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Bacterial proteins in the biogenesis of mitochondria of unicellular eukaryotes.
Petrů, Markéta ; Doležal, Pavel (advisor) ; Embley, Martin (referee) ; Hashimi, Hassan (referee)
in English Formation of mitochondria by the conversion of a bacterial endosymbiont is the fundamental moment in the evolution of eukaryotes. An integral part of the organelle genesis was the displacement of the endosymbiont genes to host nucleus and simultaneous creation of new pathways for delivery of proteins synthesized now in the host cytoplasm. Resulting protein translocases are complexes combining original bacterial components and eukaryote-specific proteins. In addition to these novel protein import machines, some components of the original bacterial secretory pathways have remained in the organelle. While the function of a widely distributed mitochondrial homolog of YidC, Oxa1, is well understood, the role of infrequent components of Sec or Tat translocases has not yet been elucidated. So far, more attention has been paid to their abundant plastid homologs, which assemble photosynthetic complexes in the thylakoid membrane. In the thesis, the structure and function of prokaryotic YidC, Sec and Tat machineries and their eukaryotic homologs are described. By comparing both organelles of the endosymbiotic origin, the hypothesis is drawn on why these translocases have been more "evolutionary successful" in plastids than in mitochondria.
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Bacterial proteins in the biogenesis of mitochondria of unicellular eukaryotes.
Petrů, Markéta
in English Formation of mitochondria by the conversion of a bacterial endosymbiont is the fundamental moment in the evolution of eukaryotes. An integral part of the organelle genesis was the displacement of the endosymbiont genes to host nucleus and simultaneous creation of new pathways for delivery of proteins synthesized now in the host cytoplasm. Resulting protein translocases are complexes combining original bacterial components and eukaryote-specific proteins. In addition to these novel protein import machines, some components of the original bacterial secretory pathways have remained in the organelle. While the function of a widely distributed mitochondrial homolog of YidC, Oxa1, is well understood, the role of infrequent components of Sec or Tat translocases has not yet been elucidated. So far, more attention has been paid to their abundant plastid homologs, which assemble photosynthetic complexes in the thylakoid membrane. In the thesis, the structure and function of prokaryotic YidC, Sec and Tat machineries and their eukaryotic homologs are described. By comparing both organelles of the endosymbiotic origin, the hypothesis is drawn on why these translocases have been more "evolutionary successful" in plastids than in mitochondria.
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Bacterial proteins in the biogenesis of mitochondria of unicellular eukaryotes.
Petrů, Markéta
in English Formation of mitochondria by the conversion of a bacterial endosymbiont is the fundamental moment in the evolution of eukaryotes. An integral part of the organelle genesis was the displacement of the endosymbiont genes to host nucleus and simultaneous creation of new pathways for delivery of proteins synthesized now in the host cytoplasm. Resulting protein translocases are complexes combining original bacterial components and eukaryote-specific proteins. In addition to these novel protein import machines, some components of the original bacterial secretory pathways have remained in the organelle. While the function of a widely distributed mitochondrial homolog of YidC, Oxa1, is well understood, the role of infrequent components of Sec or Tat translocases has not yet been elucidated. So far, more attention has been paid to their abundant plastid homologs, which assemble photosynthetic complexes in the thylakoid membrane. In the thesis, the structure and function of prokaryotic YidC, Sec and Tat machineries and their eukaryotic homologs are described. By comparing both organelles of the endosymbiotic origin, the hypothesis is drawn on why these translocases have been more "evolutionary successful" in plastids than in mitochondria.
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Bacterial proteins in the biogenesis of mitochondria of unicellular eukaryotes.
Petrů, Markéta ; Doležal, Pavel (advisor) ; Embley, Martin (referee) ; Hashimi, Hassan (referee)
in English Formation of mitochondria by the conversion of a bacterial endosymbiont is the fundamental moment in the evolution of eukaryotes. An integral part of the organelle genesis was the displacement of the endosymbiont genes to host nucleus and simultaneous creation of new pathways for delivery of proteins synthesized now in the host cytoplasm. Resulting protein translocases are complexes combining original bacterial components and eukaryote-specific proteins. In addition to these novel protein import machines, some components of the original bacterial secretory pathways have remained in the organelle. While the function of a widely distributed mitochondrial homolog of YidC, Oxa1, is well understood, the role of infrequent components of Sec or Tat translocases has not yet been elucidated. So far, more attention has been paid to their abundant plastid homologs, which assemble photosynthetic complexes in the thylakoid membrane. In the thesis, the structure and function of prokaryotic YidC, Sec and Tat machineries and their eukaryotic homologs are described. By comparing both organelles of the endosymbiotic origin, the hypothesis is drawn on why these translocases have been more "evolutionary successful" in plastids than in mitochondria.
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Protein Import into the Mitosomes of Giardia intestinalis
Martincová, Eva ; Doležal, Pavel (advisor) ; Novotný, Marian (referee)
Mitochondrion is believed to be an ubiquitous organelle which occurred about 1,5 billion years ago by a single endosymbiotic event. Mitochondria is mostly dependent on the protein import from cytosol thus the establishment of protein import machinery was essential for seizing the new endosymbiont. Possibilities of studying the evolution of protein import machineries are quite limited given that no "free living" mitochondria or amitochondriate organisms are known nowadays. One alternative is to study mitochondrial secondary reductive evolution of anaerobic parasitic protists. Giardia intestinalis is flagellated protozoan living in microaerofilic environment of the small intestine. It containes one of the most reduced mitochondrion (mitosome) described so far. Hence it serves as a great model for studying mitochondrial evolution. Although it is well understood that all mitosomal proteins are transported from cytosol, many aspects of protein import pathway remain elusive. While the main channel Tom40 is present in the outer membrane, two other main translocases (Sam50 which is required for betta-barrel assembly in the outer membrane and Tim17/22/23 which is essential for protein translocation through the inner membrane) have not been identified so far. Protein translocation through Tim17/22/23 channel...
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Transport of proteins into secondary plastids
Vanclová, Anna ; Hampl, Vladimír (advisor) ; Doležal, Pavel (referee)
Secondary plastids can be found in many unrelated groups of organisms among three supergroups - Excavata, Rhizaria and Chromista. Primary plastids in contrast are unique and defining feature of the Archaeplastida supergroup. Secondary plastids have arisen through several independent endosymbiotic events, in which engulfment of an eukaryotic cell containing primary plastid occured and its reduction and integration by transfering bulk of their genome into host nucleus occured. Crucial difference between primary and secondary plastids is number of surrounding membranes which need to be crossed by nucleus-encoded proteins which is higher in secondary plastids. Mechanisms of protein transport into secondary plastids are therefore more complicated and more molecules and signals partake in these mechanisms. Diversity of secondary plastid-bearing organisms notably contrasts with the fact that the transport pathways and molecules they use often share mechanism of function and origin. These similarities probably reflect general principles of cell biology and not phylogeny.
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