Increasing the metabolic flux of the mevalonate pathway, reducing the metabolic flux of competing pathway and utilizing the diauxie-inducible system constructed by GAL promoters are strategies commonly used in yeast metabolic engineering for the production of terpenoids. Using these strategies, we constructed a series of yeast strains with a strengthened mevalonate pathway and finally produced 336.5 mg/L nerolidol in a shake flask. The spliced HAC1 mRNA assay indicated that the unfolded protein response (UPR) occurred in the strains that we constructed. UPR strains exhibited the low transcriptional activities of GAL1 promoter. HAC1-overexpressing strain exhibited dramatically enhanced transcriptional activity of GAL1 promoter at 72 h of fermentation in flasks. HAC1 overexpression also increased the nerolidol titer by 47.7 %, reaching 497.0 mg/L and increased cell vitality. RNA-seq showed that the genes whose transcription responded to HAC1-overexpression were involved in the regulation of monocarboxylic acid metabolic processes and cellular amino acid biosynthetic process, indicating that the metabolic regulation may be part of the reason of the improved nerolidol synthesis. Our findings enrich the knowledge of the relationship between the construction of sesquiterpene-producing cell factories and UPR regulation. This study provides an effective strategy for sesquiterpene production in yeast.

中文翻译：

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转录因子 HAC1 的过度表达提高了工程酵母中橙花醇的产量

增加甲羟戊酸途径的代谢通量、降低竞争途径的代谢通量和利用由 GAL 启动子构建的双酶诱导系统是酵母代谢工程中常用的生产萜类化合物的策略。使用这些策略，我们构建了一系列具有强化甲羟戊酸途径的酵母菌株，最终在摇瓶中产生了 336.5 mg/L 橙花醇。剪接的 HAC1 mRNA 测定表明未折叠蛋白反应 (UPR) 在我们构建的菌株中发生。UPR 菌株表现出 GAL1 启动子的低转录活性。HAC1 过表达菌株在烧瓶中发酵 72 小时时表现出显着增强的 GAL1 启动子转录活性。HAC1 过表达还将橙花醇滴度提高了 47.7%，达到 497。0 mg/L 并增加细胞活力。RNA-seq显示转录响应HAC1过表达的基因参与了单羧酸代谢过程和细胞氨基酸生物合成过程的调控，表明代谢调控可能是橙花醇合成改善的部分原因。我们的发现丰富了有关倍半萜烯生产细胞工厂的构建与 UPR 监管之间关系的知识。该研究为酵母中倍半萜的生产提供了一种有效的策略。表明代谢调节可能是橙花醇合成改善的部分原因。我们的发现丰富了有关倍半萜烯生产细胞工厂的构建与 UPR 监管之间关系的知识。该研究为酵母中倍半萜的生产提供了一种有效的策略。表明代谢调节可能是橙花醇合成改善的部分原因。我们的发现丰富了有关倍半萜烯生产细胞工厂的构建与 UPR 监管之间关系的知识。该研究为酵母中倍半萜的生产提供了一种有效的策略。