Vacuoles release sucrose via tonoplast-localised SUC4-type transporters.
Vacuoles release sucrose via tonoplast-localised SUC4-type transporters.
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DOI：
10.1111/j.1438-8677.2011.00506.x
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发表时间：
2012-03
期刊：
影响因子：
3.9
通讯作者：
Sabine Schneider;S. Hulpke;S. Hulpke;Alexander Schulz;I. Yaron;J. Höll;Astrid Imlau;B. Schmitt-B.-Schm
中科院分区：
文献类型：
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作者：
Sabine Schneider;S. Hulpke;S. Hulpke;Alexander Schulz;I. Yaron;J. Höll;Astrid Imlau;B. Schmitt-B.-Schm
拟南芥有七个功能活跃的蔗糖转运蛋白基因。与其他双子叶和单子叶植物的蔗糖转运蛋白一起，这些蛋白质形成了四个独立的系统发育类群。第四类包括拟南芥蛋白SUC4(同名SUT4)以及来自单子叶和双子叶植物的相关蛋白。这些第四类蔗糖转运蛋白被报道为液泡膜或质膜转运蛋白，在异源表达系统中被证明是蔗糖/H(+)转运蛋白。在这里，我们对拟南芥SUC4蛋白和其他几种第四类蔗糖转运蛋白的亚细胞定位进行了比较分析，对拟南芥SUC4启动子的组织特异性进行了研究，对Atsu4.1突变体和AtSUC4过度表达(AtSUC4-ox)植物的表型特征进行了研究，并对Atsu4.1和AtSUC4-ox空泡的功能进行了比较。我们的数据显示，来自不同植物家族(十字花科、葫芦科和茄科)的SUC4型蔗糖转运蛋白仅定位于液泡膜，表明液泡蔗糖转运蛋白是所有SUC4型蛋白的共同主题。AtSUC4的表达仅限于拟南芥根的中柱、发育中的花药和所有地上部分的分生组织。对WT和突变体幼苗的碳水化合物含量的分析表明，AtSUC4-OX幼苗的蔗糖含量降低。这与对AtSUC4-ox空泡的膜片钳分析相一致，该分析表明AtSUC4是液泡膜上直接的蔗糖/H(+)转运体。
Arabidopsis thaliana has seven genes for functionally active sucrose transporters. Together with sucrose transporters from other dicot and monocot plants, these proteins form four separate phylogenetic groups. Group-IV includes the Arabidopsis protein SUC4 (synonym SUT4) and related proteins from monocots and dicots. These Group-IV sucrose transporters were reported to be either tonoplast- or plasma membrane-localised, and in heterologous expression systems were shown to act as sucrose/H(+) symporters. Here, we present comparative analyses of the subcellular localisation of the Arabidopsis SUC4 protein and of several other Group-IV sucrose transporters, studies on tissue specificity of the Arabidopsis SUC4 promoter, phenotypic characterisations of Atsuc4.1 mutants and AtSUC4 overexpressing (AtSUC4-OX) plants, and functional comparisons of Atsuc4.1 and AtSUC4-OX vacuoles. Our data show that SUC4-type sucrose transporters from different plant families (Brassicaceae, Cucurbitaceae and Solanaceae) localise exclusively to the tonoplast, demonstrating that vacuolar sucrose transport is a common theme of all SUC4-type proteins. AtSUC4 expression is confined to the stele of Arabidopsis roots, developing anthers and meristematic tissues in all aerial parts. Analyses of the carbohydrate content of WT and mutant seedlings revealed reduced sucrose content in AtSUC4-OX seedlings. This is in line with patch-clamp analyses of AtSUC4-OX vacuoles that characterise AtSUC4 as a sucrose/H(+) symporter directly in the tonoplast membrane.