Structural Basis for drug transport by ABC transporters

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07306
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural biochemistry
• Research Institution: Kyoto University
• Principal Investigator: Kodan Atsushi 京都大学, 高等研究院, 特定助教 (80360543)
• Co-Investigator(Kenkyū-buntansha): HIPOLITO CHRIS 筑波大学, 医学医療系, 助教 (20759914)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: ABC輸送体 / P糖蛋白質 / 膜蛋白質 / 分子メカニズム / 機能-構造相関 / ATP

Outline of Final Research Achievements

P-glycoprotein, a member of the ATP-binding cassette (ABC) transporter family, extrudes a large variety of lipophilic compounds from cells, but the underlying molecular mechanism of how the transporter performs multidrug pumping using ATP as fuel remains unknown. We have solved two structures of a eukaryotic P-glycoprotein ortholog: an outward-open state with bound nucleotide, and an inward-open state. The detailed structural differences between the two conformations of the same molecule allowed us to propose a rational model for the molecular mechanism. To evaluate the validity of the model, we generated more than 100 mutants and test their functions by biochemical analyses. These results supported the validity of the proposed model, indicating that this transporter squeezes various lipophilic compounds to the extracellular space and that the squeeze movement is driven by local conformational changes of nucleotide binding domains upon ATP binding.

Free Research Field

細胞生化学　分子生物学　蛋白質工学　構造機能生物学

Academic Significance and Societal Importance of the Research Achievements

これまでに異なる二状態（内向型と外向型）の結晶構造を同一のP糖蛋白質で明らかにした例はなかった。代表者らは、ヒトP糖蛋白質と基質特性が良く似たP糖蛋白質オーソログを見いだし、その両状態の結晶構造を世界に先駆けて高分解能で決定することに成功した。両者の原子レベルでの厳密な比較、および、機能-構造相関解析により、当輸送体の分子メカニズムの理解を飛躍的に向上させることに成功した。本研究で得られた成果は、ABC蛋白質全般の機能を考える上で重要であり、新たな治療方針や創薬アイデアの策定に多大な貢献ができると期待される。