM-based analysis to detect the ubiquitination site and the results of this analysis and that of an MS/MS data processing indicate that the modification is localized in the conserved N-terminal region of RGA protein.
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The role of posttranslational modifications of minor proteins and acetylation of microtubules in mouse polyomavirus infection
Mariničová, Zuzana ; Horníková, Lenka (advisor) ; Saláková, Martina (referee)
Mouse polyomavirus (MPyV) capsid is composed of the main capsid protein VP1 and minor capsid proteins VP2 and VP3. Minor proteins are not essential capsid assembly, but they are key for efficient viral infection. The first part of this thesis studies the modifications of VP2 and VP3, the deamidation of Asn at 253 of VP2 (137 of VP3) and N-terminal acetylation of Ala of VP3, which could be the cause of double bands for VP2 and VP3 on SDS-PAGE. Mutated genomes of MPyV N253D (Asn to Asp) and N253E (Asn to Glu) simulating deamidation and A117V (Ala to Val) with reduced acetylation were prepared previously. We prepared three isolations of the mutant viruses and we confirmed that the deamidation is the cause of the double bands. Mutant viruses were compared to the wild type in terms of efficiency of infection, but the role of deamidation could not be proven. Virus A117V is noninfectious either due to lowered acetylation or the substitution of amino acid at this position. This thesis also studies the role of -tubulin acetylation in the infection of MPyV. The role of -tubulin acetylation in viral infection is being investigated to find new antiviral strategies. Acetylation rises after MPyV infection, but this is not due to a change in mRNA expression of tubulin acetylating (TAT1) or deacetylating enzyme...
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