Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark.
Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, DK-8000, Aarhus C, Denmark.
Nat Commun. 2019 Jan 24;10(1):407. doi: 10.1038/s41467-018-08176-9.
Plants are dependent on controlled sugar uptake for correct organ development and sugar storage, and apoplastic sugar depletion is a defense strategy against microbial infections like rust and mildew. Uptake of glucose and other monosaccharides is mediated by Sugar Transport Proteins, proton-coupled symporters from the Monosaccharide Transporter (MST) superfamily. We present the 2.4 Å structure of Arabidopsis thaliana high affinity sugar transport protein, STP10, with glucose bound. The structure explains high affinity sugar recognition and suggests a proton donor/acceptor pair that links sugar transport to proton translocation. It contains a Lid domain, conserved in all STPs, that locks the mobile transmembrane domains through a disulfide bridge, and creates a protected environment which allows efficient coupling of the proton gradient to drive sugar uptake. The STP10 structure illuminates fundamental principles of sugar transport in the MST superfamily with implications for both plant antimicrobial defense, organ development and sugar storage.
植物依赖于受控的糖分吸收来进行正确的器官发育和糖分储存，质外体糖分耗竭是抵御锈病和霉菌等微生物感染的一种防御策略。葡萄糖和其他单糖的吸收是由糖转运蛋白介导的，这些蛋白属于单糖转运蛋白（MST）超家族中的质子偶联共转运体。我们展示了拟南芥高亲和力糖转运蛋白 STP10 与葡萄糖结合的 2.4 Å 结构。该结构解释了高亲和力糖识别，并提出了一对质子供体/受体，将糖转运与质子转运联系起来。它包含一个 Lid 结构域，在所有 STP 中都保守，通过二硫键锁定可移动的跨膜结构域，并创建一个受保护的环境，使质子梯度能够有效地耦合以驱动糖吸收。STP10 的结构阐明了 MST 超家族中糖转运的基本原理，这对植物的抗菌防御、器官发育和糖分储存都有影响。
