Measurement of protein translocation by SecA ATPase

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K19226
• 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: Nara Institute of Science and Technology
• Principal Investigator: Tsukazaki Tomoya 奈良先端科学技術大学院大学, 先端科学技術研究科, 教授 (80436716)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 膜タンパク質

Outline of Final Research Achievements

In eubacteria, the Sec translocon complex consisting of membrane proteins SecY, SecE, and SecG (SecYEG) functions as a passive channel for membrane protein translocation from the cytoplasm to the periplasm. A motor SecA ATPase for the protein translocation pushes pre-proteins into the SecYEG. The detailed dynamics of how the conformational change of SecA ATPase functions in concert with protein translocation is unclear. In this study, we attempted to visualize the structural dynamics of the SecYEG-SecA complex in protein translocation using high-speed atomic force microscopy. We were able to observe the binding of unfolded substrate proteins to the SecYAEG complex reconstituted into nanodiscs and the transport of the substrate proteins in real-time. In addition, nucleotide-dependent conformational changes of a domain of the SecA ATPase were visualized.

Free Research Field

Structural Life Science

Academic Significance and Societal Importance of the Research Achievements

本研究は未だ可視化されていないSecタンパク質によるタンパク質の膜透過のダイナミクスを明らかとすべく研究を進めた。世界で初めてタンパク質輸送をリアルタイムで捉えることができた。今後は、この結果をまとめて原著論文として発表する。本解析は、機能解析が進んでいない他の膜タンパク質にも利用できるため、新しいことを発見した学術的意義だけでなく、膜タンパク質の解析法の一つとして技術的な貢献がある。