Zhao Shuyi, Yuan Bing, Wang Xueqing, Chen Hongqi, Zhao Xinqing, Bai Fengwu
School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Microbial Metabolism, Shanghai 200240, China.
Sheng Wu Gong Cheng Xue Bao. 2021 Dec 25;37(12):4293-4302. doi: 10.13345/j.cjb.200787.
Acetic acid is a common inhibitor present in lignocellulosic hydrolysate. Development of acetic acid tolerant strains may improve the production of biofuels and bio-based chemicals using lignocellulosic biomass as raw materials. Current studies on stress tolerance of yeast Saccharomyces cerevisiae have mainly focused on transcription control, but the role of transfer RNA (tRNA) was rarely investigated. We found that some tRNA genes showed elevated transcription levels in a stress tolerant yeast strain. In this study, we further investigated the effects of overexpressing an arginine transfer RNA gene tR(ACG)D and a leucine transfer RNA gene tL(CAA)K on cell growth and ethanol production of S. cerevisiae BY4741 under acetic acid stress. The tL(CAA)K overexpression strain showed a better growth and a 29.41% higher ethanol productivity than that of the control strain. However, overexpression of tR(ACG)D showed negative influence on cell growth and ethanol production. Further studies revealed that the transcriptional levels of HAA1, MSN2, and MSN4, which encode transcription regulators related to stress tolerance, were up-regulated in tL(CAA)K overexpressed strain. This study provides an alternative strategy to develop robust yeast strains for cellulosic biorefinery, and also provides a basis for investigating how yeast stress tolerance is regulated by tRNA genes.
乙酸是木质纤维素水解产物中常见的一种抑制剂。开发耐乙酸菌株可能会提高以木质纤维素生物质为原料生产生物燃料和生物基化学品的产量。目前关于酿酒酵母应激耐受性的研究主要集中在转录调控方面，但转运RNA（tRNA）的作用鲜有研究。我们发现一些tRNA基因在耐应激酵母菌株中呈现转录水平升高的现象。在本研究中，我们进一步探究了过表达精氨酸转运RNA基因tR(ACG)D和亮氨酸转运RNA基因tL(CAA)K对乙酸胁迫下酿酒酵母BY4741细胞生长及乙醇产量的影响。tL(CAA)K过表达菌株表现出更好的生长情况，乙醇生产率比对照菌株高29.41%。然而，tR(ACG)D的过表达对细胞生长和乙醇产量产生了负面影响。进一步研究表明，在tL(CAA)K过表达菌株中，编码与应激耐受性相关转录调节因子的HAA1、MSN2和MSN4的转录水平上调。本研究为开发用于纤维素生物炼制的健壮酵母菌株提供了一种替代策略，也为研究tRNA基因如何调控酵母应激耐受性提供了依据。
