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We have developed a new technique for measurements of piconewton forces and nanometer displacements in the millisecond time range caused by actin-myosin interaction in vitro by manipulating single actin filaments with a glass microneedle. Here, we describe in full the details of this method. Using this method, the elementary events in energy transduction by(More)
The bacterial flagellar motor is a rotary molecular machine that rotates the helical filaments that propel many species of swimming bacteria. The rotor is a set of rings up to 45 nm in diameter in the cytoplasmic membrane; the stator contains about ten torque-generating units anchored to the cell wall at the perimeter of the rotor. The free-energy source(More)
We have developed a technique that allows mechanical and ligand-binding events in a single myosin molecule to be monitored simultaneously. We describe how steps in the ATPase reaction are temporally related to mechanical events at the single molecule level. The results show that the force generation does not always coincide with the release of bound(More)
A new system has been developed for measuring the forces produced by a small number (less than 5-150) of myosin molecules interacting with a single actin filament in vitro. The technique can resolve forces of less than a piconewton and has a time resolution in the submillisecond range. It can thus detect fluctuations of force caused by individual molecular(More)
The bacterial flagellar motor is a rotary motor driven by the electrochemical potential of a coupling ion. The interaction between a rotor and stator units is thought to generate torque. The overall structure of flagellar motor has been thought to be static, however, it was recently proved that stators are exchanged in a rotating motor. Understanding the(More)
The torque-speed relationship of the Na(+)-driven flagellar motor of Vibrio alginolyticus was investigated. The rotation rate of the motor was measured by following the position of a bead, attached to a flagellar filament, using optical nanometry. In the presence of 50mM NaCl, the generated torque was relatively constant ( approximately 3800pNnm) at lower(More)
The bacterial flagellar motor is a rotary motor in the cell envelope of bacteria that couples ion flow across the cytoplasmic membrane to torque generation by independent stators anchored to the cell wall. The recent observation of stepwise rotation of a Na(+)-driven chimeric motor in Escherichia coli promises to reveal the mechanism of the motor in(More)
Resolving single fluorescent molecules in the presence of high fluorophore concentrations remains a challenge in single-molecule biophysics that limits our understanding of weak molecular interactions. Total internal reflection fluorescence (TIRF) imaging, the workhorse of single-molecule fluorescence microscopy, enables experiments at concentrations up to(More)
The bacterial flagellar motor is driven by the electrochemical potential of specific ions, H(+) or Na(+). The motor consists of a rotor and stator, and their interaction generates rotation. The stator, which is composed of PomA and PomB in the Na(+) motor of Vibrio alginolyticus, is thought to be a torque generator converting the energy of ion flux into(More)
An Escherichia coli cell transduces extracellular stimuli sensed by chemoreceptors to the state of an intracellular signal molecule, which regulates the switching of the rotational direction of the flagellar motors from counterclockwise (CCW) to clockwise (CW) and from CW back to CCW. Here, we performed high-speed imaging of flagellar motor rotation and(More)