Search by property

This page provides a simple browsing interface for finding entities described by a property and a named value. Other available search interfaces include the page property search, and the ask query builder.

List of results

MitoCom2014 + (''MitoCom'' closing event and perspectives. Innsbruck, Austria; 2014 October 16)
Barsottini 2020 Commun Biol + (''Moniliophthora perniciosa'' is a fungal … ''Moniliophthora perniciosa'' is a fungal pathogen and causal agent of the witches' broom disease of cocoa, a threat to the chocolate industry and to the economic and social security in cocoa-planting countries. The membrane-bound enzyme alternative oxidase (MpAOX) is crucial for pathogen survival; however a lack of information on the biochemical properties of MpAOX hinders the development of novel fungicides. In this study, we purified and characterised recombinant MpAOX in dose-response assays with activators and inhibitors, followed by a kinetic characterization both in an aqueous environment and in physiologically-relevant proteoliposomes. We present structure-activity relationships of AOX inhibitors such as colletochlorin B and analogues which, aided by an MpAOX structural model, indicates key residues for protein-inhibitor interaction. We also discuss the importance of the correct hydrophobic environment for MpAOX enzymatic activity. We envisage that such results will guide the future development of AOX-targeting antifungal agents against ''M. perniciosa'', an important outcome for the chocolate industry.ortant outcome for the chocolate industry.)
Yurre 2020 Arq Bras Cardiol + (''Moringa oleifera'' seeds, which are used … ''Moringa oleifera'' seeds, which are used for water clarification, contain a lectin named WSMoL which has shown ''in vitro'' antibacterial and immunomodulatory activity. Due to their nutritional value and therapeutic potential, the leaves and seeds of this tree are eaten in some communities. Some plant lectins are non-toxic to mammals, but others have been reported to be harmful when ingested or administered by other means. As one of the steps needed to define the safety of WSMoL, we evaluated possible cardiotoxic effects of this purified protein. WSMoL was administered for 21 consecutive days to mice by gavage. Electrophysiological, mechanical, and metabolic cardiac functions were investigated by ''in vivo'' and ''ex vivo'' electrocardiographic recordings, nuclear magnetic resonance, and high-resolution respirometry. The treatment with WSMoL did not induce changes in blood glucose levels or body weight in comparison with control group. Moreover, the heart weight/body weight and heart weight/tibia length ratios were similar in both groups. Lectin ingestion also did not modify glucose tolerance or insulin resistance. No alterations were observed in electrocardiographic parameters or cardiac action potential duration. The heart of mice from the control and WSMoL groups showed preserved left ventricular function. Furthermore, WSMoL did not induce changes in mitochondrial function (in all cases, p > 0.05). The administration of WSMoL demonstrated a cardiac safety profile. These results contribute to the safety evaluation of using ''M. oleifera'' seeds to treat water, since this lectin is present in the preparation employed by some populations to this end.ion employed by some populations to this end.)
Pelaez Coyotl 2020 Pharmaceutics + (''Mycobacterium tuberculosis'' (MTB) is th … ''Mycobacterium tuberculosis'' (MTB) is the principal cause of human tuberculosis (TB), which is a serious health problem worldwide. The development of innovative therapeutic modalities to treat TB is mainly due to the emergence of multi drug resistant (MDR) TB. Autophagy is a cell-host defense process. Previous studies have reported that autophagy-activating agents eliminate intracellular MDR MTB. Thus, combining a direct antibiotic activity against circulating bacteria with autophagy activation to eliminate bacteria residing inside cells could treat MDR TB. We show that the synthetic peptide, IP-1 (KFLNRFWHWLQLKPGQPMY), induced autophagy in HEK293T cells and macrophages at a low dose (10 μM), while increasing the dose (50 μM) induced cell death; IP-1 induced the secretion of TNFα in macrophages and killed Mtb at a dose where macrophages are not killed by IP-1. Moreover, IP-1 showed significant therapeutic activity in a mice model of progressive pulmonary TB. In terms of the mechanism of action, IP-1 sequesters ATP ''in vitro'' and inside living cells. Thus, IP-1 is the first antimicrobial peptide that eliminates MDR MTB infection by combining four activities: reducing ATP levels, bactericidal activity, autophagy activation, and TNFα secretion. autophagy activation, and TNFα secretion.)
Iqbal 2018 Pathogens + (''Mycobacterium tuberculosis'' (Mtb) exhib … ''Mycobacterium tuberculosis'' (Mtb) exhibits remarkable metabolic flexibility that enables it to survive a plethora of host environments during its life cycle. With the advent of bedaquiline for treatment of multidrug-resistant tuberculosis, oxidative phosphorylation has been validated as an important target and a vulnerable component of mycobacterial metabolism. Exploiting the dependence of Mtb on oxidative phosphorylation for energy production, several components of this pathway have been targeted for the development of new antimycobacterial agents. This includes targeting NADH dehydrogenase by phenothiazine derivatives, menaquinone biosynthesis by DG70 and other compounds, terminal oxidase by imidazopyridine amides and ATP synthase by diarylquinolines. Importantly, oxidative phosphorylation also plays a critical role in the survival of persisters. Thus, inhibitors of oxidative phosphorylation can synergize with frontline TB drugs to shorten the course of treatment. In this review, we discuss the oxidative phosphorylation pathway and development of its inhibitors in detail.d development of its inhibitors in detail.)
Franco 2020 bioRxiv + (''Mycobacterium tuberculosis'' (Mtb) regul … ''Mycobacterium tuberculosis'' (Mtb) regulates the macrophage metabolic state to thrive in the host. Yet, the responsible mechanisms remain elusive. Macrophage activation towards the microbicidal (M1) program depends on the HIF-1 α-mediated metabolic shift from oxidative phosphorylation towards glycolysis. Here, we asked whether a tuberculosis (TB) microenvironment changes the M1 macrophage metabolic state. We exposed M1 macrophages to the acellular fraction of tuberculous pleural effusions (TB-PE), and found lower glycolytic activity, accompanied by elevated levels of oxidative phosphorylation and bacillary load, compared to controls. The host-derived lipid fraction of TB-PE drove these metabolic alterations. HIF-1α stabilization reverted the effect of TB-PE by restoring M1 metabolism. As a proof-of-concept, Mtb-infected mice with stabilized HIF-1α displayed lower bacillary loads and a pronounced M1-like metabolic profile in alveolar macrophages. Collectively, we demonstrate that host-derived lipids from a TB-associated microenvironment alter the M1 macrophage metabolic reprogramming by hampering HIF-1α functions, thereby impairing control of Mtb infection.hereby impairing control of Mtb infection.)
Baines 2020 Biochim Biophys Acta Bioenerg + (''No abstract available'')
Coen 2013 Obesity (Silver Spring) + (''OBJECTIVE'': The link between a reduced … ''OBJECTIVE'': The link between a reduced capacity for skeletal muscle mitochondrial fatty acid oxidation (FAO) and lipotoxicity in human insulin resistance has been the subject of intense debate. The objective of this study was to investigate whether reduced FAO is associated with elevated acyl CoA, ceramide, and diacylglycerol (DAG) in severely obese insulin resistant subjects.''DESIGN AND METHODS'': Muscle biopsies were conducted in lean (L, 22.6 ± 0.5 kg/m2, ''n'' = 8), Class I (CI, 32.1 ± 0.4 kg/m2, ''n'' = 7) and Class II&III obese (CII&III, 45.6 ± 1.1 kg/m2, ''n'' = 15) women for acyl CoA, sphingolipid and DAG profiling. Intramyocellular triglyceride (IMTG) content was determined by histology. FAO was assessed by incubating muscle homogenates with [1-C]palmitate and measuring CO2 production. Cardiolipin content was quantified as an index of mitochondrial content. Lipid metabolism proteins, DGAT1, PLIN5, and PNPLA2 were quantified in biopsy samples by western blot.''RESULTS'': CII&III were more insulin resistant (HOMA-IR: 4.5 ± 0.5 vs. 1.1 ± 0.1, ''P'' < 0.001), and had lower FAO (∼58%, ''P'' = 0.007) and cardiolipin content (∼31%, ''P'' = 0.013) compared to L. IMTG was elevated in CI (''P'' = 0.04) and CII&III (''P'' = 0.04) compared to L. Sphingolipid content was higher in CII&III compared to L (13.6 ± 1.1 vs. 10.3 ± 0.5 pmol/mg, ''P'' = 0.031) whereas DAG content was not different among groups. DGAT1 was elevated in CII&III, and PLIN5 was elevated in CI compared to L.''CONCLUSION'': Severe obesity is associated with reduced muscle oxidative capacity and occurs concomitantly with elevated IMTG, ceramide and insulin resistance.rs concomitantly with elevated IMTG, ceramide and insulin resistance.)
Ceusters 2012 Am J Vet Res + (''Objective'' To culture equine myoblasts … ''Objective'' To culture equine myoblasts from muscle microbiopsy specimens, examine myoblast production of reactive oxygen species (ROS) in conditions of anoxia followed by reoxygenation, and assess the effects of horseradish peroxidase (HRP) and myeloperoxidase (MPO) on ROS production.''Animals'' 5 healthy horses (5 to 15 years old).''Procedures'' Equine skeletal myoblast cultures were derived from 1 or 2 microbiopsy specimens obtained from a triceps brachii muscle of each horse. Cultured myoblasts were exposed to conditions of anoxia followed by reoxygenation or to conditions of normoxia (control cells). Cell production of ROS in the presence or absence of HRP or MPO was assessed by use of a gas chromatography method, after which cells were treated with a 3,3′-diaminobenzidine chromogen solution to detect peroxidase binding.''Results'' Equine skeletal myoblasts were successfully cultured from microbiopsy specimens. In response to anoxia and reoxygenation, ROS production of myoblasts increased by 71%, compared with that of control cells. When experiments were performed in the presence of HRP or MPO, ROS production in myoblasts exposed to anoxia and reoxygenation was increased by 228% and 183%, respectively, compared with findings for control cells. Chromogen reaction revealed a close adherence of peroxidases to cells, even after several washes.''Conclusions and Clinical Relevance'' Results indicated that equine skeletal myoblast cultures can be generated from muscle microbiopsy specimens. Anoxia-reoxygenationtreated myoblasts produced ROS, and production was enhanced in the presence of peroxidases. This experimental model could be used to study the damaging effect of exercise on muscles in athletic horses.of exercise on muscles in athletic horses.)
Fecker 2020 Biomolecules + (''Oenothera biennis'' L. (OB), also common … ''Oenothera biennis'' L. (OB), also commonly known as evening primrose, belongs to the Onagraceae family and has the best studied biological activity of all the members in the family. In therapy, the most frequently used type of extracts are from the aerial part, which are the fatty oils obtained from the seeds and have a wide range of medicinal properties. The aim of this study was to evaluate the phytochemical composition and biological activity of OB hydroalcoholic extract and to provide directions for the antimicrobial effect, antiproliferative and pro-apoptotic potential against A375 melanoma cell line, and anti-angiogenic and anti-inflammatory capacity. The main polyphenols and flavonoids identified were gallic acid, caffeic acid, epicatechin, coumaric acid, ferulic acid, rutin and rosmarinic acid. The total phenolic content was 631.496 µgGAE/mL of extract and the antioxidant activity was 7258.67 μmolTrolox/g of extract. The tested extract had a mild bacteriostatic effect on the tested bacterial strains. It was bactericidal only against ''Candida spp.'' and ''S. aureus''. In the set of experimental conditions, the OB extract only manifested significant antiproliferative and pro-apoptotic activity against the A375 human melanoma cell line at the highest tested concentration, namely 60 μg/mL. The migration potential of A375 cells was hampered by the OB extract in a concentration-dependent manner. Furthermore, at the highest tested concentration, the OB extract altered the mitochondrial function ''in vitro'', while reducing the angiogenic reaction, hindering compact tumor formation in the chorioallantoic membrane assay. Moreover, the OB extract elicited an anti-inflammatory effect on the experimental animal model of ear inflammation.rimental animal model of ear inflammation.)

(''Oenothera biennis'' L. (OB), also commonly known as evening primrose,)

Verma 2023 Int J Mol Sci + (''Porphyromonas gingivalis'' (''P. gingiva … ''Porphyromonas gingivalis'' (''P. gingivalis''), a key pathogen in periodontitis, is associated with neuroinflammation. Periodontal disease increases with age; 70.1% of adults 65 years and older have periodontal problems. However, the ''P. gingivalis''- lipopolysaccharide (LPS)induced mitochondrial dysfunction in neurodegenerative diseases remains elusive. In this study, we investigated the possible role of ''P. gingivalis''-LPS in mitochondrial dysfunction during neurodegeneration. We found that ''P. gingivalis''-LPS treatment activated toll-like receptor (TLR) 4 signaling and upregulated the expression of Alzheimer's disease-related dementia and neuroinflammatory markers. Furthermore, the LPS treatment significantly exacerbated the production of reactive oxygen species and reduced the mitochondrial membrane potential. Our study highlighted the pivotal role of ''P. gingivalis''-LPS in the repression of serum response factor (SRF) and its co-factor p49/STRAP that regulate the actin cytoskeleton. The LPS treatment repressed the genes involved in mitochondrial function and biogenesis. ''P. gingivalis''-LPS negatively altered oxidative phosphorylation and glycolysis and reduced total adenosine triphosphate (ATP) production. Additionally, it specifically altered the mitochondrial functions in complexes I, II, and IV of the mitochondrial electron transport chain. Thus, it is conceivable that ''P. gingivalis''-LPS causes mitochondrial dysfunction through oxidative stress and inflammatory events in neurodegenerative diseases.tory events in neurodegenerative diseases.)
Lee 2012 Invest Ophthalmol Vis Sci + (''Purpose'': Following the recent demonstr … ''Purpose'': Following the recent demonstration of increased mitochondrial DNA mutations in lymphocytes of POAG patients, the authors sought to characterize mitochondrial function in a separate cohort of POAG.''Methods'': Using similar methodology to that previous applied to Leber's hereditary optic neuropathy (LHON) patients, maximal adenosine triphosphate (ATP) synthesis and cellular respiration rates, as well as cell growth rates in glucose and galactose media, were assessed in transformed lymphocytes from POAG patients (n = 15) and a group of age- and sex-matched controls (n = 15).''Results'': POAG lymphoblasts had significantly lower rates of complex-I-driven ATP synthesis, with preserved complex-II-driven ATP synthesis. Complex-I driven maximal respiration was also significantly decreased in patient cells. Growth in galactose media, where cells are forced to rely on mitochondrial ATP production, revealed no significant differences between the control and POAG cohort.''Conclusions'': POAG lymphoblasts in the study cohort exhibited a defect in complex-I of the oxidative phosphorylation pathway, leading to decreased rates of respiration and ATP production. Studies in LHON and other diseases have established that lymphocyte oxidative phosphorylation measurement is a reliable indicator of systemic dysfunction of this pathway. While these defects did not impact lymphoblast growth when the cells were forced to rely on oxidative ATP supply, the authors suggest that in the presence of a multitude of cellular stressors as seen in the early stages of POAG, these defects may lead to a bioenergetic crisis in retinal ganglion cells and an increased susceptibility to cell death.an increased susceptibility to cell death.)
Li 2018 Gene + (''SURF1'' is an assembly factor of mitocho … ''SURF1'' is an assembly factor of mitochondrial complex IV, and its mutations are the primary cause of Leigh syndrome in infants. To date, over 100 ''SURF1'' mutations have been reported worldwide, but the spectrum of the ''SURF1'' mutations in China remains unclear. Here, using next-generation sequencing targeting mitochondrial protein-coding sequences, we sequenced 178 patients suspected to have mitochondrial diseases. Fifteen ''SURF1'' mutations were identified in 12 Leigh syndrome patients, of which three, c.465_466delAA, c.532A > T, and c.826_827ins AGCATCTGCAGTACATCG, were newly described. The percentage of ''SURF1'' frameshift mutations (6/28, 21.4%) we detected in Chinese population is higher than other studies (21/106, 19.8%) with different populations, however, the percentage of missense mutations is lower in this study than others (4/28, 14.3% VS. 25/106, 23.6%). Since complex IV can be detected in cells carrying missense mutations (3/8) but not in cells carrying null mutations (0/4) by using cell model-based complementation assay, our results indicate that ''SURF1'' mutations may be associated with worse clinical outcome in Chinese patients than other populations. However, studies with larger sample size are needed to verify this conclusion. Additionally, we found that the frameshift mutations resulting in protein truncation closer to the C-terminus are not associated with better disease prognosis. Lastly, we found that determining the levels of complex IV assembly using cell models or lymphocyte analysis rather than invasive muscle and skin fibroblast biopsy, may help predict disease progression in Leigh syndrome patients.sease progression in Leigh syndrome patients.)
Rosenfeld 2003 Yeast + (''Saccharomyces cerevisiae'' is a facultat … ''Saccharomyces cerevisiae'' is a facultative anaerobe devoid of mitochondrial alternative oxidase. In this yeast, the structure and biogenesis of the respiratory chain, on the one hand, and the functional interactions of oxidative phosphorylation with the cellular energetic metabolism, on the other, are well documented. However, to our knowledge, the molecular aspects and the physiological roles of the non-respiratory pathways that utilize molecular oxygen have not yet been reviewed. In this paper, we review the various non-respiratory pathways in a global context of utilization of molecular oxygen in S. cerevisiae. The roles of these pathways are examined as a function of environmental conditions, using either physiological, biochemical or molecular data. Special attention is paid to the characterization of the so-called 'cyanide-resistant respiration' that is induced by respiratory deficiency, catabolic repression and oxygen limitation during growth. Finally, several aspects of oxygen sensing are discussed.l aspects of oxygen sensing are discussed.)
Oliveira 2016 PLOS ONE + (''Schistosoma mansoni'', one of the causat … ''Schistosoma mansoni'', one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along ''S. mansoni'' development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by ''S. mansoni'' metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult ''S. mansoni'' worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult ''S. mansoni'' worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute to redox biology among parasite sexes.ute to redox biology among parasite sexes.)
Konickova 2014 Annals Hepatol + (''Spirulina platensis'' is a blue-green al … ''Spirulina platensis'' is a blue-green alga used as a dietary supplement because of its hypocholesterolemic properties. Among other bioactive substances, it is also rich in tetrapyrrolic compounds closely related to bilirubin molecule, a potent antioxidant and anti-proliferative agent. The aim of our study was to evaluate possible anticancer effects of ''S. platensis'' and ''S. platensis''-derived tetrapyrroles using an experimental model of pancreatic cancer. The anti-proliferative effects of ''S. platensis'' and its tetrapyrrolic components [phycocyanobilin (PCB) and chlorophyllin, a surrogate molecule for chlorophyll A] were tested on several human pancreatic cancer cell lines and xenotransplanted nude mice. The effects of experimental therapeutics on mitochondrial reactive oxygen species (ROS) production and glutathione redox status were also evaluated. Compared to untreated cells, experimental therapeutics significantly decreased proliferation of human pancreatic cancer cell lines ''in vitro'' in a dose-dependent manner (from 0.16 g•L-1 [''S. platensis''], 60 μM [PCB], and 125 μM [chlorophyllin], ''p''<0.05). The anti-proliferative effects of ''S. platensis'' were also shown ''in vivo'', where inhibition of pancreatic cancer growth was evidenced since the third day of treatment (''p''<0.05). All tested compounds decreased generation of mitochondrial ROS and glutathione redox status (''p''=0.0006; 0.016; and 0.006 for ''S. platensis'', PCB, and chlorophyllin, respectively). In conclusion, ''S. platensis'' and its tetrapyrrolic components substantially decreased the proliferation of experimental pancreatic cancer. These data support a chemopreventive role of this edible alga. Furthermore, it seems that dietary supplementation with this alga might enhance systemic pool of tetrapyrroles, known to be higher in subjects with Gilbert syndrome.roles, known to be higher in subjects with Gilbert syndrome.)
Uribe-Alvarez 2016 Abstract MitoFit Science Camp 2016 + (''Staphylcoccus epidermidis'' does not inv … ''Staphylcoccus epidermidis'' does not invade healthy tissues, however, it has been identified as a cause of nosocomial infections due to its ability to form biofilms on polymer surfaces [1]. ''S. epidermidis'' can be grown at different oxygen concentrations ([O2]), including mammalian skin where [O2] ranges from 3-5% and in anaerobic altered tissues [2,3]. Biofilm formation of ''S. epidermidis'' and its respiratory chain components grown in aerobic, microaerobic and anaerobic conditions were evaluated by in-gel activities, enzymatic activities, spectrophotometry and oxymetry. Varying [O2] modified both biofilm formation and the components in the respiratory chain: At high [O2], little tendency to form biofilms was observed. ''S. epidermidis'' expressed glycerol-3-phosphate, pyruvate, ethanol and succinate dehydrogenases; and cyt bo and aa3. Under micro-aerobiosis, biofilm formation increased slightly; pyruvate, ethanol, glycerol-3-phosphate and succinate dehydrogenase decreased; aa3 cyt was not detected; Under anaerobiosis high biofilm-formation and low ethanol and pyruvate dehydrogenase activities were found; anaerobic nitrate dehydrogenase activity was detected. Aerobic-grown cells with cyanide increased biofilm formation. Anaerobic-grown cells with methylamine decreased biofilm formation. Thus, either a decrease in [O2] or the inhibition of the aerobic chain led ''S. epidermidis'' to associate into biofilms. In contrast, high [O2] or inhibition of the anaerobic nitrate reductase prevented biofilm formation suggesting that the enzymes expressed at low to null [O2] are therapeutic targets against biofilm formation by ''S. epidermidis''. expressed at low to null [O2] are therapeutic targets against biofilm formation by ''S. epidermidis''.)
Snow 2015 PLoS One + (''Trichodesmium'' is a biogeochemically im … ''Trichodesmium'' is a biogeochemically important marine cyanobacterium, responsible for a significant proportion of the annual 'new' nitrogen introduced into the global ocean. These non-heterocystous filamentous diazotrophs employ a potentially unique strategy of near-concurrent nitrogen fixation and oxygenic photosynthesis, potentially burdening Trichodesmium with a particularly high iron requirement due to the iron-binding proteins involved in these processes. Iron availability may therefore have a significant influence on the biogeography of Trichodesmium. Previous investigations of molecular responses to iron stress in this keystone marine microbe have largely been targeted. Here a holistic approach was taken using a label-free quantitative proteomics technique (MSE) to reveal a sophisticated multi-faceted proteomic response of Trichodesmium erythraeum IMS101 to iron stress. Increased abundances of proteins known to be involved in acclimation to iron stress and proteins known or predicted to be involved in iron uptake were observed, alongside decreases in the abundances of iron-binding proteins involved in photosynthesis and nitrogen fixation. Preferential loss of proteins with a high iron content contributed to overall reductions of 55-60% in estimated proteomic iron requirements. Changes in the abundances of iron-binding proteins also suggested the potential importance of alternate photosynthetic pathways as Trichodesmium reallocates the limiting resource under iron stress. ''Trichodesmium'' therefore displays a significant and integrated proteomic response to iron availability that likely contributes to the ecological success of this species in the ocean.ical success of this species in the ocean.)
Subrtova 2013 Abstract MiP2013 + (''Trypanosoma brucei'' is a parasitic flag … ''Trypanosoma brucei'' is a parasitic flagellate that causes devastating diseases of humans and lifestock. The infective form dwells in the glucose rich environment of mammalian blood and generate energy solely via glycolysis. In consequence, the bloodstream stage single mitochondrion is highly reduced lacking key Krebs cycle enzymes and traditional cytochrome mediated respiratory chain. Interestingly, the essential mitochondrial membrane potential (Δ''ψ''mt) is maintained by hydrolytic activity of the unique FoF1-ATPase, which contains several trypanosoma specific subunits of unknown function [1].We determined that one of the largest novel subunit, Tb2930 (43 kDa), is membrane-bound and localizes into monomeric and multimeric assemblies of the FoF1-ATPase. RNAi silencing of Tb2930 led to a significant decrease of Δ''ψ''mt and consequently to ''T. brucei'' growth inhibition, indicating that the FoF1-ATPase is not functioning properly even though its structural intergrity seems to be almost unchanged. To further explore the function of this protein, we employed naturally occuring trypanosoma strain that lacks mtDNA (dyskinetoplastic, Dk) including subunit a, an essential component of the Fo-moiety and proton pore. These Dk cells maintain Δ''ψ''mt by electrogenic exchange of ATP4-/ADP3- by the ATP/ADP carrier (AAC) and hydrolytic activity of the soluble F1-ATPase [2]. So far, it has been assumed that only the F1-moiety subunits are present and will be essential for these parasites. Interestingly, glycerol gradient sedimentation and native electrophoresis of Dk mitochondria revealed the presence of high molecular weight ATPase complexes that correspond to the bloodstream stage monomeric and multimeric FoF1-ATPase. Furthermore, the Tb2930 subunit is expressed in Dk cells and co-sediments with these high molecular weight membrane bound complexes. The RNAi study demonstrated that Tb2930 subunit is essential for Dk trypanosoma cells and crucial for maintaining Δ''ψ''mt. Importantly, upon ablation of Tb2930 we observed a shift of the FoF1-ATPase complexes to the lower S-values on glycerol gradient, where the free F1-ATPase sediments, indicating changes in the structural integrity of the Dk FoF1-ATPase. In conclusion, we propose that Tb2930 is responsible for connecting the Dk F1-ATPase to the mitochondrial membrane in the absence of subunit a of the Fo-moiety, thus increasing the efficiency of the functional association between F1-ATPase and AAC.y, thus increasing the efficiency of the functional association between F1-ATPase and AAC.)
Dolezelova 2017 Abstract IOC122 + (''Trypanosoma brucei'' undergoes a complex … ''Trypanosoma brucei'' undergoes a complex life cycle as it alternates between a mammalian host and the blood-feeding insect vector, a tsetse fly. Due to the different environments, the distinct life stages differ in their energy metabolism, i.e. insect stage (procyclic cells, PS) depends on mitochondrial oxidative phosphorylation (OXPHOS) for ATP production while the bloodstream stage (BS) gains energy by aerobic glycolysis. The dramatic switch from the OXPHOS to glycolysis happens during the complex development of the PS in the tsetse fly. This development differentiation is characterized by extensive remodeling of mitochondrion structure and changes in mitochondrial bioenergetics. Importantly, the molecular mechanism behind this process is completely unknown. We have established the ''in vitro'' differentiation system, in which the transition from PS to epimastigotes followed by differentiation to transmission-ready metacylic trypanosomes is triggered by RNA binding protein 6 (RBP6) expression. This ''in vitro'' induced differentiation of PF cells takes 8 days. The appearance of epimastigotes and metacyclic trypanosomes in the culture was mapped using light and fluorescent microscopy. The whole cell proteome of cell culture harvested every day after the RBP6 induction was identified by label-free quantitative mass spectrometry. This proteomic data serves as a resource for further detailed characterization of changes happening in the parasite mitochondrion as well as identification of possible candidates involved in the PS differentiation.idates involved in the PS differentiation.)