The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (-)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9). In addition, another key enzyme in sterol biosynthesis, squalene epoxidase (ERG1) was inhibited by an experimentally defined amount of the inhibitor terbinafine in order to reduce flux of squalene towards ergosterol biosynthesis while retaining sufficient activity to maintain cell viability and growth. Heterologous expression of a promiscuous variant of Bacillus megaterium tetraprenyl-β-curcumene cyclase (BmeTC-D373C), which has been shown to be able to catalyse the conversion of squalene to 3-deoxyachillol and then further to (+)-ambrein resulted in production of these triterpenoids in S. cerevisiae for the first time. Triterpenoid yields are comparable with the best microbial production chassis described in literature so far, the methylotrophic yeast Pichia pastoris. Consequently, we discuss similarities and differences of these two yeast species when applied for whole-cell (+)-ambrein production.

中文翻译：

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酿酒酵母工程生产（+）-ambrein。

三萜类（+）-安布雷林是龙涎香的主要成分，龙涎香是抹香鲸的共同腐殖质，仅在海岸上很少见。（+）-ambrein氧化降解后，会形成几个香料分子，其中（-）-ambrox是香料行业中价值最高的化合物之一。为了生成酿酒酵母全细胞生物催化剂以生产（+）-纤连蛋白，在甲羟戊酸和固醇的生物合成途径中，即N末端被截短的3-羟基-3-甲基戊二酰辅酶A还原酶1（tHMG）和角鲨烯合酶（ERG9）。此外，固醇生物合成中的另一种关键酶 角鲨烯环氧酶（ERG1）被实验确定的抑制剂特比萘芬抑制，以减少角鲨烯向麦角固醇生物合成的通量，同时保持足够的活性以维持细胞活力和生长。巨大芽孢杆菌四异戊二烯-β-姜黄素环化酶（BmeTC-D373C）的混杂变体的异源表达已被证明能够催化角鲨烯转化为3-脱氧阿奇洛尔然后进一步转化为（+）-ambrein导致生产这些三萜类化合物首次出现在酿酒酵母中。三萜类化合物的产量可与迄今为止文献中描述的最佳微生物生产底盘，即甲基营养酵母巴斯德毕赤酵母。因此，我们讨论了将两种酵母应用于全细胞（+）-纤连蛋白生产时的异同。