The Hidden Role of the Multidrug Efflux Pump: Understanding Its Role by Identifying Its Unknown Substrates

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15994
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 47030:Pharmaceutical hygiene and biochemistry-related
• Research Institution: Hiroshima University
• Principal Investigator: Morita Daichi 広島大学, 医系科学研究科(薬), 助教 (80826371)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 多剤排出ポンプ / 黄色ブドウ球菌 / メタボローム / 反転膜

Outline of Final Research Achievements

The multidrug efflux pump is the most basic defense system innate to all bacteria. However, since many homologues do not transport antimicrobials and antimicrobials are artifacts, the true role of multidrug efflux pumps is unknown. This study explored the original substrates transported by the major multidrug efflux pump of Staphylococcus aureus.
Disruption of the three major pumps (norA, mdeA, and mepA), which are constitutively expressed in Staphylococcus aureus, did not affect growth, but decreased the intracellular metabolites, mainly TCA cycle and amino acids. In addition, the possibility of substrate enrichment by inverted membrane vesicles was investigated by detecting norfloxacin, a substrate of norA, within the inverted membrane vesicles.

Free Research Field

薬学

Academic Significance and Societal Importance of the Research Achievements

多剤排出ポンプは薬剤耐性を中心とした研究が行われ、その生理的な役割は不明であった。本研究で黄色ブドウ球菌の恒常的に発現している3つの主要な多剤排出ポンプ（norA, mdeA, mepA）の破壊は、TCAサイクルやアミノ酸を中心とした細胞内代謝物の減少を引き起こし、恒常的に発現する主要な多剤排出ポンプの存在はプロトン駆動力の維持などによる細胞内恒常性安定に関与している可能性が示唆された。また反転膜小胞による基質濃縮によって反転膜小胞を利用した本来の基質探索の可能性が開かれた。