Laboratoř funkční biologie protist (Alena Panicucci Zíková)
African trypanosomes (T. brucei brucei, T. congolense, T. vivax), the model organisms of our laboratory, are extracellular parasites that, as the causative agents of African trypanosomiases, pose an enormous medical burden to humans and livestock and have a devastating impact on the economy. These deadly parasites undergo a complex life cycle between their mammalian hosts and insect vectors and face strikingly different environments with varying temperatures, pH, nutrients, immune responses etc.
In order to infect the host, replicate in the host environment, and differentiate into a transmissible life cycle form, the parasite's metabolism must rapidly adapt to the various nutrients provided by the host environment.
We focus on the single mitochondrion of the parasite, which undergoes one of the most extreme metabolic reorganizations known to date. From amino acid oxidation fueling oxidative phosphorylation to aerobic glycolysis, from fully developed cristae-containing reticulated mitochondrion to a single tubular organelle, from ATP-producing organelle to ATP-consuming organelle.
Our goal is to understand what signals (extracellular and intracellular) drive the metabolic remodeling of the parasite and the ultrastructural changes of the mitochondria and what are the molecular mechanisms behind them.
There are two important outcomes of our work. First, our findings can help in drug development. Second, our knowledge can shed light on the basic molecular processes that govern metabolic remodeling during cellular differentiation of all eukaryotic cells, including human stem cells, primary immune cells, and cancer cells.
Řešené výzkumné projekty
Mitochondrial respiratome of T. brucei
T. brucei mitochondrial respiratomeincludes mt inner membrane respiratory complexes I – IV together with FoF1 ATPsynthase/ATPase and important carriers e.g. ATP/ADP carrier (AAC) and phosphate carrier (PiC). There are several important reasons why to study this complex assembly of protein complexes in these unicellular flagellates; i) the composition of the mt respiratome is extreme as these protein complexes contain many novel and unique subunits; iii) the abundance, activity and function of the T. brucei respiratory complexes is developmentally regulated being fully active in the procyclic cells and absent or down-regulated in the bloodstream cells; iii) the mt FoF1 ATPase maintains the mt membrane potential (ΔΨ)in BF cells and thus possesses unique, essential and irreplaceable function in the infectious stage of the parasite.
FoF1 ATP synthase/ATPase function, structure, composition and regulation
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This project involves exploitation of FoF1 ATPsynthase/ATPase complex in T. brucei by solving the F1 ATPase crystal structure, by solving the overall FoF1 structure using cryo-EM, by mapping protein-protein interaction within the complex using yeast-two hybrid and yeast complementation system. Moreover, we are expanding our functional studies to define the FoF1 ATPase role in mt cristae biogenesis and thus microenvironment formation, and in shaping the permeability transition pore. As this enzyme exhibits dramatic differences compared to the conventional complexes found in mammalian, fungal and plant mitochondria, our findings have significant implications regarding the origin and evolution of this central player of cellular bioenergetics.
Bioenergetics of bloodstream mitochondrion
We are revisiting the proposed model of bloodstream mitochondrial bioenergetics which promotes dependence on glycolytic ATP and overall low activity of mt functions in the infectious stage of the parasites. It is plausible to speculate that bloodstream mitochondria might be active in ATP production by substrate phosphorylation and thus these mt biochemical pathways, which were thought to be inactive, are present, active and essential for the parasite. Therefore, the functional analysis of these pathways may reveal their potential as drug targets against T. brucei parasites.
Mechanism of mode of action of trypanocidal compounds in relation to the mitochondrial function
In collaboration with several scientific group, we are interested in identifying mode of action of some promising trypanocidal compounds. These compounds usually affect mt function. With a plethora of phenotypic assays we are able to decipher or point towards the drug target and mechanism of action.
