Torulaspora delbrueckii is a yeast species receiving increasing attention from the biotechnology industry, with particular relevance in the wine, beer and baking sectors. However, little is known about its sugar transporters and sugar transport capacity, frequently a rate-limiting step of sugar metabolism and efficient fermentation. Actually, only one glucose transporter, Lgt1, has been characterized so far. Here we report the identification and characterization of a second glucose transporter gene, IGT1, located in a cluster, upstream of LGT1 and downstream of two other putative hexose transporters. Functional characterization of IGT1 in a Saccharomyces cerevisiae hxt-null strain revealed that it encodes a transporter able to mediate uptake of glucose, fructose and mannose and established that its affinity, as measured by Km, could be modulated by glucose concentration in the medium. In fact, IGT1-transformed S. cerevisiae hxt-null cells, grown in 0.1% glucose displayed biphasic glucose uptake kinetics with an intermediate- (Km = 6.5 ± 2.0 mM) and a high-affinity (Km = 0.10 ± 0.01 mM) component, whereas cells grown in 2% glucose displayed monophasic kinetics with an intermediate-affinity (Km of 11.5 ± 1.5 mM). This work contributes to a better characterization of glucose transport in T. delbrueckii, with relevant implications for its exploitation in the food industry.

中文翻译：

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Torulaspora delbrueckii中的己糖转运：鉴定新型双亲和力转运蛋白Igt1。

Torulaspora delbrueckii是一种酵母，受到了生物技术行业的越来越多的关注，特别是在葡萄酒，啤酒和烘焙领域。但是，人们对其糖转运蛋白和糖转运能力知之甚少，常常是糖代谢和高效发酵的限速步骤。实际上，到目前为止，仅表征了一种葡萄糖转运蛋白Lgt1。在这里，我们报告第二个葡萄糖转运蛋白基因IGT1的鉴定和表征，该基因位于LGT1上游和另外两个假定的己糖转运蛋白下游的簇中。酿酒酵母hxt-null菌株中IGT1的功能表征表明，它编码一种能够介导葡萄糖，果糖和甘露糖摄取的转运蛋白，并确定了其亲和力（以Km进行测量）可以通过培养基中的葡萄糖浓度来调节。事实上，在0.1％葡萄糖中生长的IGT1转化的酿酒酵母hxt-null细胞显示出双相葡萄糖摄取动力学，具有中等（Km = 6.5±2.0 mM）和高亲和力（Km = 0.10±0.01 mM）成分，而在2％葡萄糖中生长的细胞则表现出单相动力学，具有中等亲和力（Km为11.5±1.5 mM）。这项工作有助于更好地表征T. delbrueckii中的葡萄糖转运，对其在食品工业中的开发具有重要意义。而在2％葡萄糖中生长的细胞则表现出单相动力学，具有中等亲和力（Km为11.5±1.5 mM）。这项工作有助于更好地表征T. delbrueckii中的葡萄糖转运，对其在食品工业中的开发具有重要意义。而在2％葡萄糖中生长的细胞则表现出单相动力学，具有中等亲和力（Km为11.5±1.5 mM）。这项工作有助于更好地表征T. delbrueckii中的葡萄糖转运，对其在食品工业中的开发具有重要意义。