Euglenids have long been studied due to their unique physiology and versatile metabolism, providing underpinnings for much of our understanding of photosynthesis and biochemistry, and a growing opportunity in biotechnology. Until recently there has been a lack of genetic studies due to their large and complex genomes, but recently new technologies have begun to unveil their genetic capabilities. Whilst much research has focused on the model organism Euglena gracilis, other members of the euglenids have now started to receive due attention. Currently only poor nuclear genome assemblies of E. gracilis and Rhabdomonas costata are available, but there are many more plastid genome sequences and an increasing number of transcriptomes. As more assemblies become available, there are great opportunities to understand the fundamental biology of these organisms and to exploit them for biotechnology.
Euglena gracilis is a freshwater flagellate possessing secondary chloroplast of green algal origin. This protist has numerous biotechnological applications such as production of biofuels and pharmaceuticals, and it can be also used for bioremediation of polluted water and wastewater. One of the highest limitations for its large-scale cultivation is that it cannot synthesize vitamins B1 and B12 which are expensive and they have to be added to media. This study revealed that E. gracilis can be grown for long time periods without the addition of vitamins B1 and B12 in the co-culture containing filamentous fungus Cladosporium westerdijkiae, and bacteria Lysinibacillus boronitolerans and Pseudobacillus badius. Growing of E. gracilis in such co-cultures without the addition of vitamins can dramatically reduce large scale cultivation costs. Moreover, C. westerdijkiae could be used in biotechnology for immobilization and effective harvesting of E. gracilis from big cultivation containers by bioflocculation.
- MeSH
- Bacillaceae MeSH
- Bacillus MeSH
- Cladosporium MeSH
- Euglena gracilis * MeSH
- thiamin MeSH
- vitaminy MeSH
- Publikační typ
- časopisecké články MeSH
Most secondary nonphotosynthetic eukaryotes have retained residual plastids whose physiological role is often still unknown. One such example is Euglena longa, a close nonphotosynthetic relative of Euglena gracilis harboring a plastid organelle of enigmatic function. By mining transcriptome data from E. longa, we finally provide an overview of metabolic processes localized to its elusive plastid. The organelle plays no role in the biosynthesis of isoprenoid precursors and fatty acids and has a very limited repertoire of pathways concerning nitrogen-containing metabolites. In contrast, the synthesis of phospholipids and glycolipids has been preserved, curiously with the last step of sulfoquinovosyldiacylglycerol synthesis being catalyzed by the SqdX form of an enzyme so far known only from bacteria. Notably, we show that the E. longa plastid synthesizes tocopherols and a phylloquinone derivative, the first such report for nonphotosynthetic plastids studied so far. The most striking attribute of the organelle could be the presence of a linearized Calvin-Benson (CB) pathway, including RuBisCO yet lacking the gluconeogenetic part of the standard cycle, together with ferredoxin-NADP+ reductase (FNR) and the ferredoxin/thioredoxin system. We hypothesize that the ferredoxin/thioredoxin system activates the linear CB pathway in response to the redox status of the E. longa cell and speculate on the role of the pathway in keeping the redox balance of the cell. Altogether, the E. longa plastid defines a new class of relic plastids that is drastically different from the best-studied organelle of this category, the apicoplast.IMPORTANCE Colorless plastids incapable of photosynthesis evolved in many plant and algal groups, but what functions they perform is still unknown in many cases. Here, we study the elusive plastid of Euglena longa, a nonphotosynthetic cousin of the familiar green flagellate Euglena gracilis We document an unprecedented combination of metabolic functions that the E. longa plastid exhibits in comparison with previously characterized nonphotosynthetic plastids. For example, and truly surprisingly, it has retained the synthesis of tocopherols (vitamin E) and a phylloquinone (vitamin K) derivative. In addition, we offer a possible solution of the long-standing conundrum of the presence of the CO2-fixing enzyme RuBisCO in E. longa Our work provides a detailed account on a unique variant of relic plastids, the first among nonphotosynthetic plastids that evolved by secondary endosymbiosis from a green algal ancestor, and suggests that it has persisted for reasons not previously considered in relation to nonphotosynthetic plastids.
Euglena gracilis is a metabolically flexible, photosynthetic, and adaptable free-living protist of considerable environmental importance and biotechnological value. By label-free liquid chromatography tandem mass spectrometry, a total of 1,786 proteins were identified from the E. gracilis purified mitochondria, representing one of the largest mitochondrial proteomes so far described. Despite this apparent complexity, protein machinery responsible for the extensive RNA editing, splicing, and processing in the sister clades diplonemids and kinetoplastids is absent. This strongly suggests that the complex mechanisms of mitochondrial gene expression in diplonemids and kinetoplastids occurred late in euglenozoan evolution, arising independently. By contrast, the alternative oxidase pathway and numerous ribosomal subunits presumed to be specific for parasitic trypanosomes are present in E. gracilis. We investigated the evolution of unexplored protein families, including import complexes, cristae formation proteins, and translation termination factors, as well as canonical and unique metabolic pathways. We additionally compare this mitoproteome with the transcriptome of Eutreptiella gymnastica, illuminating conserved features of Euglenida mitochondria as well as those exclusive to E. gracilis. This is the first mitochondrial proteome of a free-living protist from the Excavata and one of few available for protists as a whole. This study alters our views of the evolution of the mitochondrion and indicates early emergence of complexity within euglenozoan mitochondria, independent of parasitism.
Trypanosoma brucei is an important human pathogen. In this study, we have focused on the characterization of FtsH protease, ATP-dependent membrane-bound mitochondrial enzyme important for regulation of protein abundance. We have determined localization and orientation of all six putative T.brucei FtsH homologs in the inner mitochondrial membrane by in silico analyses, by immunofluorescence, and with protease assay. The evolutionary origin of these homologs has been tested by comparative phylogenetic analysis. Surprisingly, some kinetoplastid FtsH proteins display inverted orientation in the mitochondrial membrane compared to related proteins of other examined eukaryotes. Moreover, our data strongly suggest that during evolution the orientation of FtsH protease in T. brucei varied due to both loss and acquisition of the transmembrane domain.
- MeSH
- Arabidopsis klasifikace enzymologie genetika MeSH
- Euglena gracilis klasifikace enzymologie genetika MeSH
- Euglena longa klasifikace enzymologie genetika MeSH
- exprese genu MeSH
- fylogeneze MeSH
- izoenzymy chemie genetika metabolismus MeSH
- konzervovaná sekvence MeSH
- Leishmania major klasifikace enzymologie genetika MeSH
- lidé MeSH
- mitochondriální membrány chemie enzymologie MeSH
- mitochondriální proteiny chemie genetika metabolismus MeSH
- mitochondrie enzymologie genetika MeSH
- molekulární evoluce * MeSH
- myši MeSH
- proteasy chemie genetika metabolismus MeSH
- proteinové domény MeSH
- protozoální proteiny chemie genetika metabolismus MeSH
- Saccharomyces cerevisiae klasifikace enzymologie genetika MeSH
- Trypanosoma brucei brucei klasifikace enzymologie genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Photosynthetic euglenids are major contributors to fresh water ecosystems. Euglena gracilis in particular has noted metabolic flexibility, reflected by an ability to thrive in a range of harsh environments. E. gracilis has been a popular model organism and of considerable biotechnological interest, but the absence of a gene catalogue has hampered both basic research and translational efforts. RESULTS: We report a detailed transcriptome and partial genome for E. gracilis Z1. The nuclear genome is estimated to be around 500 Mb in size, and the transcriptome encodes over 36,000 proteins and the genome possesses less than 1% coding sequence. Annotation of coding sequences indicates a highly sophisticated endomembrane system, RNA processing mechanisms and nuclear genome contributions from several photosynthetic lineages. Multiple gene families, including likely signal transduction components, have been massively expanded. Alterations in protein abundance are controlled post-transcriptionally between light and dark conditions, surprisingly similar to trypanosomatids. CONCLUSIONS: Our data provide evidence that a range of photosynthetic eukaryotes contributed to the Euglena nuclear genome, evidence in support of the 'shopping bag' hypothesis for plastid acquisition. We also suggest that euglenids possess unique regulatory mechanisms for achieving extreme adaptability, through mechanisms of paralog expansion and gene acquisition.
Euglenophytes are a familiar algal group with green alga-derived secondary plastids, but the knowledge of euglenophyte plastid function and evolution is still highly incomplete. With this in mind we sequenced and analysed the transcriptome of the non-photosynthetic species Euglena longa. The transcriptomic data confirmed the absence of genes for the photosynthetic machinery, but provided candidate plastid-localised proteins bearing N-terminal bipartite topogenic signals (BTSs) of the characteristic euglenophyte type. Further comparative analyses including transcriptome assemblies available for photosynthetic euglenophytes enabled us to unveil salient aspects of the basic euglenophyte plastid infrastructure, such as plastidial targeting of several proteins as C-terminal translational fusions with other BTS-bearing proteins or replacement of the conventional eubacteria-derived plastidial ribosomal protein L24 by homologs of archaeo-eukaryotic origin. Strikingly, no homologs of any key component of the TOC/TIC system and the plastid division apparatus are discernible in euglenophytes, and the machinery for intraplastidial protein targeting has been simplified by the loss of the cpSRP/cpFtsY system and the SEC2 translocon. Lastly, euglenophytes proved to encode a plastid-targeted homolog of the termination factor Rho horizontally acquired from a Lambdaproteobacteria-related donor. Our study thus further documents a substantial remodelling of the euglenophyte plastid compared to its green algal progenitor.
- MeSH
- Euglena longa klasifikace cytologie genetika MeSH
- fotosyntéza * MeSH
- fylogeneze MeSH
- molekulární evoluce * MeSH
- plastidy genetika MeSH
- proteiny chloroplastové genetika MeSH
- sekvence nukleotidů MeSH
- sekvenční homologie MeSH
- stanovení celkové genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any.
Euglenoid flagellates are mainly fresh water protists growing in highly diverse environments making them well-suited for a multiplicity of biotechnology applications. Phototrophic euglenids possesses complex chloroplasts of green algal origin bounded by three membranes. Euglena nuclear and plastid genome organization, gene structure and gene expression are distinctly different from other organisms. Our observations on the model organism Euglena gracilis indicate that transcription of both the plastid and nuclear genome is insensitive to environmental changes and that gene expression is regulated mainly at the post-transcriptional level. Euglena plastids have been proposed as a site for the production of proteins and value added metabolites of biotechnological interest. Euglena has been shown to be a suitable protist species to be used for production of several compounds that are used in the production of cosmeceuticals and nutraceuticals, such as α-tocopherol, wax esters, polyunsaturated fatty acids, biotin and tyrosine. The storage polysaccharide, paramylon, has immunostimulatory properties and has shown a promise for biomaterials production. Euglena biomass can be used as a nutritional supplement in aquaculture and in animal feed. Diverse applications of Euglena in environmental biotechnology include ecotoxicological risk assessment, heavy metal bioremediation, bioremediation of industrial wastewater and contaminated water.
- MeSH
- biodegradace MeSH
- biologické modely MeSH
- biotechnologie MeSH
- buněčné jádro genetika MeSH
- chloroplasty genetika MeSH
- Euglena genetika růst a vývoj metabolismus MeSH
- fylogeneze MeSH
- genom protozoální * MeSH
- kosmeceutika metabolismus MeSH
- potravní doplňky MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
In this study, we describe the mitochondrial genome of the excavate flagellate Euglena gracilis. Its gene complement is reduced as compared with the well-studied sister groups Diplonemea and Kinetoplastea. We have identified seven protein-coding genes: Three subunits of respiratory complex I (nad1, nad4, and nad5), one subunit of complex III (cob), and three subunits of complex IV (cox1, cox2, and a highly divergent cox3). Moreover, fragments of ribosomal RNA genes have also been identified. Genes encoding subunits of complex V, ribosomal proteins and tRNAs were missing, and are likely located in the nuclear genome. Although mitochondrial genomes of diplonemids and kinetoplastids possess the most complex RNA processing machineries known, including trans-splicing and editing of the uridine insertion/deletion type, respectively, our transcriptomic data suggest their total absence in E. gracilis. This finding supports a scenario in which the complex mitochondrial processing machineries of both sister groups evolved relatively late in evolution from a streamlined genome and transcriptome of their common predecessor.
