Development of novel biosensor probes capable of sensing dynamic changes in intracellular sodium ion concentration

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19274
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 43:Biology at molecular to cellular levels, and related fields
• Research Institution: Osaka University
• Principal Investigator: Minamino Tohru 大阪大学, 大学院生命機能研究科, 准教授 (20402993)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 細菌 / 蛋白質 / 遺伝学 / 感染症

Outline of Final Research Achievements

The MotPS complex acts as a sodium ion-driven stator unit in the Bacillus subtilis flagellar motor and binds to the peptidoglycan layer via the peptidoglycan-binding domain of MotS (MotS-PGB) to become an active stator unit. When the external sodium ion concentration exceeds about 130 mM, sodium ions bind directly to MotS-PGB and induce the disorder-to-order transition of MotS-PGB. When sodium ions are depleted, MotS-PGB becomes unstructured, causing rapid dissociation of the MotPS complex from the motor. Such conformational changes of MotS-PGB autonomously regulates the number of active stator units around the flagellar motor. In this study, we show that the Asp-70 and Glu-76 residues of MotS are sodium ion binding sites and that the region from Gln-68 to Glu-117 of MotS undergoes a reversible conformational change in the presence of sodium ions.

Free Research Field

分子微生物学、生物物理学、生化学

Academic Significance and Societal Importance of the Research Achievements

従来の蛍光色素を用いた細胞内ナトリウムイオン濃度の動的時間変化の測定は、定量的な解析が困難であるとともに、蛍光色素による細胞毒性が大きな問題となっている。本研究で同定したナトリウムセンサーはナトリウムイオンの濃度変化に迅速に応答できる非侵襲性バイオセンサープローブの開発に利用できる。このようなバイオセンサープローブは様々な生物種の細胞に発現させることができるため、ナトリウムイオンが関与する様々な生命現象の解明に貢献することが期待される。