School of Microbiology, APC Microbiome Ireland, Environmental Research Institute and SUSFERM Centre, University College Cork, Cork T12 K8AF, Ireland.
Department of Biology and Biological Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
Microbiology (Reading). 2022 Mar;168(3). doi: 10.1099/mic.0.001148.
It is important to understand the basis of thermotolerance in yeasts to broaden their application in industrial biotechnology. The capacity to run bioprocesses at temperatures above 40 °C is of great interest but this is beyond the growth range of most of the commonly used yeast species. In contrast, some industrial yeasts such as can grow at temperatures of 45 °C or higher. Such species are valuable for direct use in industrial biotechnology and as a vehicle to study the genetic and physiological basis of yeast thermotolerance. In previous work, we reported that evolutionarily young genes disproportionately changed expression when yeast were growing under stressful conditions and postulated that such genes could be important for long-term adaptation to stress. Here, we tested this hypothesis in by identifying and studying species-specific genes that showed increased expression during high-temperature growth. Twelve such genes were identified and 11 were successfully inactivated using CRISPR-mediated mutagenesis. One gene, , is required for competitive growth at high temperature, supporting the hypothesis that evolutionary young genes could play roles in adaptation to harsh environments. is predicted to encode an 83 aa peptide, and RNA sequencing and ribo-sequencing were used to confirm transcription and translation of the gene. The precise function of KLMX_70384 remains unknown but some features are suggestive of RNA-binding activity. The gene is located in what was previously considered an intergenic region of the genome, which lacks homologues in other yeasts or in databases. Overall, the data support the hypothesis that genes that arose in after the speciation event that separated and contribute to some of its unique traits.
了解酵母耐热性的基础对于拓宽其在工业生物技术中的应用非常重要。在 40°C 以上的温度下运行生物工艺的能力非常重要，但这超出了大多数常用酵母物种的生长范围。相比之下，一些工业酵母，如 ，可以在 45°C 或更高的温度下生长。这些物种对于直接在工业生物技术中使用以及作为研究酵母耐热性遗传和生理基础的载体都非常有价值。在之前的工作中，我们报告说，在酵母生长于应激条件下时，进化较年轻的基因不成比例地改变表达，并且推测这些基因可能对于长期适应应激很重要。在这里，我们通过鉴定和研究在高温生长过程中表达增加的物种特异性基因来检验这一假说。鉴定出了 12 个这样的基因，并使用 CRISPR 介导的诱变成功地失活了 11 个。一个基因 ，对于高温下的竞争生长是必需的，这支持了进化较年轻的基因可能在适应恶劣环境中发挥作用的假说。 被预测编码一个 83 个氨基酸的肽，RNA 测序和核糖体测序被用来证实该基因的转录和翻译。KLMX_70384 的精确功能尚不清楚，但一些特征提示它具有 RNA 结合活性。该基因位于先前被认为是基因组中基因间区的位置，在其他酵母或数据库中没有同源物。总的来说，数据支持这样的假说，即在 和 发生物种分化之后出现的基因有助于其一些独特的特征。
