Analysis of vacuolar sugar transport

糖在液泡中的积累对植物的发育和生理以及农艺具有重要意义。然而，目前在分子水平上尚未鉴定出相应的张力质体定位转运蛋白。我们在分子和功能水平上从拟南芥中发现了第一个液泡糖转运蛋白（TMT， tono质体单糖转运蛋白）。TMT蛋白代表了拟南芥中单糖转运蛋白的一个小亚群，包括3种亚型。所有的TMT蛋白都存在于细胞质中，并表现出独特的分子结构。Attmt1和2基因表现出组织特异性表达模式，在低温、盐胁迫和干旱胁迫或单糖胁迫下上调表达。与Wt植株相比，tmt敲除植株表现出液泡葡萄糖摄取减少和缺乏在冷诱导下积累单糖的能力。在这里，我们想扩展我们对TMT蛋白功能和调控的分析。特别是，我们对分析导致TMT蛋白的tono质体定位的结构决定因素感兴趣，我们将破译独特的大型中心环结构域的假定功能，我们将识别环结合蛋白。此外，液泡糖转运在适应低温过程中的生理影响将通过系统生物学方法得到澄清。为此，我们将比较Wt植物、tmt敲除系和tmt过表达系在冷适应过程中相应的代谢、转录组学和蛋白质组学变化。

Sugar accumulation in vacuoles is of high importance for plant development and physiology, as well as of agronomic relevance. However, corresponding tonoplast located transport proteins have not been identified on the molecular level up to now. We identified a first vacuolar sugar transporter (TMT, tonoplast monosaccharide transporter) from Arabidopsis on both, the molecular and functional level. TMT proteins represent a small subgroup of monosaccharide transporters in Arabidopsis comprising 3 isoforms. All TMT proteins reside in the tonoplast and exhibit a unique molecular structure. Attmt1 and 2 genes exhibit a tissue specific expression pattern and are up-regulated upon cold-, salt- and drought stress or monosaccharide application. tmt knock out plants show reduced vacuolar glucose uptake and lack, in contrast to Wt plants, the ability to accumulate monosaccharides upon cold induction. Here we want to extend our analysis on the function and regulation of TMT proteins. In particular, we are interested in analyzing structural determinants leading to a tonoplast localization of TMT proteins, we will decipher a putative function of the uniquely large centrally located loop domain and we will identify loop binding proteins. In addition, the physiological impact of vacuolar sugar transport during adaptation to cold temperatures will be clarified by using a systems biological approach. For this we will compare corresponding metabolic-, transcriptomic- and proteomic changes in Wt plants, in tmt knock out-, and in tmt overexpressor lines upon cold adaptation.