Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
Science Center for Future Foods, Jiangnan University, Wuxi, 214122, China.
Microb Cell Fact. 2023 Sep 13;22(1):180. doi: 10.1186/s12934-023-02195-y.
Saccharomyces cerevisiae has been used in the biosynthesis of acid products such as organic acids owing to its acid tolerance. Improving the acid tolerance of S. cerevisiae is beneficial for expanding its application range. Our previous study isolated the TAMC strain that was tolerant to a pH 2.3 through adaptive laboratory evolution; however, its mechanism underlying tolerance to low pH environment remains unclear.
In this study, through visual observation and order analysis of plasma membrane and membrane microdomains, we revealed that the membrane microdomains of TAMC strain play an indispensable role in acid tolerance. Transcriptomic analysis showed an increase in the expression of genes related to key components of membrane microdomains in TAMC strain. Furthermore, an obvious reduction was observed in the acid tolerance of the strain with sterol C-24 methyltransferase encoding gene ERG6 knockout for inhibiting membrane microdomain formation. Finally, colocalization analysis of H-ATPase PMA1 and plasma membrane protein PMP1 showed that disruption of membrane microdomains could inhibit the formation of the H-ATPase complex.
Membrane microdomains could provide a platform for forming H-ATPase complexes to facilitate intracellular H homeostasis, and thereby improve cell acid resistance. This study proposed a novel acid tolerance mechanism, providing a new direction for the rational engineering of acid-tolerant strains.
由于耐酸性，酿酒酵母已被用于合成酸产品，如有机酸。提高酿酒酵母的耐酸性有利于扩大其应用范围。我们之前的研究通过适应性实验室进化分离出了耐受 pH 2.3 的 TAMC 菌株，但它耐受低 pH 环境的机制尚不清楚。
在这项研究中，通过对质膜和膜微区的直观观察和有序分析，我们揭示了 TAMC 菌株的膜微区在耐酸中起着不可或缺的作用。转录组分析显示，TAMC 菌株中与膜微区关键成分相关的基因表达增加。此外，抑制膜微区形成的甾醇 C-24 甲基转移酶编码基因 ERG6 敲除菌株的耐酸性明显降低。最后，H+-ATPase PMA1 和质膜蛋白 PMP1 的共定位分析表明，破坏膜微区会抑制 H+-ATPase 复合物的形成。
膜微区可以为形成 H+-ATPase 复合物提供一个平台，促进细胞内 H+的稳态，从而提高细胞的耐酸性。本研究提出了一种新的耐酸机制，为耐酸菌株的合理工程设计提供了新的方向。
