scholarly journals 2SA04 Single molecule measurement of the bacterial flagellar motor

2005 ◽  
Vol 45 (supplement) ◽  
pp. S18
Author(s):  
Y. Sowa
Keyword(s):  
Single Molecule ◽  
Flagellar Motor ◽  
Bacterial Flagellar Motor

Assembly and Dynamics of the Bacterial Flagellum

2020 ◽  
Vol 74 (1) ◽  
pp. 181-200 ◽  
Author(s):  
Judith P. Armitage ◽  
Richard M. Berry
Keyword(s):  
Single Molecule ◽  
Protein Complexes ◽  
Complex Structure ◽  
Live Cells ◽  
Flagellar Motor ◽  
Interacting Protein ◽  
Bacterial Flagellum ◽  
Bacterial Flagellar Motor ◽  
The Stability

The bacterial flagellar motor is the most complex structure in the bacterial cell, driving the ion-driven rotation of the helical flagellum. The ordered expression of the regulon and the assembly of the series of interacting protein rings, spanning the inner and outer membranes to form the ∼45–50-nm protein complex, have made investigation of the structure and mechanism a major challenge since its recognition as a rotating nanomachine about 40 years ago. Painstaking molecular genetics, biochemistry, and electron microscopy revealed a tiny electric motor spinning in the bacterial membrane. Over the last decade, new single-molecule and in vivo biophysical methods have allowed investigation of the stability of this and other large protein complexes, working in their natural environment inside live cells. This has revealed that in the bacterial flagellar motor, protein molecules in both the rotor and stator exchange with freely circulating pools of spares on a timescale of minutes, even while motors are continuously rotating. This constant exchange has allowed the evolution of modified components allowing bacteria to keep swimming as the viscosity or the ion composition of the outside environment changes.

scholarly journals Bacterial flagellar motor

2008 ◽  
Vol 41 (2) ◽  
pp. 103-132 ◽  
Author(s):  
Yoshiyuki Sowa ◽  
Richard M. Berry
Keyword(s):  
Single Molecule ◽  
Cell Envelope ◽  
Molecular Motor ◽  
Motive Force ◽  
Flagellar Motor ◽  
Large Size ◽  
Structural Details ◽  
Bacterial Flagellar Motor ◽  
And Function ◽  
Rotary Motor

AbstractThe bacterial flagellar motor is a reversible rotary nano-machine, about 45 nm in diameter, embedded in the bacterial cell envelope. It is powered by the flux of H+or Na+ions across the cytoplasmic membrane driven by an electrochemical gradient, the proton-motive force or the sodium-motive force. Each motor rotates a helical filament at several hundreds of revolutions per second (hertz). In many species, the motor switches direction stochastically, with the switching rates controlled by a network of sensory and signalling proteins. The bacterial flagellar motor was confirmed as a rotary motor in the early 1970s, the first direct observation of the function of a single molecular motor. However, because of the large size and complexity of the motor, much remains to be discovered, in particular, the structural details of the torque-generating mechanism. This review outlines what has been learned about the structure and function of the motor using a combination of genetics, single-molecule and biophysical techniques, with a focus on recent results and single-molecule techniques.

scholarly journals The Architectural Dynamics of the Bacterial Flagellar Motor Switch

Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 833
Author(s):  
Shahid Khan
Keyword(s):  
Single Molecule ◽  
Protein Interactions ◽  
Cell Biophysics ◽  
Flagellar Motor ◽  
Research Strategies ◽  
The Core ◽  
Switch Operation ◽  
Flagellar Filament ◽  
Bacterial Flagellar Motor ◽  
New Research

The rotary bacterial flagellar motor is remarkable in biochemistry for its highly synchronized operation and amplification during switching of rotation sense. The motor is part of the flagellar basal body, a complex multi-protein assembly. Sensory and energy transduction depends on a core of six proteins that are adapted in different species to adjust torque and produce diverse switches. Motor response to chemotactic and environmental stimuli is driven by interactions of the core with small signal proteins. The initial protein interactions are propagated across a multi-subunit cytoplasmic ring to switch torque. Torque reversal triggers structural transitions in the flagellar filament to change motile behavior. Subtle variations in the core components invert or block switch operation. The mechanics of the flagellar switch have been studied with multiple approaches, from protein dynamics to single molecule and cell biophysics. The architecture, driven by recent advances in electron cryo-microscopy, is available for several species. Computational methods have correlated structure with genetic and biochemical databases. The design principles underlying the basis of switch ultra-sensitivity and its dependence on motor torque remain elusive, but tantalizing clues have emerged. This review aims to consolidate recent knowledge into a unified platform that can inspire new research strategies.

scholarly journals Theories of rotary motors

2000 ◽  
Vol 355 (1396) ◽  
pp. 503-509 ◽  
Author(s):  
Richard M. Berry
Keyword(s):  
Single Molecule ◽  
Structural Data ◽  
Geometric Constraints ◽  
Flagellar Motor ◽  
Motor Behaviour ◽  
Electrochemical Gradient ◽  
Rotary Motors ◽  
Bacterial Flagellar Motor ◽  
Near Future ◽  
Turbine Model

The bacterial flagellar motor and the ATP–hydrolysing F 1 portion of the F 1 F o –ATPase are known to be rotary motors, and it seems highly probable that the H + –translocating F o portion rotates too. The energy source in the case of F o and the flagellar motor is the flow of ions, either H + (protons) or Na + , down an electrochemical gradient across a membrane. The fact that ions flow in a particular direction through a well–defined structure in these motors invites the possibility of a type of mechanism based on geometric constraints between the rotor position and the paths of ions flowing through the motor. The two beststudied examples of such a mechanism are the ‘turnstile’ model of Khan and Berg and the ‘proton turbine’ model of Lauger or Berry. Models such as these are typically represented by a small number of kinetic states and certain allowed transitions between them. This allows the calculation of predictions of motor behaviour and establishes a dialogue between models and experimental results. In the near future structural data and observations of single–molecule events should help to determine the nature of the mechanism of rotary motors, while motor models must be developed that can adequately explain the measured relationships between torque and speed in the flagellar motor.

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