AtSWEET13 糖转运蛋白底物识别和转运的分子机制。
Molecular mechanism of substrate recognition and transport by the AtSWEET13 sugar transporter.
机构信息
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
出版信息
Proc Natl Acad Sci U S A. 2017 Sep 19;114(38):10089-10094. doi: 10.1073/pnas.1709241114. Epub 2017 Sep 6.
Sugar Will Eventually be Exported Transporters (SWEETs) are recently identified sugar transporters that can discriminate and transport di- or monosaccharides across a membrane following the concentration gradient. SWEETs play key roles in plant biological processes, such as pollen nutrition, nectar secretion, seed filling, and phloem loading. SWEET13 from (AtSWEET13) is an important sucrose transporter in pollen development. Here, we report the 2.8-Å resolution crystal structure of AtSWEET13 in the inward-facing conformation with a substrate analog, 2'-deoxycytidine 5'-monophosphate, bound in the central cavity. In addition, based on the results of an in-cell transport activity assay and single-molecule Förster resonance energy transfer analysis, we suggest a mechanism for substrate selectivity based on the size of the substrate-binding pocket. Furthermore, AtSWEET13 appears to form a higher order structure presumably related to its function.
糖将最终被出口转运蛋白（SWEETs）是最近发现的糖转运蛋白，能够在浓度梯度下识别和跨膜运输二糖或单糖。SWEETs 在植物的生物过程中发挥着关键作用，如花粉营养、花蜜分泌、种子填充和韧皮部装载。来自拟南芥的 SWEET13（AtSWEET13）是花粉发育中重要的蔗糖转运蛋白。在这里，我们报告了 AtSWEET13 以内向构象的 2.8Å 分辨率晶体结构，其中中央腔结合了一个底物类似物 2'-脱氧胞苷 5'-单磷酸。此外，基于细胞内转运活性测定和单分子Förster 共振能量转移分析的结果，我们提出了一种基于底物结合口袋大小的底物选择性机制。此外，AtSWEET13 似乎形成了一种更高阶的结构，这可能与其功能有关。
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