Understanding the relationship between xylose and the metabolic regulatory systems is a prerequisite to enhance xylose utilization in recombinant S. cerevisiae strains. Hexokinase 2 (Hxk2p) is an intracellular glucose sensor that localizes to the cytoplasm or the nucleus depending on the carbon source. Hxk2p interacts with Mig1p to regulate gene transcription in the nucleus. Here, we investigated the effect of nucleus-localized Hxk2p and Mig1p on xylose fermentation. The results show that the expression of HXK2^S14A, which encodes a constitutively nucleus-localized Hxk2p, increased the xylose consumption rate, the ethanol production rate, and the ethanol yield of the engineered yeast strain by 23.5%, 78.6% and 42.6%, respectively. The deletion of MIG1 decreased xylose utilization and eliminated the positive effect of Hxk2p. We then performed RNA-seq and found that the targets of Hxk2p^S14A on xylose were mainly genes that encode RNA-binding proteins. This is very different from the known targets of Mig1p and supports the notion that the Hxk2p-Mig1p interaction is abolished in the presence of xylose. These results will improve our understanding of the interrelation between the Snf1p-Mig1p-Hxk2p glucose signaling pathway and xylose utilization in S. cerevisiae and suggests that the expression of HXK2^S14A could be a viable strategy to improve xylose utilization.

中文翻译：

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通过表达核定位的己糖激酶2改善酿酒酵母中的木糖发酵。

了解木糖和代谢调节系统之间的关系是增强重组酿酒酵母菌株中木糖利用的先决条件。己糖激酶2（Hxk2p）是一种细胞内葡萄糖传感器，根据碳源而定位在细胞质或细胞核中。Hxk2p与Mig1p相互作用以调节细胞核中的基因转录。在这里，我们调查了核定位的Hxk2p和Mig1p对木糖发酵的影响。结果表明H XK2 ^S14A的表达编码组成性核定位的Hxk2p，使工程酵母菌株的木糖消耗率，乙醇产生率和乙醇产率分别增加了23.5％，78.6％和42.6％。MIG1的删除减少了木糖的利用，并消除了Hxk2p的积极作用。然后，我们进行了RNA测序，发现木糖上Hxk2p ^S14A的靶标主要是编码RNA结合蛋白的基因。这与Mig1p的已知目标有很大不同，并支持在木糖存在的情况下废除Hxk2p-Mig1p相互作用的概念。这些结果将增进我们对酿酒酵母中Snf1p-Mig1p-Hxk2p葡萄糖信号通路与木糖利用之间相互关系的理解。并暗示H XK2 ^S14A的表达可能是提高木糖利用率的可行策略。