Torque-speed relationship of the flagellar motor driven by two distinct coupled ions

2015 Fiscal Year Final Research Report

• Project/Area Number: 26840035
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Functional biochemistry
• Research Institution: Osaka University
• Principal Investigator: TERAHARA Naoya 大阪大学, 生命機能研究科, 招聘研究員 (40554738)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 生体分子モーター / 1分子計測

Outline of Final Research Achievements

The rotational energy of flagellar motor is mediated by inward ion flux through the channel of the stator complexes. Bacillus subtilis has not only H+-channel MotAB but also Na+-channel MotPS as the stator. It is unknown that how the torque is generated by two distinct stators. Here, we measured the rotation speed of single motor by attaching the bead to flagellar filament under various conditions to see whether these two stators actually work together in a motor. In wild-type motors co-expressing MotAB and MotPS, the torque-speed curve was very similar to that of MotAB motors under Na+-free condition. However, the maximum speed was decreased with an increase in Na+ concentration, while the zero-speed torque was almost constant value. These observations indicate that functional incorporation of MotPS into the motor depend on the Na+ causes the speed reduction under low-load condition, but MotPS is capable of coordinately generating the torque with MotAB under high-load condition.

Free Research Field

生物物理