Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane. Recent findings have demonstrated that components of the T2SS are localized in mitochondria of some eukaryotic lineages, and their behavior is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). This review focuses on recent advances in the field and discusses open questions concerning the function and evolution of miT2SSs.

• Klíčová slova
• T2SS, evolution, mitochondria, mitochondrial evolution, protein secretion, protein transport, type II secretion system,
• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• bakteriální sekreční systémy metabolismus   MeSH
• gramnegativní bakterie metabolismus   MeSH
• periplazma metabolismus   MeSH
• sekreční systém typu II * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• bakteriální proteiny MeSH
• bakteriální sekreční systémy MeSH
• sekreční systém typu II * MeSH

Investigations of phytoplankton responses to iron stress in seawater are complicated by the fact that iron concentrations do not necessarily reflect bioavailability. Most studies to date have been based on single species or field samples and are problematic to interpret. Here, we report results from an experimental cocultivation model system that enabled us to evaluate interspecific competition as a function of iron content and form, and to study the effect of nutritional conditions on the proteomic profiles of individual species. Our study revealed that the dinoflagellate Amphidinium carterae was able to utilize iron from a hydroxamate siderophore, a strategy that could provide an ecological advantage in environments where siderophores present an important source of iron. Additionally, proteomic analysis allowed us to identify a potential candidate protein involved in iron acquisition from hydroxamate siderophores, a strategy that is largely unknown in eukaryotic phytoplankton.

• Klíčová slova
• (s)PLS-DA, (sparse) partial least squares discriminant analysis, AUC, area under curve, Amphidinium carterae, AtpE, ATP synthase, BCS, bathocuproinedisulfonic acid disodium salt, CREG1, cellular repressor of E1A stimulated genes 1, DFOB, desferrioxamine B, EDTA, ethylenediaminetetraacetic acid, ENT, enterobactin, FACS, fluorescence-activated cell sorting, FBAI, fructose-bisphosphate aldolase I, FBAII, fructose-bisphosphate aldolase II, FBP1, putative ferrichrome-binding protein, FOB, ferrioxamine B, Flow cytometry, ISIP, iron starvation induced protein, Iron, LHCX, light-harvesting complex subunits, LL, long-term iron limitation, LR, iron enrichment, Marine microalgae, NBD, nitrobenz-2-oxa-1,3-diazole, NPQ, nonphotochemical quenching, PAGE, polyacrylamide gel electrophoresis, PSI, photosystem I, PSII, photosystem II, PetA, cytochrome b6/f, Proteomics, PsaC, photosystem I iron-sulfur center, PsaD, photosystem I reaction center subunit II, PsaE, photosystem I reaction center subunit IV, PsaL, photosystem I reaction center subunit XI, PsbC, photosystem II CP43 reaction center protein, PsbV, cytochrome c-550, RR, long-term iron sufficiency, SOD1, superoxide dismutase [Cu-Zn], Siderophores,
• Publikační typ
• časopisecké články MeSH

Many of the currently available anti-parasitic and anti-fungal frontline drugs have severe limitations, including adverse side effects, complex administration, and increasing occurrence of resistance. The discovery and development of new therapeutic agents is a costly and lengthy process. Therefore, repurposing drugs with already established clinical application offers an attractive, fast-track approach for novel treatment options. In this study, we show that the anti-cancer drug candidate MitoTam, a mitochondria-targeted analog of tamoxifen, efficiently eliminates a wide range of evolutionarily distinct pathogens in vitro, including pathogenic fungi, Plasmodium falciparum, and several species of trypanosomatid parasites, causative agents of debilitating neglected tropical diseases. MitoTam treatment was also effective in vivo and significantly reduced parasitemia of two medically important parasites, Leishmania mexicana and Trypanosoma brucei, in their respective animal infection models. Functional analysis in the bloodstream form of T. brucei showed that MitoTam rapidly altered mitochondrial functions, particularly affecting cellular respiration, lowering ATP levels, and dissipating mitochondrial membrane potential. Our data suggest that the mode of action of MitoTam involves disruption of the inner mitochondrial membrane, leading to rapid organelle depolarization and cell death. Altogether, MitoTam is an excellent candidate drug against several important pathogens, for which there are no efficient therapies and for which drug development is not a priority.

• Klíčová slova
• Candida, Cryptococcus, Leishmania, Plasmodium, Trypanosoma, drug, mitochondria,
• MeSH
• antitumorózní látky * metabolismus   farmakologie   MeSH
• membránový potenciál mitochondrií MeSH
• Plasmodium falciparum MeSH
• přehodnocení terapeutických indikací léčivého přípravku MeSH
• Trypanosoma brucei brucei * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antitumorózní látky * MeSH

Although copper is an essential nutrient crucial for many biological processes, an excessive concentration can be toxic and lead to cell death. The metabolism of this two-faced metal must be strictly regulated at the cell level. In this study, we investigated copper homeostasis in two related unicellular organisms: nonpathogenic Naegleria gruberi and the "brain-eating amoeba" Naegleria fowleri. We identified and confirmed the function of their specific copper transporters securing the main pathway of copper acquisition. Adjusting to different environments with varying copper levels during the life cycle of these organisms requires various metabolic adaptations. Using comparative proteomic analyses, measuring oxygen consumption, and enzymatic determination of NADH dehydrogenase, we showed that both amoebas respond to copper deprivation by upregulating the components of the branched electron transport chain: the alternative oxidase and alternative NADH dehydrogenase. Interestingly, analysis of iron acquisition indicated that this system is copper-dependent in N. gruberi but not in its pathogenic relative. Importantly, we identified a potential key protein of copper metabolism of N. gruberi, the homolog of human DJ-1 protein, which is known to be linked to Parkinson's disease. Altogether, our study reveals the mechanisms underlying copper metabolism in the model amoeba N. gruberi and the fatal pathogen N. fowleri and highlights the differences between the two amoebas.

• Klíčová slova
• CTR copper transporters, DJ-1, Naegleria fowleri, Naegleria gruberi, alternative NADH dehydrogenase, alternative oxidase, copper, electron transport chain,
• Publikační typ
• časopisecké články MeSH

The type 2 secretion system (T2SS) is present in some Gram-negative eubacteria and used to secrete proteins across the outer membrane. Here we report that certain representative heteroloboseans, jakobids, malawimonads and hemimastigotes unexpectedly possess homologues of core T2SS components. We show that at least some of them are present in mitochondria, and their behaviour in biochemical assays is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). We additionally identified 23 protein families co-occurring with miT2SS in eukaryotes. Seven of these proteins could be directly linked to the core miT2SS by functional data and/or sequence features, whereas others may represent different parts of a broader functional pathway, possibly also involving the peroxisome. Its distribution in eukaryotes and phylogenetic evidence together indicate that the miT2SS-centred pathway is an ancestral eukaryotic trait. Our findings thus have direct implications for the functional properties of the early mitochondrion.

• MeSH
• biologické modely MeSH
• Eukaryota klasifikace   genetika   metabolismus   MeSH
• fylogeneze MeSH
• gramnegativní bakterie klasifikace   genetika   metabolismus   MeSH
• konzervovaná sekvence MeSH
• mitochondriální proteiny klasifikace   genetika   metabolismus   MeSH
• mitochondrie genetika   metabolismus   MeSH
• molekulární evoluce * MeSH
• molekulární modely MeSH
• Naegleria klasifikace   genetika   metabolismus   MeSH
• peroxizomy metabolismus   MeSH
• protozoální proteiny klasifikace   genetika   metabolismus   MeSH
• sekreční systém typu II klasifikace   genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• mitochondriální proteiny MeSH
• protozoální proteiny MeSH
• sekreční systém typu II MeSH

The productivity of the ocean is largely dependent on iron availability, and marine phytoplankton have evolved sophisticated mechanisms to cope with chronically low iron levels in vast regions of the open ocean. By analyzing the metabarcoding data generated from the Tara Oceans expedition, we determined how the global distribution of the model marine chlorarachniophyte Bigelowiella natans varies across regions with different iron concentrations. We performed a comprehensive proteomics analysis of the molecular mechanisms underpinning the adaptation of B. natans to iron scarcity and report on the temporal response of cells to iron enrichment. Our results highlight the role of phytotransferrin in iron homeostasis and indicate the involvement of CREG1 protein in the response to iron availability. Analysis of the Tara Oceans metagenomes and metatranscriptomes also points to a similar role for CREG1, which is found to be widely distributed among marine plankton but to show a strong bias in gene and transcript abundance toward iron-deficient regions. Our analyses allowed us to define a new subfamily of the CobW domain-containing COG0523 putative metal chaperones which are involved in iron metabolism and are restricted to only a few phytoplankton lineages in addition to B. natans At the physiological level, we elucidated the mechanisms allowing a fast recovery of PSII photochemistry after resupply of iron. Collectively, our study demonstrates that B. natans is well adapted to dynamically respond to a changing iron environment and suggests that CREG1 and COG0523 are important components of iron homeostasis in B. natans and other phytoplankton.IMPORTANCE Despite low iron availability in the ocean, marine phytoplankton require considerable amounts of iron for their growth and proliferation. While there is a constantly growing knowledge of iron uptake and its role in the cellular processes of the most abundant marine photosynthetic groups, there are still largely overlooked branches of the eukaryotic tree of life, such as the chlorarachniophytes. In the present work, we focused on the model chlorarachniophyte Bigelowiella natans, integrating physiological and proteomic analyses in culture conditions with the mining of omics data generated by the Tara Oceans expedition. We provide unique insight into the complex responses of B. natans to iron availability, including novel links to iron metabolism conserved in other phytoplankton lineages.

• Klíčová slova
• Bigelowiella natans, iron, metagenomics, metatranscriptomics, photosynthesis, phytoplankton, proteomics,
• Publikační typ
• časopisecké články MeSH

Copper is a trace metal that is necessary for all organisms but toxic when present in excess. Different mechanisms to avoid copper toxicity have been reported to date in pathogenic organisms such as Cryptococcus neoformans and Candida albicans. However, little if anything is known about pathogenic protozoans despite their importance in human and veterinary medicine. Naegleria fowleri is a free-living amoeba that occurs naturally in warm fresh water and can cause a rapid and deadly brain infection called primary amoebic meningoencephalitis (PAM). Here, we describe the mechanisms employed by N. fowleri to tolerate high copper concentrations, which include various strategies such as copper efflux mediated by a copper-translocating ATPase and upregulation of the expression of antioxidant enzymes and obscure hemerythrin-like and protoglobin-like proteins. The combination of different mechanisms efficiently protects the cell and ensures its high copper tolerance, which can be advantageous both in the natural environment and in the host. Nevertheless, we demonstrate that copper ionophores are potent antiamoebic agents; thus, copper metabolism may be considered a therapeutic target.

• Klíčová slova
• Copper, Copper-translocating ATPase, Hemerythrin, Ionophores, Naegleria fowleri, Oxidative stress,
• MeSH
• adenosintrifosfatasy metabolismus   MeSH
• Amoeba MeSH
• antioxidancia fyziologie   MeSH
• lidé MeSH
• měď metabolismus   MeSH
• mozek MeSH
• Naegleria fowleri * fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfatasy MeSH
• antioxidancia MeSH
• měď MeSH

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

BACKGROUND: Bacteria and mitochondria contain translocases that function to transport proteins across or insert proteins into their inner and outer membranes. Extant mitochondria retain some bacterial-derived translocases but have lost others. While BamA and YidC were integrated into general mitochondrial protein transport pathways (as Sam50 and Oxa1), the inner membrane TAT translocase, which uniquely transports folded proteins across the membrane, was retained sporadically across the eukaryote tree. RESULTS: We have identified mitochondrial TAT machinery in diverse eukaryotic lineages and define three different types of eukaryote-encoded TatABC-derived machineries (TatAC, TatBC and TatC-only). Here, we investigate TatAC and TatC-only machineries, which have not been studied previously. We show that mitochondria-encoded TatAC of the jakobid Andalucia godoyi represent the minimal functional pathway capable of substituting for the Escherichia coli TatABC complex and can transport at least one substrate. However, selected TatC-only machineries, from multiple eukaryotic lineages, were not capable of supporting the translocation of this substrate across the bacterial membrane. Despite the multiple losses of the TatC gene from the mitochondrial genome, the gene was never transferred to the cell nucleus. Although the major constraint preventing nuclear transfer of mitochondrial TatC is likely its high hydrophobicity, we show that in chloroplasts, such transfer of TatC was made possible due to modifications of the first transmembrane domain. CONCLUSIONS: At its origin, mitochondria inherited three inner membrane translocases Sec, TAT and Oxa1 (YidC) from its bacterial ancestor. Our work shows for the first time that mitochondrial TAT has likely retained its unique function of transporting folded proteins at least in those few eukaryotes with TatA and TatC subunits encoded in the mitochondrial genome. However, mitochondria, in contrast to chloroplasts, abandoned the machinery multiple times in evolution. The overall lower hydrophobicity of the Oxa1 protein was likely the main reason why this translocase was nearly universally retained in mitochondrial biogenesis pathways.

• Klíčová slova
• Hydrophobicity, Mitochondrial evolution, Protein transport, TAT translocase,
• MeSH
• Escherichia coli genetika   MeSH
• Eukaryota genetika   MeSH
• membránové transportní proteiny genetika   metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• molekulární evoluce * MeSH
• proteiny z Escherichia coli chemie   genetika   metabolismus   MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• membránové transportní proteiny MeSH
• proteiny z Escherichia coli MeSH