研究期間：10108~10207;The aim of this project is to understand the dynamics of the bacterial flagellar motor. Many species of bacteria can swim by means of the flagella and the bacterial flagellar motors (BFM). These external flagella are passive propeller. The main power sources are the BFM embedded on the cell membrane. BFM are 45 nm wide electrical motors and can rotate up to one hundred thousand rpm and propel the cell up the tenth of microns per second. BFM are the most powerful natural molecular motor we have found. In our first NSC project, we have built a Molecular Motor Biophysics Lab and combine optical nanometry, optical tweezer, fluorescent microscopy and biochemistry technique to measure the rotation, sodium motive force and sodium flux of the BFM. We measured the torque-speed relationship, single motor ion flux and the stepping behavior. We also found that the BFM is dynamical in the energetic and proteinic respects. We would like to extend our understanding to the dynamical level by using super-resolution fluorescent microscopy and ultrafast high-sensitivity camera. We would like to build up a new experimental system to explore the stator dynamics in the functional motor, single motor flux in different load/switching/stator conditions, stator energetical stability and multi-motor switching correlation under load. The super-resolution experiments can be achieved by using Photo-activation localization microscopy (PALM) to determine the stator location and dynamics. We will add optical tweezer/magnetic tweezer to control the rotation of the BFM while we are monitoring the intracellular sodium concentration to measure the ion flux. We will combine an ultrafast camera in the optical tweezer system to monitor multimotor rotation simultaneously. We are going to use these new techniques to explore the dynamical properties of the functional molecular motor. Recent experiments of BFM show that the cells have multiple control of the motor function such as switching and stopping. Some proteins of the BFM are dynamically exchange with external pool in the membrane. It’s very different from our naïve thinking of a stable macroscopic motor. These dynamical processes may be the reason of high efficiency and flexibility of molecular motor. We can’t build artificial active mechanical components in the nanoscale by our current technology. We believe that the research and understanding of these natural high performance bacterial flagellar motor can provide the new physical insight and technological breakthrough in the micro-scale world.
