Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental Remediation, School of Life Sciences, Huaibei Normal University, Huaibei, Anhui, 235000, PR China.
Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental Remediation, School of Life Sciences, Huaibei Normal University, Huaibei, Anhui, 235000, PR China.
Enzyme Microb Technol. 2020 Oct;140:109641. doi: 10.1016/j.enzmictec.2020.109641. Epub 2020 Aug 5.
The accumulation of glycerol is essential for yeast viability upon hyperosmotic stress. In this study, the STL1 homolog KmSTL1, encoding a putative glycerol transporter contributing to cell osmo-tolerance, was identified in Kluyveromyces marxianus NBRC1777. We constructed the KmSTL1, KmGPD1, and KmFPS1 single-deletion mutants and the KmSTL1/KmGPD1 and KmSTL1/KmFPS1 double-deletion mutants of K. marxianus. Deletion of KmSTL1 or KmGPD1 resulted in K. marxianus cell sensitization to hyperosmotic stress, whereas deletion of KmFPS1 improved stress tolerance. The expression of KmSTL1 was osmotically induced, whereas that of KmFPS1 was osmotically inhibited. The expression of KmGPD1 was constitutive and continuous in the ΔKmSTL1 mutant strain but inhibited in the ΔKmFPS1 mutant strain due to feedback suppression by glycerol. In summary, our findings indicated that K. marxianus would increase glycerol synthesis by increasing GPD1 expression, increase glycerol import from the extracellular environment by increasing STL1 expression, and reduce glycerol efflux by reducing FPS1 expression under hyperosmotic stress.
甘油的积累对于酵母在高渗胁迫下的生存能力至关重要。在这项研究中，我们在马克斯克鲁维酵母 NBRC1777 中鉴定出了 STL1 同源物 KmSTL1，它编码一种可能的甘油转运蛋白，有助于细胞耐渗透压。我们构建了 KmSTL1、KmGPD1 和 KmFPS1 的单缺失突变体以及 KmSTL1/KmGPD1 和 KmSTL1/KmFPS1 的双缺失突变体。KmSTL1 或 KmGPD1 的缺失导致马克斯克鲁维酵母细胞对高渗胁迫敏感，而 KmFPS1 的缺失则提高了其耐受能力。KmSTL1 的表达受到渗透压的诱导，而 KmFPS1 的表达则受到渗透压的抑制。KmGPD1 的表达在 ΔKmSTL1 突变株中是组成型和连续的，但在 ΔKmFPS1 突变株中受到反馈抑制，因为甘油抑制了其表达。总之，我们的研究结果表明，在高渗胁迫下，马克斯克鲁维酵母通过增加 GPD1 表达来增加甘油合成，通过增加 STL1 表达来增加细胞外环境中的甘油摄取，并通过降低 FPS1 表达来减少甘油外排。
