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The role of c14orf2 protein in structure and function of mammalian ATP synthase
Ho, Dieu Hien ; Pecina, Petr (advisor) ; Panicucci Zíková, Alena (referee)
The F1Fo-ATP synthase (EC 3.6.3.14) is a key enzyme of the mitochondrial oxidative phosphorylation system (OXPHOS) - using the proton gradient generated by the respiratory chain it synthetizes approximately 90 % of cellular ATP. The subunit arrangement of its Fo domain has not been yet described in detail. At present, the research on ATP synthase research is focused mostly on revealing the structure of the proton channel a so that it is possible to precisely define the molecular mechanism of the ATP synthase rotation generation. The role of the supernumery subunits of Fo domain represents another unresolved issue. These proteins specific for eukaryotic ATP synthases are not essential for synthetic activity, instead they are putatively involved in assembly or stabilization of the enzyme complex. One of such subunits is the nuclear encoded MLQ protein (or also 6.8 kDa proteolipid or MP68), which is conserved only in vertebrates. The aim of this diploma thesis was to reveal the role of this subunit in the structure, assembly and function of the F1Fo-ATP synthase. For these purposes, cellular model of the HEK293 line with the deficiency of the MLQ protein was established employing the CRISPR/Cas9 method with paired nickases (the knock-out MLQ, MLQ KO) as part of the thesis. Three chosen MLQ KO lines...
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Molecular consequences of electron transport chain deficiency in proliferating and quiescent cells
Magalhães Novais, Silvia Carina ; Rohlena, Jakub (advisor) ; Panicucci Zíková, Alena (referee) ; Eelen, Guy (referee)
Oxidative phosphorylation (OXPHOS) system is best known for producing ATP in mitochondria. As a major metabolic hub, OXPHOS also supports other biological functions that are unrelated to ATP synthesis. Are these additional roles of OXPHOS unique to different cell states, such as to proliferation and quiescence, two of the most contrasting states of a mammalian cell? In this thesis we used genetic models of OXPHOS deficiency to show that in proliferating cells and in tumors OXPHOS primarily supports biosynthesis of nucleotides, whereas in quiescent cells OXPHOS provides oxidative stress resistance. Mechanistically, in growing tumors OXPHOS drives dihydroorotate dehydrogenase (DHODH), an enzyme crucial for de novo synthesis of pyrimidines. Complex II of OXPHOS also acts as a sensor of mitochondrial dysfunction and regulates pyrimidine synthesis for energy conservation. In contrast, in quiescent cells OXPHOS maintains autophagy by continuous low level ROS generation and together with the antioxidant defense provides constitutive oxidative stress protection. In summary, beyond ATP production OXPHOS has additional vital roles tailored to the particular requirements of quiescence and proliferation, with relevance for pathophysiology in cancer and vascular biology.
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Structural and Functional Interactions of Mitochondrial ADP-Phosphorylating Apparatus
Nůsková, Hana ; Houštěk, Josef (advisor) ; Kolarov, Jordan (referee) ; Kuda, Ondřej (referee) ; Panicucci Zíková, Alena (referee)
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...
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The role of c14orf2 protein in structure and function of mammalian ATP synthase
Ho, Dieu Hien ; Pecina, Petr (advisor) ; Panicucci Zíková, Alena (referee)
The F1Fo-ATP synthase (EC 3.6.3.14) is a key enzyme of the mitochondrial oxidative phosphorylation system (OXPHOS) - using the proton gradient generated by the respiratory chain it synthetizes approximately 90 % of cellular ATP. The subunit arrangement of its Fo domain has not been yet described in detail. At present, the research on ATP synthase research is focused mostly on revealing the structure of the proton channel a so that it is possible to precisely define the molecular mechanism of the ATP synthase rotation generation. The role of the supernumery subunits of Fo domain represents another unresolved issue. These proteins specific for eukaryotic ATP synthases are not essential for synthetic activity, instead they are putatively involved in assembly or stabilization of the enzyme complex. One of such subunits is the nuclear encoded MLQ protein (or also 6.8 kDa proteolipid or MP68), which is conserved only in vertebrates. The aim of this diploma thesis was to reveal the role of this subunit in the structure, assembly and function of the F1Fo-ATP synthase. For these purposes, cellular model of the HEK293 line with the deficiency of the MLQ protein was established employing the CRISPR/Cas9 method with paired nickases (the knock-out MLQ, MLQ KO) as part of the thesis. Three chosen MLQ KO lines...
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Structural and Functional Interactions of Mitochondrial ADP-Phosphorylating Apparatus
Nůsková, Hana ; Houštěk, Josef (advisor) ; Kolarov, Jordan (referee) ; Kuda, Ondřej (referee) ; Panicucci Zíková, Alena (referee)
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...
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