Molecular identification and physiological characterization of a novel monosaccharide transporter from Arabidopsis involved in vacuolar sugar transport
Molecular identification and physiological characterization of a novel monosaccharide transporter from Arabidopsis involved in vacuolar sugar transport
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DOI：
10.1105/tpc.106.047290
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发表时间：
2006-12-01
期刊：
影响因子：
11.6
通讯作者：
Neuhaus, H. Ekkehard
中科院分区：
文献类型：
--
作者：
Wormit, Alexandra;Trentmann, Oliver;Neuhaus, H. Ekkehard
拟南芥细胞质单糖转运蛋白（TMT）家族包括三个亚型，TMT-绿色荧光蛋白融合蛋白靶向液泡膜。TMT启动子-b-葡萄糖醛酸酶植物发现，TONOPLAST单糖转运蛋白1 （TMT1）和TMT2基因表现出组织和细胞类型特异性表达模式，而TMT3仅弱表达。TMT1和TMT2的表达受干旱、盐、冷处理和糖的诱导。在冷适应过程中，与野生型植物相比，tmt基因敲除系积累的葡萄糖和果糖较少，而蔗糖则没有差异。野生型植物的冷适应极大地促进了离体叶肉液泡对葡萄糖的吸收。葡萄糖被NH4+、果糖和根际菌素所抑制，这表明葡萄糖的运输是能量依赖的，葡萄糖和果糖都被同一载体所吸收。两个冷诱导的tmt1基因敲除系或三次敲除植株的液泡中葡萄糖的输入量明显低于相应的野生型液泡。与野生型植物相比，tmt1基因敲除系的叶片中单糖对糖的反应最强，这表明tmt1是细胞质内葡萄糖稳态所必需的。我们的研究结果表明TMT1参与液泡单糖运输，并在应激反应中起主要作用。
The tonoplast monosaccharide transporter (TMT) family comprises three isoforms in Arabidopsis thaliana, and TMT-green fluorescent protein fusion proteins are targeted to the vacuolar membrane. TMT promoter-b-glucuronidase plants revealed that the TONOPLAST MONOSACCHARIDE TRANSPORTER1 (TMT1) and TMT2 genes exhibit a tissue-and cell type-specific expression pattern, whereas TMT3 is only weakly expressed. TMT1 and TMT2 expression is induced by drought, salt, and cold treatments and by sugar. During cold adaptation, tmt knockout lines accumulated less glucose and fructose compared with wild-type plants, whereas no differences were observed for sucrose. Cold adaptation of wild-type plants substantially promoted glucose uptake into isolated leaf mesophyll vacuoles. Glucose uptake into isolated vacuoles was inhibited by NH4+,fructose, and phlorizin, indicating that transport is energy-dependent and that both glucose and fructose were taken up by the same carrier. Glucose import into vacuoles from two cold-induced tmt1 knockout lines or from triple knockout plants was substantially lower than into corresponding wild-type vacuoles. Monosaccharide feeding into leaf discs revealed the strongest response to sugar in tmt1 knockout lines compared with wild-type plants, suggesting that TMT1 is required for cytosolic glucose homeostasis. Our results indicate that TMT1 is involved in vacuolar monosaccharide transport and plays a major role during stress responses.