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Chromosomes of parasitic protist Trichomonas vaginalis
Zubáčová, Zuzana ; Tachezy, Jan (advisor) ; Alsmark, Cecília (referee) ; Vanáčová, Štěpánka (referee)
Charles University in Prague Faculty of Science Programme of study: Parasitology Abstract of Ph.D. thesis Chromosomes of parasitic protist Trichomonas vaginalis Zuzana Zubáčová, MSc. Supervisor: Prof. RNDr. Jan Tachezy, Ph.D. Praha, 2011 Abstract Genome sequencing and associated proteome projects has revolutionized research in the field of molecular parasitology. Progress in sequencing of parasite as well as free-living species enables comparative and phylogenetic studies and provides important data sets for understanding of basic biology and identification of new drug targets. The genome sequencing of Trichomonas vaginalis revealed surprisingly large genome size of this organism (~160 Mb) that resulted from expansion of various repetitive elements, specific gene families and large scale genome duplication. I studied genome sizes of other nine selected species from Trichomonadea group to find whether other trichomonads have undergone similar genome expansion. The measurement of nuclear DNA content by flow cytometry revealed relatively large DNA content in all tested species although within a broad range (86-177 Mb). The largest genomes were observed in the Trichomonas and Tritrichomonas genera while Tetratrichomonas contains the smallest genome. The genome sizes correlated with the cell volume however no...
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Reductive Evolution of Mitochondria - Related Organelles in Anaerobic Protist
Rada, Petr ; Tachezy, Jan (advisor) ; Embley, Martin (referee) ; Eliáš, Marek (referee)
Charles University in Prague, Faculty of Science Department of Parasitology Ph.D. study program: Parasitology Abstract of the Ph.D. Thesis Reductive Evolution of Mitochondria - Related Organelles in Anaerobic Protist Petr Rada Supervisor: Prof. RNDr. Jan Tachezy,Ph.D. Advisor: Doc. RNDr. Ivan Hrdý, Ph.D. Praha, 2011 1 ABSTRACT Trichomonas vaginalis and Giardia intestinalis are parasitic protists of the Excavata group. Both contain anaerobic forms of mitochondria called hydrogenosomes (Trichomonas) and mitosomes (Giardia). Hydrogenosomes produce hydrogen and ATP by substarte level phosphorylation and mitosomes represent the highly-reduced form of mitochondria that do not participate in cellular energy metabolism and ATP generation. Both types of organelles lost the majority of mitochondrial pathways and their genomes during the mitochondrion to hydrogenosome transition. Consequently, hydrogenosomes and mitosomes facilitate translocation of nuclearly encoded proteins into the matrix of the organelle as well as exchange of metabolites and ions across their membranes. Little is known about the membrane machineries required for the biogenesis of the organelle and metabolite exchange and the limited knowledge of mitosomal proteomes has been mostly gained from genomic analysis and localization studies of a few...
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Iron-sulfur proteins and the role of iron in the gene expression of Trichomonas vaginalis
Horváthová, Lenka ; Tachezy, Jan (advisor) ; Rasoloson, Dominique (referee) ; Vyoral, Daniel (referee)
Iron is an essential nutrient for the parasitic protist Trichomonas vaginalis as a component of iron-sulfur (FeS) proteins that are indispensable for energy metabolism of the parasite. The FeS clusters are formed by FeS cluster (ISC) assembly machinery that resides, together with a number of FeS proteins, in Trichomonas hydrogenosomes. These double-membrane bound organelles, which are related to mitochondria, metabolize malate and pyruvate and produce ATP and molecular hydrogen. To obtain more complete information about hydrogenosomal pathways with particular focus on FeS proteins and ISC machinery, we participated on analysis of T. vaginalis genome sequence. To predict hydrogenosomal localization of putative gene products, we developed an application "Hunter" for the in silico searching for N-terminal presequences that are required for protein targeting into the hydrogenosomes. This approach substantially contributed to annotate genes coding for hydrogenosomal proteins that provided base for construction of novel map of hydrogenosomal metabolism as well as for following proteomic studies. Investigation of hydrogenosomal proteins led to identification of three members of Hyd machinery that is required for the maturation of the specific FeS cluster of hydrogenases named H cluster. T. vaginalis is,...
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Pathogenic trichomonads in domestic animals
Vobořilová, Pavlína ; Tachezy, Jan (advisor) ; Čepička, Ivan (referee)
Pathogenic trichomonads of domestic animals are anaerobic protozoa found in the gastrointestinal and reproductive tract. They are responsible for serious diseases, which result in economic losses in agriculture. Cochlosoma anatis parasitizes in the intestine of birds, where it causes so-called runting syndrome and enteritis. Trichomonas gallinae is found in the gastrointestinal tract of pigeons and represents a dangerous infection of wild migratory birds and endangered birds of prey. Histomonas meleagridis is the causative agent of the best known, fatal and very redoubtable disease of turkeys and hens, so-called "blackhead disease". Tritrichomonas foetus is the causative agent of the most important sexually transmitted infection, tritrichomonosis in cattle, which causes significant economic losses in global beef production. T. foetus was recently identified as the causal agent of diarrheal disease in cats. Also Tritrichomonas mobilensis was recently described as a new species which probably disrupts the intestinal mucosa of squirrel monkeys. This work includes the general characteristics of these species and a detailed summary of the current knowledge on the diseases they are causing. The description covers the issue of sources and disease transmission, host specificity of the parasite and...
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Protein import into mitochondria and peroxisomes of parasitic protists
Žárský, Vojtěch ; Tachezy, Jan (advisor) ; Hampl, Vladimír (referee)
The presented thesis includes three related projects, that are linked by a common interest in the evolution of eukaryotic organelles and machineries that import proteins into these compartments. The first project considers the possibility of peroxisomes (eukaryotic organelles known in aerobic organisms) being conserved in two related anaerobic protists: a free-living amoeba Mastigamoeba balamuthi and a parasite Entamoeba histolytica. The most important hint for the presence of peroxisomes was the discovery of proteins that are homologous to known components of the peroxisomal protein import machinery. The second project aims to characterize the unknown protein translocase of the inner membrane (TIM) in the mitosomes (extremely reduced mitochondria) of an anaerobic protozoan Giardia intestinalis. We have discovered an important subunit of the mitosomal translocase (Tim44), which usually tethers the Hsp70/PAM (presequence translocase-associated motor) complex to the TIM translocon. The last project shows that the protein translocase of the outer mitochondrial membrane in trypanosomatids is related to a typical eukaryotic channel Tom40. This finding is important because the absence of Tom40 was previously considered an ancestral feature of trypanosomatids.
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Evolution of eukaryotic ABC transporters
Žárský, Vojtěch ; Doležal, Pavel (referee) ; Tachezy, Jan (advisor)
In the past twenty years there has been a lot of research done on ABC transporters. This group of membrane transporters was recognized as highly important due to its ubiquity in living organisms and due to the involvement of some of the ABC transporters in multidrug resistance of cancer cells and pathogens against chemotherapeutics. This medical aspect of ABC transporters was naturally the most important one for the majority of researchers. On the other hand, the biological aspects and evolution of many ABC transporters remained untouched. In this work I give an overview of ABC transporters of parasitic protozoa and focus on the evolutionary aspect of eukaryotic transporters and on mitochondrial ABC transporters, which are the most conserved ones among eukaryotic ABC transporters.
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The essential processes of FeS cluster assembly and mitochondrial protein import in parasitic protists
Šmíd, Ondřej ; Tachezy, Jan (advisor) ; Hampl, Vladimír (referee) ; DYALL, Sabrina D. (referee)
CONCLUSIONS Mitochondria appear to be vital organelles for all eukaryotic organisms known to date. A large body of evidence strongly indicates that hydrogenosomes and mitosomes, the organelles of anaerobic or intracellular parasitic protists lacking the "typical" mitochondria, are only a variation on the mitochondrial theme. However, even though the three organelles are evolutionarily the same entity, remarkable differences exist between them that reflect the adaptation of the organisms to their specific niches. In the thesis I tried to unravel some aspects of the essential mitochondrial processes of FeS cluster assembly and mitochondrial protein import in parasitic protists T. brucei and G. intestinalis. We investigated the function of the T. brucei cysteine desulfurase IscS and the scaffold protein IscU. We demonstrated that the two proteins are essential for FeS cluster formation and consequently the viability of the procyclic stage of T. brucei. Even though both IscS and IscU were specifically localized to the mitochondrion, their deficient expression affected the maturation of FeS proteins operating not only in the mitochondrion, but also in the cytosol. This indicates that a crucial part of FeS cluster assembly is localized to the mitochondrion of T. brucei. One of the major differences between the T....
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