Transcriptome analysis reveals multiple targets of erythritol-related transcription factor EUF1 in unconventional yeast Yarrowia Lipolytica

BACKGROUND

Erythritol is a four-carbon polyol with an unclear role in metabolism of some unconventional yeasts. Its production has been linked to the osmotic stress response, but the mechanism of stress protection remains unclear. Additionally, erythritol can be used as a carbon source. In the yeast Yarrowia lipolytica, its assimilation is activated by the transcription factor Euf1. The study investigates whether this factor can link erythritol to other processes in the cell.

RESULTS

The research was performed on two closely related strains of Y. lipolytica: MK1 and K1, where strain K1 has no functional Euf1. Cultures were carried out in erythritol-containing and erythritol-free media. Transcriptome analysis revealed the effect of Euf1 on the regulation of more than 150 genes. Some of these could be easily connected with different aspects of erythritol assimilation, such as: utilization pathway, a new potential isoform of transketolase, or polyol transporters. However, many of the upregulated genes have never been linked to metabolism of erythritol. The most prominent examples are the degradation pathway of branched-chain amino acids and the glyoxylate cycle. The high transcription of genes affected by Euf1 is still dependent on the erythritol concentration in the medium. Moreover, almost all up-regulated genes have an ATGCA motif in the promoter sequence.

CONCLUSIONS

These findings may be particularly relevant given the increasing use of erythritol-induced promoters in genetic engineering of Y. lipolytica. Moreover, use of this yeast in biotechnological processes often takes place under osmotic stress conditions. Erythritol might be produce as a by-product, thus better understanding of its influence on cell metabolism could facilitate processes optimization.

A teaching protocol demonstrating the use of EasyClone and CRISPR/Cas9 for metabolic engineering of Saccharomyces cerevisiae and Yarrowia lipolytica

We present a teaching protocol suitable for demonstrating the use of EasyClone and CRISPR/Cas9 for metabolic engineering of industrially relevant yeasts Saccharomyces cerevisiae and Yarrowia lipolytica, using β-carotene production as a case study. The protocol details all steps required to generate DNA parts, transform and genotype yeast, and perform a phenotypic screen to determine β-carotene production. The protocol is intended to be used as an instruction manual for a two-week practical course aimed at M.Sc. and Ph.D. students. The protocol details all necessary steps for students to engineer yeast to produce β-carotene and serves as a practical introduction to the principles of metabolic engineering including the concepts of boosting native precursor supply and alleviating rate-limiting steps. It also highlights key differences in the metabolism and heterologous production capacity of two industrially relevant yeast species. The protocol is divided into daily experiments covering a two-week period and provides detailed instructions for every step meaning this protocol can be used 'as is' for a teaching course or as a case study for how yeast can be engineered to produce value-added molecules.

OP0070 ONSET TO DIAGNOSIS TIME PREDICTS SURVIVAL RATE IN TAKAYASU ARTERITIS

Background:

Takayasu arteritis (TA) is large vessel vasculitis. In spite of relatively high 5 to 15 years survival rate, TA affects young persons and causes major cardiovascular events, disability and preterm deaths [1]. Nowadays, though new high-resolution visualization and effective treatment options are available, quite a large number of TA patients remain undiagnosed and untreated for years [2].

Objectives:

To assess the influence of timely TA diagnosis and treatment initiation on the survival rate and cardiovascular events risk.

Methods:

A retrospective cohort study included 183 patients (139 females, 44 males), enrolled during the period from 1979 to 2018 after TA diagnosis verification according to ACR1990 criteria [3]. All subjects have been followed up at the Sverdlovsk Regional Clinical Hospital 1. Cox regression model was used to compare survival rate.

Results:

By enrollment, females median age was 35 [25%-75%: 24 - 44] and in males median age was 34 [26 -42]. Median time duration from the first symptoms onset to the diagnosis verification was 3 [1-7] years in females and [1.5 - 8] years in males. The most common affected arteries were subclavian (55%), carotid (53%), and renal (42%). 5-year survival rate was 92%; 10-year survival rate was 90%; 15-year survival rate was 80%. The median term of survival was 34 [20 - 41] years. 31 deaths (18 males and 13 females) occurred during the follow-up period. Median age of death was 36 [32-44] in females, and 50 [40-57]) in males. The average disease course duration at the time of death was 9.25 years, median term being 6.5 [3-16] in females and 5 [3-10] in males. Also a total of 72 cardiovascular events were recorded during the follow-up period: 27 in men and 45 in women. The median duration of AT course by the development of the first ever event was 10 (5 -20). There were 24 cases of ischemic stroke, 3 transient ischemic attacks, 4 cases of hemorrhagic stroke. Median age of the first ever event was 38 (30 - 49.5). Time duration 4 years or more from AT symptoms onset to diagnosis was associated with significantly more frequent cardiovascular events (OR 1.8; 95% CI 1.07 – 3.34); and premature deaths (see table) by the 5th year of follow up (OR 2.9; 1.27- 6.55).

Conclusion:

In a retrospective cohort, time duration 4 years or more from TA symptoms onset to diagnosis verification was associated with higher risk of cardiovascular events and lower survival rate.

References:

[1]Mirouse C. et al. Ann. Rheum. Dis. 2018; 77(2): 10-48

[2]Dejaco C. et al. Ann. Rheum. Dis. 2018;77: 636-643

[3]Arend W.P. et al. Arthritis Rheum. 1990; 3(8): 1129-1134.

Disclosure of Interests:

Artem Popov Speakers bureau: Novartis, Menarini, AstraZeneca, Pfizer, Severnaya Zvezda, Romepharm, Irina Borodina: None declared, Lubov Shardina: None declared

Metabolic engineering of Saccharomyces cerevisiae for the de novo production of psilocybin and related tryptamine derivatives

Psilocybin is a tryptamine-derived psychoactive alkaloid found mainly in the fungal genus Psilocybe, among others, and is the active ingredient in so-called “magic mushrooms”. Although its notoriety originates from its psychotropic properties and popular use as a recreational drug, clinical trials have recently recognized psilocybin as a promising candidate for the treatment of various psychological and neurological afflictions. In this work, we demonstrate the de novo biosynthetic production of psilocybin and related tryptamine derivatives in Saccharomyces cerevisiae by expression of a heterologous biosynthesis pathway sourced from Psilocybe cubensis. Additionally, we achieve improved product titers by supplementing the pathway with a novel cytochrome P450 reductase from P. cubensis. Further rational engineering resulted in a final production strain producing 627 ± 140 mg/L of psilocybin and 580 ± 276 mg/L of the dephosphorylated degradation product psilocin in triplicate controlled fed-batch fermentations in minimal synthetic media. Pathway intermediates baeocystin, nor norbaeocystin as well the dephosphorylated baeocystin degradation product norpsilocin were also detected in strains engineered for psilocybin production. We also demonstrate the biosynthetic production of natural tryptamine derivative aeruginascin as well as the production of a new-to-nature tryptamine derivative N-acetyl-4-hydroxytryptamine. These results lay the foundation for the biotechnological production of psilocybin in a controlled environment for pharmaceutical applications, and provide a starting point for the biosynthetic production of other tryptamine derivatives of therapeutic relevance.

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De novo production of psilocybin in S. cerevisiae.

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Expression of a novel cytochrome P450 reductase from P. cubensis significantly boosts production.

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Rational metabolic engineering results in 627 mg/L psilocybin production.

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Production of natural and new-to-nature tryptamine derivatives demonstrated including norbaeocystin, baeocystin, and aeruginascin.