Molecular mechanism of substrate recognition and transport by the AtSWEET13 sugar transporter, PNAS, Vol. 114, No 38, pp. 10089–10094, 19 Sep 2017

PNAS, Vol. 114, No 38, pp. 10089–10094, 19 Sep 2017, DOI: 10.1073/pnas.1709241114

Molecular mechanism of substrate recognition and transport by the AtSWEET13 sugar transporter

Lei Han, Yongping Zhu, Min Liu, Ye Zhou, Guangyuan Lu, Lan Lan, Xianping Wang, Yongfang Zhao, and Xuejun C. Zhang

Abstract

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 Arabidopsis thaliana (AtSWEET13) is an important sucrose transporter in pollen development. Here, we report the 2.8-angstrom 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 Forster 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.

文章链接：http://www.pnas.org/content/114/38/10089.abstract