US-Switzerland Cooperative Research on Intracellular Location of Sucrose: Sucrose Fructosyl Transferase

该奖项支持普渡大学的托马斯·霍斯利教授和尼古拉斯·卡皮塔教授与苏黎世大学的菲利普·马蒂尔教授和其他人在植物生物化学研究方面进行合作。这些科学家都对果糖和其他碳水化合物的合成和降解以及这些储存聚合物的生理作用感兴趣。他们合作的重点是研究蔗糖果糖基转移酶(SST)在小麦叶肉细胞和菊芋块茎细胞中的细胞内定位。他们假设SST与液泡膜有关，液泡膜是界定液泡的膜，并促进蔗糖向液泡的运输。此外，SST可以从液泡膜上解离，这种解离改变了SST的活性。他们计划在分离出完整的液泡后对这些假说进行经验性的检验。马蒂尔博士提供了从高等植物中分离纯净、完整的液泡的专业知识。他和他的研究小组令人信服地证明，果聚糖、SST和其他果聚糖代谢酶只存在于液泡中。霍斯利博士和卡皮塔博士提供果糖代谢和碳水化合物结构分析方面的专业知识。他们已经证明，细胞中有两个独立的蔗糖池，SST在细胞中占据一个位置，在那里它可以区分这两个池。液泡为体外研究膜结合调节酶活性提供了一种独特的系统。这项拟议的合作将使用液泡来测试果聚糖合成的模型，从而有助于深入了解原生质体和液泡中果聚糖的结合动力学。这些信息对于了解植物的初级生产力是重要的，如果我们要考虑改变植物以提高初级生产力，这些信息是必不可少的。

This award supports Professors Thomas Housley and Nicholas Carpita of Purdue University to collaborate in plant biochemistry research with Professor Philippe Matile and others of the University of Zurich. These scientists share an interest in the synthesis and degradation of fructans and other carbohydrates and the physiological role of these storage polymers. The focus of their collaboration is a study of the intracellular location of sucrose fructosyl transferase (SST) in leaf mesophyll cells of wheat and tuber cells of Jerusalem artichoke. They hypothesize that SST is associated with the tonoplast, the delimiting membrane of the vacuole, and facilitates transport of sucrose into the vacuole. Further, SST can dissociate from the tonoplast and that dissociation alters SST activity. They plan to test these hypotheses empirically after isolation of intact vacuoles. Dr. Matile offers expertise in the isolation of pure, intact vacuoles from higher plants. He and his research group have demonstrated convincingly that fructans, SST, and other enzymes of fructan metabolism were solely in the vacuole. Drs. Housley and Carpita offer expertise in fructan metabolism and carbohydrate structure analysis. They have demonstrated that there are two separate pools of sucrose in the cell, and that SST occupies a location in the cell where it can discriminate between these pools. Vacuoles provide a unique system to study in vitro the regulation of enzyme activity by membrane association. The proposed collaboration will use vacuoles to test a model of fructan synthesis and thus contribute insights into the kinetics of sugar incorporation in fructans of protoplasts and vacuoles. Such information is important for understanding primary productivity in plants, and is essential if we are to consider modifying plants to improve primary productivity.