The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
Appl Microbiol Biotechnol. 2020 May;104(9):4093-4107. doi: 10.1007/s00253-020-10509-y. Epub 2020 Mar 11.
2-Phenylethanol (2-PE) is an important flavor compound but also impairs cell growth severely, which in turn blocks its bioproduction. However, the molecular mechanism of 2-PE tolerance is unclear. In this study, a superb 2-PE stress-tolerant and producing yeast, Candida glycerinogenes, was selected to uncover the underlying mechanism of 2-PE tolerance. We discovered that Hap5 is an essential regulator to 2-PE resistance, and its induction by 2-PE stress occurs at the post-transcriptional level, rather than at the transcriptional level. Under 2-PE stress, Hap5 is activated and imported into the nucleus rapidly. Then, the nuclear Hap5 binds to the glutathione synthetase (gsh2) promoter via CCAAT box, to induce the expression of gsh2 gene. The increased gsh2 expression contributes to enhanced cellular glutathione content, and consequently alleviates ROS accumulation, lipid peroxidation, and cell membrane damage caused by 2-PE toxicity. Specifically, increasing the expression of gsh2 is effective in improving not just 2-PE tolerance (33.7% higher biomass under 29 mM 2-PE), but also 2-PE production (16.2% higher). This study extends our knowledge of 2-PE tolerance mechanism and also provides a promising strategy to improve 2-PE production.
2-苯乙醇（2-PE）是一种重要的风味化合物，但严重抑制细胞生长，从而阻碍其生物生产。然而，2-PE 耐受的分子机制尚不清楚。在本研究中，选择了一株具有出色 2-PE 应激耐受和生产能力的酵母甘油假丝酵母，以揭示 2-PE 耐受的潜在机制。我们发现 Hap5 是 2-PE 抗性的必需调节剂，其受 2-PE 胁迫的诱导发生在转录后水平，而不是转录水平。在 2-PE 胁迫下，Hap5 被迅速激活并导入细胞核。然后，核 Hap5 通过 CCAAT 盒与谷胱甘肽合成酶（gsh2）启动子结合，诱导 gsh2 基因的表达。增加的 gsh2 表达有助于增强细胞内谷胱甘肽含量，从而减轻 2-PE 毒性引起的 ROS 积累、脂质过氧化和细胞膜损伤。具体来说，增加 gsh2 的表达不仅有效提高了 2-PE 的耐受性（在 29 mM 2-PE 下生物量提高了 33.7%），而且提高了 2-PE 的生产能力（产量提高了 16.2%）。本研究扩展了我们对 2-PE 耐受机制的认识，也为提高 2-PE 生产提供了一种有前途的策略。
