一种真菌木糖异构酶的高水平功能表达：酿酒酵母高效发酵木糖产乙醇的关键？
High-level functional expression of a fungal xylose isomerase: the key to efficient ethanolic fermentation of xylose by Saccharomyces cerevisiae?
作者信息
Kuyper Marko, Harhangi Harry R, Stave Ann Kristin, Winkler Aaron A, Jetten Mike S M, de Laat Wim T A M, den Ridder Jan J J, Op den Camp Huub J M, van Dijken Johannes P, Pronk Jack T
机构信息
Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
出版信息
FEMS Yeast Res. 2003 Oct;4(1):69-78. doi: 10.1016/S1567-1356(03)00141-7.
Evidence is presented that xylose metabolism in the anaerobic cellulolytic fungus Piromyces sp. E2 proceeds via a xylose isomerase rather than via the xylose reductase/xylitol-dehydrogenase pathway found in xylose-metabolising yeasts. The XylA gene encoding the Piromyces xylose isomerase was functionally expressed in Saccharomyces cerevisiae. Heterologous isomerase activities in cell extracts, assayed at 30 degrees C, were 0.3-1.1 micromol min(-1) (mg protein)(-1), with a Km for xylose of 20 mM. The engineered S. cerevisiae strain grew very slowly on xylose. It co-consumed xylose in aerobic and anaerobic glucose-limited chemostat cultures at rates of 0.33 and 0.73 mmol (g biomass)(-1) h(-1), respectively.
有证据表明，厌氧纤维素分解真菌皮罗霉菌E2中的木糖代谢是通过木糖异构酶进行的，而不是通过木糖代谢酵母中发现的木糖还原酶/木糖醇脱氢酶途径。编码皮罗霉菌木糖异构酶的XylA基因在酿酒酵母中实现了功能表达。在30℃下测定，细胞提取物中的异源异构酶活性为0.3 - 1.1微摩尔·分钟⁻¹·（毫克蛋白质）⁻¹，木糖的Km值为20 mM。工程化的酿酒酵母菌株在木糖上生长非常缓慢。在需氧和厌氧葡萄糖限制恒化器培养中，它分别以0.33和0.73毫摩尔·（克生物量）⁻¹·小时⁻¹的速率共同消耗木糖。
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