Torque–speed Relationship of the Na+-driven Flagellar Motor of Vibrio alginolyticus

Sowa, Yoshiyuki; Hotta, Hiroyuki; Homma, Michio; Ishijima, Akihiko

doi:10.1016/s0022-2836(03)00176-1

Cited by 123 publications

(129 citation statements)

References 54 publications

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“…Stall torque estimates vary from 350 pN nm for Caulobacter crescentus [69], 1260 pN nm for E. coli [87] and 4000 pN nm for V. alginolyticus [95]. For comparison, we see that the computed flagellar torque shown in Table 4 for the 0.2 micron amplitude model bacterial cell converts to 5640 pN nm.…”

Section: Flagellar Parametersmentioning

confidence: 94%

“…Torque produced by the bacterial motor of E. coli show a nearly constant torque over a range of 0 to 200 Hz, depending upon temperature [14,48,49,107] and up to 300 Hz in the Na + driven motor of Vibrio alginolyticus [95]. Stall torque estimates vary from 350 pN nm for Caulobacter crescentus [69], 1260 pN nm for E. coli [87] and 4000 pN nm for V. alginolyticus [95].…”

Section: Flagellar Parametersmentioning

confidence: 99%

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A 3D Motile Rod-Shaped Monotrichous Bacterial Model

Hsu

Dillon

2009

Bull. Math. Biol.

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We introduce a 3D model for a motile rod-shaped bacterial cell with a single polar flagellum which is based on the configuration of a monotrichous type of bacteria such as Pseudomonas aeruginosa. The structure of the model bacterial cell consists of a cylindrical body together with the flagellar forces produced by the rotation of a helical flagellum. The rod-shaped cell body is composed of a set of immersed boundary points and elastic links. The helical flagellum is assumed to be rigid and modeled as a set of discrete points along the helical flagellum and flagellar hook. A set of flagellar forces are applied along this helical curve as the flagellum rotates. An additional set of torque balance forces are applied on the cell body to induce counter-rotation of the body and provide torque balance. The three dimensional Navier-Stokes equations for incompressible fluid are used to described the fluid dynamics of the coupled fluid-microorganism system using Peskin's immersed boundary method. A study of numerical convergence is presented along with simulations of a single cell and the interaction of two model cells.

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Section: Flagellar Parametersmentioning

confidence: 94%

Section: Flagellar Parametersmentioning

confidence: 99%

A 3D Motile Rod-Shaped Monotrichous Bacterial Model

Hsu

Dillon

2009

Bull. Math. Biol.

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“…2a; Methods; ref. 4), exploiting the fact that the motor of V. alginolyticus is driven by trans-membrane sodium gradients 24 . At [Na + ] = 100 mM cells swam at 40 µm s −1 on average and regularly alternated between flicks and reversals ( Fig.…”

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confidence: 99%

Bacteria can exploit a flagellar buckling instability to change direction

2013

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Bacteria swim by rotating rigid helical flagella and periodically reorienting to follow environmental cues 1,2 . Despite the crucial role of reorientations, their underlying mechanism has remained unknown for most uni-flagellated bacteria 3,4 . Here, we report that uni-flagellated bacteria turn by exploiting a finely tuned buckling instability of their hook, the 100-nm-long structure at the base of their flagellar filament 5 . Combining high-speed video microscopy and mechanical stability theory, we demonstrate that reorientations occur 10 ms after the onset of forward swimming, when the hook undergoes compression, and that the associated hydrodynamic load triggers the buckling of the hook. Reducing the load on the hook below the buckling threshold by decreasing the swimming speed results in the suppression of reorientations, consistent with the critical nature of buckling. The mechanism of turning by buckling represents one of the smallest examples in nature of a biological function stemming from controlled mechanical failure 6 and reveals a new role for flexibility in biological materials, which may inspire new microrobotic solutions in medicine and engineering 7 .Flexibility is woven into every facet of living materials. At the cellular level, flexibility allows red blood cells to squeeze through capillaries 8 and DNA to stretch and twist to compensate for variability in binding site length 9 . At the organismal level, flexibility enhances structural performance, for example by enabling animal bones and plant branches to absorb mechanical energy 10 . Flexibility also underpins a host of dynamic life functions, including locomotion, reproduction and predation, by enabling the storage and swift release of elastic energy, a mechanism used by jumping froghoppers to escape predators 11 , by plants to catapult seeds for dispersal 12 , and by aquatic invertebrates to suck in prey 13 . An extreme consequence of flexibility is the occurrence of mechanical instabilities, such as buckling and fluttering, which in engineered systems are synonymous with failure 14 , but in natural systems can serve functional purpose. The biomechanical repertoire of organisms includes mechanical instabilities over a wide range of timescales, from the millisecond snap-buckling instabilities that allow Venus flytraps 15 and humming birds 16 to capture insects to the gradual buckling responsible for the wavy edges of leaves and flowers 17 .Flexible appendages are widely used by organisms for locomotion in fluids, from the flapping of bird and bat wings 18 , to the actuation of fish fins 19 , to the bending of sperm flagella 20 . Flexibility also plays a subtle role in the locomotion of bacteria with multiple flagella (peritrichous), such as Escherichia coli, which bundles its flagella together for propulsion (a run 1 ) by exploiting the compliance of the flagellum's base 21,22 . When one or more flagella leave the bundle following a change in the direction of rotation of their motor, the torque resulting from the unbundling, or from the asso...

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“…300 Hz (18 000 rpm)4 while the BFM in Vibrio alginolyticus can rotate as fast as ca. 700 Hz (42 000 rpm),5 which is nearly triple the 15 000 rpm of a modern Formula 1 racer. Additionally, while man‐made machines suffer from energy loss due to heating, the BFM operates at near 100% efficiency of energy conversion from ion transit to motor torque 6…”

Section: Introductionmentioning

confidence: 93%

“…The rotation speed of the bead can be record by a fast camera mounted on a microscope while the viscosity of the external medium is rapidly changed by adding Ficoll,4 or while the drag coefficient of the bead is changed by varying the size of the bead 5…”

Section: Function Of the Bacterial Flagellar Motormentioning

confidence: 99%

A Delicate Nanoscale Motor Made by Nature—The Bacterial Flagellar Motor

Xue

Baker

et al. 2015

Advanced Science

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The bacterial flagellar motor (BFM) is a molecular complex ca. 45 nm in diameter that rotates the propeller that makes nearly all bacteria swim. The motor self‐assembles out of ca. 20 different proteins and can not only rotate at up to 50 000 rpm, but can also switch rotational direction in milliseconds and navigate its environment to maneuver, on average, towards regions of greater benefit. The BFM is a pinnacle of evolution that informs and inspires the design of novel nanotechnology in the new era of synthetic biology.

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Torque–speed Relationship of the Na+-driven Flagellar Motor of Vibrio alginolyticus

Cited by 123 publications

References 54 publications

A 3D Motile Rod-Shaped Monotrichous Bacterial Model

A 3D Motile Rod-Shaped Monotrichous Bacterial Model

Bacteria can exploit a flagellar buckling instability to change direction

A Delicate Nanoscale Motor Made by Nature—The Bacterial Flagellar Motor

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