Biogenesis and Function of Cellular Organelles in Pathogenic Protozoa

Biogenesis and Function of Cellular Organelles in Pathogenic Protozoa

Prof. RNDr. Jan Tachezy, Ph.D.

Prof. RNDr. Jan Tachezy, Ph.D. — Project head

About us

This project is focused on functional studies of genes and their products which are associated with biogenesis and function of specialized organelles such as highly modified mitochondria called hydrogenosomes and mitosomes in some parasites. The research of these unique cellular structures brings not only fascinating discoveries on the eukaryotic diversity, but more importantly it provides potential for the development of new anti-parasitic strategies.

Objectives:

  • Mapping the unique cellular functions related to the pathogenicity and parasitic lifestyle in selected parasitic protozoa. The attention will mainly be paid to organisms adapted to environments with low oxygen levels (Trichomonas vaginalis, Giardia intestinalis, Entamoeba histolytica) and intracellular parasites such as microsporidia.
  • Search for and investigation of unique metabolic pathways and specific modifications of organelles and other subcellular structures in relation to the interactions between the host and the parasite, investigation of selected metabolic pathways and proteins with anti-parasitic potential.

The Hydrogenosomes

The hydrogenosomes are unusual organelles present in certain anaerobic unicellular eukaryotes such as trichomonads, cilliates, amoeboflagellates and fungi. They were discovered independetly at the Rockefeller University in New York (Lindmark and Muller, J. Biol. Chem., 248:7724-7728, 1973) and at the Charles University in Prague (Cerkasovova, A., Lukasova, G., Cerkasov J., and Kulda, J., J. Protozool., 20:537, 1973) more than 30 years ago.

However, the origin of these organelles is still question of debates:

  1. Are they derivatives of mitochondria?
  2. Did they evolve independently from anaerobic bacteria?
  3. Did they derive from peroxisomes?
  4. Did hydrogenosomes and mitochondria evolve from a common proteobacterial ancestor?

Mitosome

Mitosome is a name given to the organelle of mitochondrial origin present in type I "amitochondrial" eukaryotes. It has been described in Entamoeba histolytica and later in microsporidian Trachipleistophora hominis. Presence of mitosome as well as genes of mitochondrial origin in genomes of these organisms suggests that contemporary amitochondriates ones harboured mitochondria, and do not represent lineages, which evolved before acquisition of mitochondria. Recently, mitosome was identified also in Giardia intestinalis, an amitochondrial protist, which was considered to be early branching primary amitochondrial eukaryote.

The mitochondrial origin of mitosome is supported by

  1. presence of two membranes surrounding these organelles,
  2. localization of proteins of iron sulfur cluster assembly machinery within these organelles (IscU, IscS, ferredoxin),
  3. targeting of proteins into the mitosome by means of N-terminal leader sequences with similar properties of mitochondrial leader sequences,
  4. FeS cluster assembly activity idetified in mitosome-rich cell fraction.

Localization of IscU in mitosome of Giardia intestinalis

Fluorescent Microscopy

Fluorescent Microscopy
Electron Microscopy

Resistance to Metronidazole

Metronidazole is a drug of choice for treatment of trichomoniasis as well as other infections caused by anaerobic pathogens. The selective toxicity of metronidazole is based on its reductive activation by low-redox electron carriers such as ferredoxins. In T. vaginalis the drug is activated within hydrogenosomes containing ferredoxin-linked electron chain. The electrons are genereted by oxidative decarboxylation of pyruvate or malate by activity of pyruvate: ferredoxin oxidoreductase or NAD-dependent malic enyzme, respectively. Under anaerobiosis, the terminal acceptor of electrons is hydrogenase producing molecular hydrogen, while under aerobic conditions the electrons are accepted by oxygen. Metronidazole compete for the electrons with hydrogenase or oxygen, which results in its reduction and release of cytotoxic nitroradicals.

There are two type of metronidazole resistance:

  • Aerobic resistance is based on impaired oxygen scavenging system in hydrogenosomes. This type of resistance is found in strains isolated from patients refractory to standard treatment.
  • Anaerobic resistance is based on loss of electron generating pathways responsible for the drug activation. Anaerobicaly resistant strain were developed only in vitro. It seems that aerobic and anaerobic resistance are two steps of the common process.

Tritrichomonas foetus and Tritrichomonas suis: two different names, two differnet hosts but only a single species?

T. foetus is a well know parasite causing sexually transmitted disease in cattle, while T. suis is considered to be a commensal of pigs. In Europe,

T. foetus was almost eradicated, while T. suis is still a common organisms.

However,

Their morphology is identical:

  • No differences by PCR fingerpriting:
  • No difference in ITS1-5.8rRNA-ITS-2 sequences: Accession Numbers AY 055799, AY055800 (NCBI).

Genomics and Proteomics

Analysis of Hydrogenosome Proteome / Analysis of Mitosome Proteome

In collaboration with proteomic groups at the University of Birmingham, Alabama, USA and Jacques Monod Institute, France, we initiated investigation on Trichomonas vaginalis hydrogenosome proteome.

News

Publications

2019

Makki, A., Rada, P., Zarsky, V., Kereiche, S., Kovacik, L., Novotny, M., Jores, T., Rapaport, D. and Tachezy, J. (2019) Triplet-pore structure of a highly divergent TOM complex of hydrogenosomes in Trichomonas vaginalis. PLoS Biol, 17, e3000098.

2018

Rada, P., Makki, A., Zarsky, V. and Tachezy, J.: Targeting of Tail-Anchored Proteins to Trichomonas Vaginalis Hydrogenosomes. Mol Microbiol (2018).

♯ SIM              ♯ STED           ♯ confocal       ♯ EM chemical fixation

Stafkova, J., Rada, P., Meloni, D. et al.: Dynamic Secretome of Trichomonas Vaginalis : Case Study of β-amylases. Mol & Cell Proteom 17, 304-320 (2018).

♯ SIM             ♯ TEM

2011

Rada P, Doležal P, Jedelský PL, Bursac D, Perry AJ, Šedinová M, Smíšková K, Novotný M, Beltrán NC, Hrdý I, Lithgow T, Tachezy J. The core components of organelle biogenesis and membrane transport in the hydrogenosomes of Trichomonas vaginalis. PLoS One. 2011

Team

Prof. RNDr. Jan Tachezy, Ph.D.

Prof. RNDr.
Jan Tachezy, Ph.D.

Vice-Chairman of the Board, Co-ordinator of Cellular Biology and Virology Research Programme

jan.tachezy@natur.cuni.cz
+420325873908
Doc. RNDr. Ivan Hrdý, Ph.D.

Doc. RNDr.
Ivan Hrdý, Ph.D.

Head of Department of Parasitology of the Faculty of Science CUNI

ivan.hrdy@natur.cuni.cz
+420325873912
Mgr. Petr Rada, Ph.D.

Mgr.
Petr Rada, Ph.D.

Assistant Professor

petr.rada@natur.cuni.cz
+420325873948
Mgr. Vojtěch Žárský

Mgr.
Vojtěch Žárský

PhD student

zarskyv@gmail.com
+420325873946
RNDr. Zdeněk Verner, Ph.D.

RNDr.
Zdeněk Verner, Ph.D.

Postdoctoral researcher

zdenek.verner@natur.cuni.cz
+420325873948
MSc. Abhijith Makki

MSc.
Abhijith Makki

Phd student

abhijith.makki@natur.cuni.cz
+420325873946
Nadine Zimmann

Nadine Zimmann

PhD Student

nadine.hohensee@natur.cuni.cz
+420325873948
M.Sc. Tien Le

M.Sc.
Tien Le

PhD student

tien.le@natur.cuni.cz
+420325873946
Michaela Marcinčiková

Michaela Marcinčiková

Laboratory Manager

michaela.marcincikova@natur.cuni.cz
+420325873951

Ravi Kumar Narayanasamy

Postdoctoral researcher

narayanr@natur.cuni.cz
+420325873948
Mgr. Tamara Smutná, Ph.D.

Mgr.
Tamara Smutná, Ph.D.

Postdoctoral researcher

tamara.smutna@natur.cuni.cz
+420325873950

Teaching

Join with us the study of patogeny protists , which are important in human or veterinary medicine (trichomonads, giardia, Entamoeba histolytica, trypanosomes) and other protists, mainly flagellates, which are interesting through their fylogenetics or through function of their organells.

Offered topics

thesis author thesis name thesis type
Prof. Jan Tachezy Treatment of human trichomoniasis: comparative proteomics of Trichomonas vaginalis strains of various susceptibility to metronidazole Diploma Thesis
Prof. Jan Tachezy Functional study of proteins involved in FeS cluster assembly in mitosomes of Giardia intestinalis Diploma thesis
Prof. Jan Tachezy Utilization of pentoses in energy metabolism of Mastigamoeba balamuthi Diploma Thesis
Prof. Jan Tachezy Biogenesis of hydrogenosomes and mitosomes Diploma Thesis
Prof. Jan Tachezy Role of exosomes in virulence of Trichomonas vaginalis Diploma Thesis
Prof. Jan Tachezy Changes in secretome of Trichomonas vaginalis upon interaction with Lactobacillus sp. Diploma Thesis
Prof. Jan Tachezy Pathogenic tritrichomonads in domestic animal Bachelor thesis
Ivan Hrdý Mechanisms of metronidazole activation in trichomonad hydrogenosome Diploma thesis
Ivan Hrdý Glycolytic enzymes in hydrogenosomes? Study of phosphofructokinases in Trichomonas vaginalis Diploma thesis
Ivan Hrdý Ferredoxins: structure and function Bachelor Thesis
Ivan Hrdý Moonlighting proteins: multifunctional enzymes in parasites Bachelor Thesis