Naegleria fowleri is a single-cell organism living in warm freshwater that can become a deadly human pathogen known as a brain-eating amoeba. The condition caused by N. fowleri, primary amoebic meningoencephalitis, is usually a fatal infection of the brain with rapid and severe onset. Iron is a common element on earth and a crucial cofactor for all living organisms. However, its bioavailable form can be scarce in certain niches, where it becomes a factor that limits growth. To obtain iron, many pathogens use different machineries to exploit an iron-withholding strategy that has evolved in mammals and is important to host-parasite interactions. The present study demonstrates the importance of iron in the biology of N. fowleri and explores the plausibility of exploiting iron as a potential target for therapeutic intervention. We used different biochemical and analytical methods to explore the effect of decreased iron availability on the cellular processes of the amoeba. We show that, under iron starvation, nonessential, iron-dependent, mostly cytosolic pathways in N. fowleri are downregulated, while the metal is utilized in the mitochondria to maintain vital respiratory processes. Surprisingly, N. fowleri fails to respond to acute shortages of iron by inducing the reductive iron uptake system that seems to be the main iron-obtaining strategy of the parasite. Our findings suggest that iron restriction may be used to slow the progression of infection, which may make the difference between life and death for patients.

• MeSH
• buněčné dýchání MeSH
• fyziologická adaptace * MeSH
• mitochondrie metabolismus   MeSH
• Naegleria fowleri genetika   metabolismus   MeSH
• regulace genové exprese * MeSH
• stopové prvky metabolismus   MeSH
• železo metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• stopové prvky MeSH
• železo MeSH

Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular processes. The biogenesis of Fe-S clusters in the cytosol and their insertion into proteins is accomplished through the cytosolic iron-sulphur protein assembly (CIA) machinery. The early- and middle-acting modules of the CIA pathway concerned with the assembly and trafficking of Fe-S clusters have been previously characterised in the parasitic protist Trypanosoma brucei. In this study, we applied proteomic and genetic approaches to gain insights into the network of protein-protein interactions of the late-acting CIA targeting complex in T. brucei. All components of the canonical CIA machinery are present in T. brucei including, as in humans, two distinct CIA2 homologues TbCIA2A and TbCIA2B. These two proteins are found interacting with TbCIA1, yet the interaction is mutually exclusive, as determined by mass spectrometry. Ablation of most of the components of the CIA targeting complex by RNAi led to impaired cell growth in vitro, with the exception of TbCIA2A in procyclic form (PCF) trypanosomes. Depletion of the CIA-targeting complex was accompanied by reduced levels of protein-bound cytosolic iron and decreased activity of an Fe-S dependent enzyme in PCF trypanosomes. We demonstrate that the C-terminal domain of TbMMS19 acts as a docking site for TbCIA2B and TbCIA1, forming a trimeric complex that also interacts with target Fe-S apo-proteins and the middle-acting CIA component TbNAR1.

• MeSH
• cytosol metabolismus   MeSH
• interakční proteinové domény a motivy MeSH
• konformace proteinů MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• proteiny obsahující železo a síru chemie   metabolismus   MeSH
• protozoální proteiny chemie   metabolismus   MeSH
• Trypanosoma brucei brucei růst a vývoj   metabolismus   MeSH
• trypanozomiáza metabolismus   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny obsahující železo a síru MeSH
• protozoální proteiny MeSH

The majority of established model organisms belong to the supergroup Opisthokonta, which includes yeasts and animals. While enlightening, this focus has neglected protists, organisms that represent the bulk of eukaryotic diversity and are often regarded as primitive eukaryotes. One of these is the "supergroup" Excavata, which comprises unicellular flagellates of diverse lifestyles and contains species of medical importance, such as Trichomonas, Giardia, Naegleria, Trypanosoma and Leishmania. Excavata exhibits a continuum in mitochondrial forms, ranging from classical aerobic, cristae-bearing mitochondria to mitochondria-related organelles, such as hydrogenosomes and mitosomes, to the extreme case of a complete absence of the organelle. All forms of mitochondria house a machinery for the assembly of Fe-S clusters, ancient cofactors required in various biochemical activities needed to sustain every extant cell. In this review, we survey what is known about the Fe-S cluster assembly in the supergroup Excavata. We aim to bring attention to the diversity found in this group, reflected in gene losses and gains that have shaped the Fe-S cluster biogenesis pathways.

• Klíčová slova
• Evolution, Excavata, Fe–S cluster, Mitochondria,
• MeSH
• Eukaryota cytologie   metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• proteiny obsahující železo a síru metabolismus   MeSH
• železo metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• proteiny obsahující železo a síru MeSH
• železo MeSH

BACKGROUND: Kinetoplastea is a diverse protist lineage composed of several of the most successful parasites on Earth, organisms whose metabolisms have coevolved with those of the organisms they infect. Parasitic kinetoplastids have emerged from free-living, non-pathogenic ancestors on multiple occasions during the evolutionary history of the group. Interestingly, in both parasitic and free-living kinetoplastids, the heme pathway-a core metabolic pathway in a wide range of organisms-is incomplete or entirely absent. Indeed, Kinetoplastea investigated thus far seem to bypass the need for heme biosynthesis by acquiring heme or intermediate metabolites directly from their environment. RESULTS: Here we report the existence of a near-complete heme biosynthetic pathway in Perkinsela spp., kinetoplastids that live as obligate endosymbionts inside amoebozoans belonging to the genus Paramoeba/Neoparamoeba. We also use phylogenetic analysis to infer the evolution of the heme pathway in Kinetoplastea. CONCLUSION: We show that Perkinsela spp. is a deep-branching kinetoplastid lineage, and that lateral gene transfer has played a role in the evolution of heme biosynthesis in Perkinsela spp. and other Kinetoplastea. We also discuss the significance of the presence of seven of eight heme pathway genes in the Perkinsela genome as it relates to its endosymbiotic relationship with Paramoeba.

• Klíčová slova
• Endosymbiosis, Evolution, Heme, Kinetoplastea, Lateral gene transfer, Paramoeba pemaquidensis, Perkinsela, Prokinetoplastina,
• MeSH
• biologická evoluce MeSH
• Eukaryota klasifikace   fyziologie   MeSH
• fylogeneze MeSH
• hem metabolismus   MeSH
• Kinetoplastida klasifikace   genetika   fyziologie   MeSH
• přenos genů horizontální MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hem MeSH