Dissecting role of sucrose and GA recognition in SWEET transporters

2019 Fiscal Year Annual Research Report

• Project/Area Number: 19H00932
• Research Institution: Nagoya University
• Principal Investigator: Frommer Wolf 名古屋大学, トランスフォーマティブ生命分子研究所, 客員教授 (70795575)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: Phytohormone / Gibberellic acid / Sugar / SWEETs / Transporter

Outline of Annual Research Achievements

Transporters mediate the translocation of a large number of different solutes across cell membranes. Substrate selectivity of transporters is critical to accomplish the complex systems in biological processes involved in nutrition, signaling, or cell-cell communication. However, the molecular mechanisms of substrate selectivity of transporters have not been fully elucidated. SWEETs, which recently we identified, play essential roles through the transport activity for sucrose and/or glucose. In addition to sugars, SWEETs can transport gibberellic acid (GA), a hormone that regulates many important aspects of plant growth and development. Sugars and phytohormones are essential to the fundamental processes of plant development and growth. It has remained unclear, however, which spectrum of substrates SWEETs can transport, and how SWEETs can transport substrates. To understand the molecular mechanisms of substrate selectivity of plant transporters, we studied the substrate recognition of SWEETs using molecular docking and molecular dynamics. The docking studies have revealed residues of AtSWEET13 involved in binding GA and/or sucrose. To investigate the residues required to transport substrate, GA transporter activity assays using mammalian cells were established.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The docking studies have revealed residues of AtSWEET13 involved in binding GA and/or sucrose. To investigate the residues required to transport substrate, in-cell transporter activity assays using fluorescent probes and mammalian cells were established.

Strategy for Future Research Activity

The substrate selectivity of transporters is critical to accomplish the complex systems in biological processes. However, the molecular mechanisms of the substrate selectivity of transporters have not been fully elucidated. SWEETs play essential roles through the transport activity for sucrose and/or glucose. In addition to sugars, SWEETs can transport GA. The docking studies have revealed residues of AtSWEET13 involved in binding GA and/or sucrose. We will investigate whether residues are required to transport substrates using mammalian cells and yeast. To identify small molecules selectively inhibiting the SWEET transport activity, a screening system will be established. The screen can be performed in 96-well format with 70,000 compounds from ITbM chemical library.