College of Architecture and Environment, Sichuan University, No. 24, South Section 1, First Ring Road, Chengdu, 610065, Sichuan, China.
Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
Microb Cell Fact. 2022 May 28;21(1):105. doi: 10.1186/s12934-022-01822-4.
Various inhibitors coexist in the hydrolysate derived from lignocellulosic biomass. They inhibit the performance of Saccharomyces cerevisiae and further restrict the development of industrial bioethanol production. Transcription factors are regarded as targets for constructing robust S. cerevisiae by genetic engineering. The tolerance-related transcription factors have been successively reported, while their regulatory mechanisms are not clear. In this study, we revealed the regulation mechanisms of Haa1p and Tye7p that had outstanding contributions to the improvement of the fermentation performance and multiple inhibitor tolerance of S. cerevisiae.
Comparative transcriptomic analyses were applied to reveal the regulatory mechanisms of Haa1p and Tye7p under mixed sugar fermentation conditions with mixed inhibitors [acetic acid and furfural (AFur)] or without inhibitor (C) using the original strain s6 (S), the HAA1-overexpressing strain s6H3 (H), and the TYE7-overexpressing strain s6T3 (T). The expression of the pathways related to carbohydrate, amino acid, transcription, translation, cofactors, and vitamins metabolism was enhanced in the strains s6H3 and s6T3. Compared to C_H vs. C_S group, the unique DEGs in AFur_H vs. AFur_S group were further involved in oxidative phosphorylation, purine metabolism, vitamin B6 metabolism, and spliceosome under the regulation of Haa1p. A similar pattern appeared under the regulation of Tye7p, and the unique DEGs in AFur_T vs. AFur_S group were also involved in riboflavin metabolism and spliceosome. The most significant difference between the regulations of Haa1p and Tye7p was the intracellular energy supply. Haa1p preferred to enhance oxidative phosphorylation, while Tye7p tended to upregulate glycolysis/gluconeogenesis.
Global gene expressions could be rewired with the overexpression of HAA1 or TYE7. The positive perturbations of energy and amino acid metabolism were beneficial to the improvement of the fermentation performance of the strain. Furthermore, strengthening of key cofactor metabolism, and transcriptional and translational regulation were helpful in improving the strain tolerance. This work provides a novel and comprehensive understanding of the regulation mechanisms of Haa1p and Tye7p in S. cerevisiae.
木质纤维素生物质水解物中存在多种抑制剂。它们会抑制酿酒酵母的性能，进一步限制工业生物乙醇生产的发展。转录因子被认为是通过基因工程构建酿酒酵母的目标。已经相继报道了与耐受性相关的转录因子，但它们的调控机制尚不清楚。在这项研究中，我们揭示了 Haa1p 和 Tye7p 的调控机制，它们对提高酿酒酵母的发酵性能和多种抑制剂耐受性有突出贡献。
采用比较转录组分析方法，在含有混合抑制剂（乙酸和糠醛（AFur））或无抑制剂（C）的混合糖发酵条件下，对原始菌株 s6（S）、HAA1 过表达菌株 s6H3（H）和 TYE7 过表达菌株 s6T3（T）进行了 Haa1p 和 Tye7p 的调控机制研究。在菌株 s6H3 和 s6T3 中，与碳水化合物、氨基酸、转录、翻译、辅助因子和维生素代谢相关的途径表达增强。与 C_H 相比，AFur_H 与 C_S 相比，Haa1p 调控下的差异表达基因（DEGs）进一步参与氧化磷酸化、嘌呤代谢、维生素 B6 代谢和剪接体。在 Tye7p 调控下也出现了类似的模式，AFur_T 与 AFur_S 相比，差异表达基因也参与核黄素代谢和剪接体。Haa1p 和 Tye7p 调控的最大区别在于细胞内能量供应。Haa1p 更喜欢增强氧化磷酸化，而 Tye7p 倾向于上调糖酵解/糖异生。
过表达 HAA1 或 TYE7 可以重新布线全局基因表达。能量和氨基酸代谢的正向扰动有利于提高菌株的发酵性能。此外，加强关键辅因子代谢、转录和翻译调控有助于提高菌株的耐受性。这项工作为酿酒酵母中 Haa1p 和 Tye7p 的调控机制提供了一个新的、全面的认识。
