Department of Genetics, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Hertzstrasse 16, Karlsruhe, 76187, Germany.
Molecular Plant Physiology, Friedrich Alexander University Erlangen-Nuremberg, Staudtstrasse 5, Erlangen, 91058, Germany.
New Phytol. 2015 May;206(3):1086-1100. doi: 10.1111/nph.13314. Epub 2015 Feb 10.
The smut Ustilago maydis, a ubiquitous pest of corn, is highly adapted to its host to parasitize on its organic carbon sources. We have identified a hexose transporter, Hxt1, as important for fungal development during both the saprophytic and the pathogenic stage of the fungus. Hxt1 was characterized as a high-affinity transporter for glucose, fructose, and mannose; ∆hxt1 strains show significantly reduced growth on these substrates, setting Hxt1 as the main hexose transporter during saprophytic growth. After plant infection, ∆hxt1 strains show decreased symptom development. However, expression of a Hxt1 protein with a mutation leading to constitutively active signaling in the yeast glucose sensors Snf3p and Rgt2p results in completely apathogenic strains. Fungal development is stalled immediately after plant penetration, implying a dual function of Hxt1 as transporter and sensor. As glucose sensors are only known for yeasts, 'transceptor' as Hxt1 may constitute a general mechanism for sensing of glucose in fungi. In U. maydis, Hxt1 links a nutrient-dependent environmental signal to the developmental program during pathogenic development.
玉米黑粉菌是一种普遍存在的玉米害虫，它高度适应其宿主，以寄生其有机碳源。我们已经确定了一种己糖转运蛋白 Hxt1，它在真菌的腐生和致病阶段的真菌发育中非常重要。Hxt1 被表征为对葡萄糖、果糖和甘露糖具有高亲和力的转运蛋白；∆hxt1 菌株在这些底物上的生长明显减少，这表明 Hxt1 是腐生生长过程中的主要己糖转运蛋白。在植物感染后，∆hxt1 菌株的症状发展明显减少。然而，表达一种突变导致酵母葡萄糖传感器 Snf3p 和 Rgt2p 中组成型激活信号的 Hxt1 蛋白，会导致完全无病的菌株。真菌发育在植物穿透后立即停滞，这意味着 Hxt1 具有作为转运蛋白和传感器的双重功能。由于葡萄糖传感器仅在酵母中被发现，因此 Hxt1 作为“转受体”可能构成了真菌中葡萄糖感应的一般机制。在玉米黑粉菌中，Hxt1 将营养依赖的环境信号与致病发育过程中的发育程序联系起来。
