Measurement of proton pump activity by single molecule of VoV1

2015 Fiscal Year Final Research Report

• Project/Area Number: 26650039
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Functional biochemistry
• Research Institution: Kyoto Sangyo University
• Principal Investigator: YOKOYAMA Ken 京都産業大学, 総合生命科学部, 教授 (70271377)
• Co-Investigator(Renkei-kenkyūsha): YOKOKAWA Ryuji 京都大学, 工学研究科, 准教授 (10411216)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: V-ATPase / ATP synthase / proton pump / molecular motor / rotation

Outline of Final Research Achievements

VoV1 is a rotary molecular motor which pumps protons across the membranes coupled to ATP hydrolysis reaction in V1 portion.
In this project, we first tried to measure proton pump activity of single molecular VoV1 using micro chambers system. The estimated proton/ATP ratio (P/A ratio) is much lower than the theoretical value of 4. This might be due to a leak of proton from the micro chambers. Then we measured the P/A ratio by using a liposome system including pHrode as a pH probe in the membranes. We estimated the P/A ration of 3-4. This result suggests the energy coupling between the V1 and Vo is tight.

Free Research Field

生化学、生物物理学、構造生物学