Karhumaa Kaisa, Påhlman Anna-Karin, Hahn-Hägerdal Bärbel, Levander Fredrik, Gorwa-Grauslund Marie-F
Department of Applied Microbiology, Lund University, PO Box 124, SE-22100 Lund, Sweden.
Yeast. 2009 Jul;26(7):371-82. doi: 10.1002/yea.1673.
Xylose fermentation in yeast has been a target of research for years, yet not all the factors that may affect xylose fermentation performance of yeast strains are known. In this study, the mutant S. cerevisiae strain TMB 3400, which has good xylose fermentation properties, was compared with its parental strain to examine the factors behind the improved xylose utilization at protein level. The proteome of the parental and the mutant strains were characterized by difference in gel electrophoresis (DiGE) to quantitatively identify proteins that are expressed at altered levels in the mutant. The most significant changes detected by proteome analysis were the 6-10-fold increased levels of xylose reductase, xylitol dehydrogenase and transketolase (Tkl1) in the mutant, which is in accordance with previous knowledge about xylose metabolism in yeast. The level of acetaldehyde dehydrogenase (Ald6) was also significantly increased. In addition, several proteins homologous to proteins from yeast species other than S. cerevisiae were identified in both strains, demonstrating the genetic heterogeneity of industrial yeast strains. The results were also compared with a previously reported transcription analysis performed with identical experimental set-up; however, very little correlation between the two datasets was observed. The results of the proteome analysis were in good agreement with a parallel study in which rationally designed overexpression of XR, XDH and the non-oxidative pentose phosphate pathway resulted in similar improvement in xylose utilization, which demonstrates the usefulness of proteome analysis for the identification of target genes for further metabolic engineering strategies in industrial yeast strains.
酵母中的木糖发酵多年来一直是研究的目标，但并非所有可能影响酵母菌株木糖发酵性能的因素都为人所知。在本研究中，将具有良好木糖发酵特性的突变型酿酒酵母菌株TMB 3400与其亲本菌株进行比较，以在蛋白质水平上研究木糖利用改善背后的因素。通过差异凝胶电泳（DiGE）对亲本菌株和突变菌株的蛋白质组进行表征，以定量鉴定在突变体中表达水平发生变化的蛋白质。蛋白质组分析检测到的最显著变化是突变体中木糖还原酶、木糖醇脱氢酶和转酮醇酶（Tkl1）的水平增加了6至10倍，这与先前关于酵母中木糖代谢的知识一致。乙醛脱氢酶（Ald6）的水平也显著增加。此外，在两种菌株中都鉴定出了几种与酿酒酵母以外的其他酵母物种的蛋白质同源的蛋白质，这表明工业酵母菌株的遗传异质性。还将结果与之前在相同实验设置下进行的转录分析报告进行了比较；然而，在两个数据集中观察到的相关性非常小。蛋白质组分析的结果与一项平行研究非常一致，在该平行研究中，合理设计的XR、XDH和非氧化戊糖磷酸途径的过表达导致木糖利用有类似的改善，这证明了蛋白质组分析对于鉴定工业酵母菌株进一步代谢工程策略的靶基因的有用性。
