Unlocking the biological potential ofEuglena gracilis: evolution, cell biology and significance to parasitism

Abstract

Photosynthetic euglenids are major components of aquatic ecosystems and relatives of trypanosomes. Euglena gracilis has considerable biotechnological potential and great adaptability, but exploitation remains hampered by the absence of a comprehensive gene catalogue. We address this by genome, RNA and protein sequencing: the E. gracilis genome is >2Gb, with 36,526 predicted proteins. Large lineage-specific paralog families are present, with evidence for flexibility in environmental monitoring, divergent mechanisms for metabolic control, and novel solutions for adaptation to extreme environments. Contributions from photosynthetic eukaryotes to the nuclear genome, consistent with the shopping bag model are found, together with transitions between kinetoplastid and canonical systems. Control of protein expression is almost exclusively post-transcriptional. These data are a major advance in understanding the nuclear genomes of euglenids and provide a platform for investigating the contributions of E. gracilis and its relatives to the biosphere.

Bioproducts From Euglena gracilis: Synthesis and Applications

“…Improvement of the performance of E. gracilis has mainly relied on developing cultivation conditions to favour the synthesis of the compound of interest, followed by scale-up of the cultivation volume, because of a general lack of genetic information on the metabolic pathways leading to the various bioproducts (O'Neill et al, 2015a; Wang et al, 2018). While a draft genome assembly and initial features of the genome have been made available, a complete annotated genome sequence is not on hand as yet (O'Neill et al, 2015a; Ebenezer et al, 2017). The large size and complexity of the E. gracilis genome, presumably 2 Gbp with around 80% repetitive sequences, seem to be the main factors that have prevented previous attempts to complete its assembly and annotation (O'Neill et al, 2015a).…”

Evolution of protein trafficking in kinetoplastid parasites: Complexity and pathogenesis

“…Leishmania is also capable of secretion of highly glycosylated proteins, facilitating transmission by the sandfly vector. Beyond the trypanosomatida, the free‐living Bodo saltans and Euglena gracilis both possess elements of the LPG biosynthetic pathway within their genomes . It is plausible that the parasitic species evolved from free‐living forms to initially infect arthropods and only later acquired the ability to infect mammals or vascular plants, and that LPG has a rather fundamental role that is unconnected to parasitism per se, perhaps as a general protective molecule.…”

Circular extrachromosomal DNA inEuglena gracilisunder normal and stress conditions

“…Euglenids, members of Euglenozoa group, are cosmopolitan unicellular algae with potential as a source of biofuels, nutrients, and antioxidants [26]- [29]. Euglena gracilis is the best characterized and most frequently used species [30]- [34]. It remains the only representative of the Euglena genus with a publicly available genome draft.…”

“…It remains the only representative of the Euglena genus with a publicly available genome draft. This preliminary assembly is highly fragmented (N 50 = 955 bp) and predominantly unannotated [30], [35]. Initially, genomes of euglenids were presumed to be several times larger than the human genome.…”