School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan.
Center for Biosystem Dynamics Research, RIKEN, 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan.
World J Microbiol Biotechnol. 2023 Jul 21;39(10):255. doi: 10.1007/s11274-023-03696-z.
We previously isolated a mutant of Saccharomyces cerevisiae strain 85_9 whose glycerol assimilation was improved through adaptive laboratory evolution. To investigate the mechanism for this improved glycerol assimilation, genome resequencing of the 85_9 strain was performed, and the mutations in the open reading frame of HOG1, SIR3, SSB2, and KGD2 genes were found. Among these, a frameshift mutation in the HOG1 open reading frame was responsible for the improved glycerol assimilation ability of the 85_9 strain. Moreover, the HOG1 gene disruption improved glycerol assimilation. As HOG1 encodes a mitogen-activated protein kinase (MAPK), which is responsible for the signal transduction cascade in response to osmotic stress, namely the high osmolarity glycerol (HOG) pathway, we investigated the effect of the disruption of PBS2 gene encoding MAPK kinase for Hog1 MAPK on glycerol assimilation, revealing that PBS2 disruption can increase glycerol assimilation. These results indicate that loss of function of Hog1 improves glycerol assimilation in S. cerevisiae. However, single disruption of the SSK2, SSK22 and STE11 genes encoding protein kinases responsible for Pbs2 phosphorylation in the HOG pathway did not increase glycerol assimilation, while their triple disruption partially improved glycerol assimilation in S. cerevisiae. In addition, the HOG1 frameshift mutation did not improve glycerol assimilation in the STL1-overexpressing RIM15 disruptant strain, which was previously constructed with high glycerol assimilation ability. Furthermore, the effectiveness of the HOG1 disruptant as a bioproduction host was validated, indicating that the HOG1 CYB2 double disruptant can produce L-lactic acid from glycerol.
我们之前通过适应性实验室进化,分离到了一株酿酒酵母 85_9 的突变株,该突变株的甘油同化能力得到了提高。为了研究这种甘油同化能力提高的机制,我们对 85_9 菌株进行了基因组重测序,并发现了 HOG1、SIR3、SSB2 和 KGD2 基因的开放阅读框中的突变。其中,HOG1 开放阅读框的移码突变导致了 85_9 菌株甘油同化能力的提高。此外,HOG1 基因的敲除也提高了甘油同化能力。由于 HOG1 编码一种丝裂原活化蛋白激酶(MAPK),该激酶负责响应渗透压胁迫的信号转导级联反应,即高渗透压甘油(HOG)途径,我们研究了 MAPK 激酶 PBS2 基因敲除对 Hog1 MAPK 的影响,结果表明 PBS2 敲除可以增加甘油同化。这些结果表明,Hog1 的功能丧失可以改善酿酒酵母的甘油同化。然而,仅敲除负责 Pbs2 磷酸化的 SSK2、SSK22 和 STE11 基因编码的蛋白激酶并不能增加甘油同化,而它们的三重敲除则部分改善了酿酒酵母的甘油同化。此外,HOG1 移码突变并不能提高在具有高甘油同化能力的 STL1 过表达 RIM15 敲除突变株中的甘油同化能力。此外,验证了 HOG1 敲除突变体作为生物生产宿主的有效性,表明 HOG1 CYB2 双敲除突变体可以从甘油生产 L-乳酸。