Chen Hong-Qi, Xing Qi, Cheng Cheng, Zhang Ming-Ming, Liu Chen-Guang, Champreda Verawat, Zhao Xin-Qing
State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand.
Front Bioeng Biotechnol. 2022 Mar 25;10:837813. doi: 10.3389/fbioe.2022.837813. eCollection 2022.
Robust yeast strains that are tolerant to multiple stress environments are desired for an efficient biorefinery. Our previous studies revealed that zinc sulfate serves as an important nutrient for stress tolerance of budding yeast . Acetic acid is a common inhibitor in cellulosic hydrolysate, and the development of acetic acid-tolerant strains is beneficial for lignocellulosic biorefineries. In this study, comparative proteomic studies were performed using cultured under acetic acid stress with or without zinc sulfate addition, and novel zinc-responsive proteins were identified. Among the differentially expressed proteins, the protein kinase Kic1p and the small rho-like GTPase Cdc42p, which is required for cell integrity and regulation of cell polarity, respectively, were selected for further studies. Overexpression of and endowed with faster growth and ethanol fermentation under the stresses of acetic acid and mixed inhibitors, as well as in corncob hydrolysate. Notably, the engineered yeast strains showed a 12 h shorter lag phase under the three tested conditions, leading to up to 52.99% higher ethanol productivity than that of the control strain. Further studies showed that the transcription of genes related to stress response was significantly upregulated in the engineered strains under the stress condition. Our results in this study provide novel insights in exploring zinc-responsive proteins for applications of synthetic biology in developing a robust industrial yeast.
高效生物炼制需要能耐受多种应激环境的健壮酵母菌株。我们之前的研究表明，硫酸锌是出芽酵母应激耐受的重要营养素。乙酸是纤维素水解产物中的常见抑制剂，开发耐乙酸菌株有利于木质纤维素生物炼制。在本研究中，我们对添加或不添加硫酸锌的情况下在乙酸胁迫下培养的酵母进行了比较蛋白质组学研究，并鉴定了新的锌响应蛋白。在差异表达的蛋白质中，分别选择了细胞完整性和细胞极性调节所需的蛋白激酶Kic1p和小rho样GTP酶Cdc42p进行进一步研究。Kic1p和Cdc42p的过表达使酵母在乙酸和混合抑制剂胁迫下以及在玉米芯水解产物中生长更快且乙醇发酵能力更强。值得注意的是，在三种测试条件下，工程酵母菌株的延迟期缩短了12小时，乙醇生产率比对照菌株高出52.99%。进一步研究表明，在应激条件下，工程菌株中与应激反应相关的基因转录显著上调。我们在本研究中的结果为探索锌响应蛋白以用于合成生物学在开发健壮工业酵母中的应用提供了新的见解。
