Production and derivate composition of trisporoids in extended fermentation of Blakeslea trispora

SR5AL serves as a key regulatory gene in lycopene biosynthesis by Blakeslea trispora

BACKGROUND

Trisporic acids are considered to be key regulators of carotenoid biosynthesis and sexual reproduction in zygomycetes, but the mechanisms underlying this regulation have not been fully elucidated.

RESULTS

In this study, the relationships between trisporic acids and lycopene synthesis were investigated in Blakeslea trispora. The lycopene concentration in single fermentation by the (-) strain with the addition of 24 μg/L trisporic acids was slightly higher than that observed in mated fermentation. After transcriptomic analysis, a steroid 5α-reductase-like gene, known as SR5AL in B. trispora, was first reported. 5α-Reductase inhibitors reduced lycopene biosynthesis and downregulated the expression of sex determination and carotenoid biosynthesis genes. Overexpression of the SR5AL gene upregulated these genes, regardless of whether trisporic acids were added.

CONCLUSION

These findings indicated that the SR5AL gene is a key gene associated with the response to trisporic acids.

Early and late trisporoids differentially regulate β-carotene production and gene transcript Levels in the mucoralean fungi Blakeslea trispora and Mucor mucedo

The multistep cleavage of carotenoids in Mucorales during the sexual phase results in a cocktail of trisporic acid (C18) sex pheromones. We hypothesized that the C18 trisporoid intermediates have a specific regulatory function for sex pheromone production and carotenogenesis that varies with genus/species and vegetative and sexual phases of their life cycles. Real-time quantitative PCR kinetics determined for Blakeslea trispora displayed a very high transcript turnover in the gene for carotenoid cleavage dioxygenase, tsp3, during the sexual phase. An in vivo enzyme assay and chromatographic analysis led to the identification of β-apo-12'-carotenal as the first apocarotenoid involved in trisporic acid biosynthesis in B. trispora. Supplementation of C18 trisporoids, namely D'orenone, methyl trisporate C, and trisporin C, increased tsp3 transcripts in the plus compared to minus partners. Interestingly, the tsp1 gene, which is involved in trisporic acid biosynthesis, was downregulated compared to tsp3 irrespective of asexual or sexual phase. Only the minus partners of both B. trispora and Mucor mucedo had enhanced β-carotene production after treatment with C20 apocarotenoids, 15 different trisporoids, and their analogues. We conclude that the apocarotenoids and trisporoids influence gene transcription and metabolite production, depending upon the fungal strain, corresponding genus, and developmental phase, representing a "chemical dialect" during sexual communication.

Biosynthesis, extraction, purification, and analysis of trisporoid sexual communication compounds from mated cultures of Blakeslea trispora

The zygomycete Blakeslea trispora produces high amounts of the general zygomycete β-carotene-derived sexual signal compounds, the trisporoids. These can be isolated from the culture medium and purified by extraction with organic solvents followed by thin layer chromatography. Concentration is determined spectrophotometrically using specific extinction coefficients established for some members of this compound family. The effect of the extraction and activity of the isolated compounds is best tested physiologically, exploiting the ability of trisporoids to induce the formation of sexually committed hyphae, the zygophores, in other zygomycete species. Methods for B. trispora culture, trisporoid extraction, and further analyses of trisporoids are described in this chapter.

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the key step.