Production of retinoic acid by engineered Saccharomyces cerevisiae using an endogenous aldehyde dehydrogenase

Abstract

Retinoic acid (RA), a vitamin A (retinol)‐derived lipophilic compound, is involved in various physiological functions. The demand for RA is growing in the pharmaceutical industry, but RA biosynthesis is still in its infancy compared to other forms of retinoids such as retinol and retinal, largely due to the lack of efficient retinal dehydrogenases. To achieve effective biosynthesis of RA, the catalytic activities of exogenous retinal dehydrogenases were comparatively analyzed in a previously constructed retinoids‐producing Saccharomyces cerevisiae strain, followed by mining of endogenous enzymes with higher retinal dehydrogenase activities using homology‐based search. After confirming the retinal oxidation activity of the endogenous aldehyde dehydrogenase Hfd1 using in vivo and in vitro experiments, it was overexpressed in multiple copies, and the resulting strain produced 99.71 mg/L of RA in shake‐flask cultures. Finally, 545.28 mg/L of RA was produced in fed‐batch fermentation. This study suggests the yeast endogenous Hfd1 as a potent catalyst for RA biosynthesis, and demonstrates the potential of yeast as a platform for RA production.

Efficient Secretory Production of δ-Tocotrienol by Combining Pathway Modularization and Transportation Engineering

“…The potent antioxidant activity of tocotrienols makes it particularly important to prevent oxidation. As observed for retinol production, prevention of product oxidation could significantly elevate its titer. , Thus, the formation of inclusion complexes with β-cyclodextrin provided a hydrophobic environment for the storage of δ-tocotrienol outside of cells, while also reducing loss due to oxidation, leading to the enhanced production and secretion of δ-tocotrienol.…”

“…As observed for retinol production, prevention of product oxidation could significantly elevate its titer. 45,46 Thus, the formation of inclusion complexes with βcyclodextrin provided a hydrophobic environment for the storage of δ-tocotrienol outside of cells, while also reducing loss due to oxidation, leading to the enhanced production and secretion of δ-tocotrienol. In order to maximize the secretion and synthesis of δtocotrienol, the amount and timing of 2-HP-β-CD addition were optimized.…”

Multi-level engineering of Saccharomyces cerevisiae for the synthesis and accumulation of retinal

“…20 Recently, the retinal oxidation activity of Hfd1 was further confirmed by an in vitro assay. 21 Considering the above literature, we decided to delete alcohol/aldehyde dehydrogenases such as Adh6, Adh7, Sfa1, Gre2 and Hfd1 (Fig. 2A).…”