Rapid rotation of flagellar bundles in swimming bacteria

Lowe, Graeme; Meister, Markus; Berg, Howard C.

doi:10.1038/325637a0

Cited by 234 publications

(204 citation statements)

References 21 publications

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“…The gliding speed increased linearly with temperature, as seen in bacterial flagellar motility (23). The fraction of cells bound to glass was much reduced at 36.5°C, but cells that did bind glided more rapidly.…”

Section: Discussionmentioning

confidence: 75%

Force and Velocity of Mycoplasma mobile Gliding

2002

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The effects of temperature and force on the gliding speed of Mycoplasma mobile were examined. Gliding speed increased linearly as a function of temperature from 0.46 m/s at 11.5°C to 4.0 m/s at 36.5°C. A polystyrene bead was attached to the tail of M. mobile using a polyclonal antibody raised against whole M. mobile cells. Cells attached to beads glided at the same speed as cells without beads. When liquid flow was applied in a flow chamber, cells reoriented and moved upstream with reduced speeds. Forces generated by cells at various gliding speeds were calculated by multiplying their estimated frictional drag coefficients with their velocities relative to the liquid. The gliding speed decreased linearly with force. At zero speed, the force measurements extrapolated to 26 pN at 22.5 and 27.5°C. At zero force, the speed extrapolated to 2.3 and 3.3 m/s at 22.5 and 27.5°C, respectively-the same speeds as those observed for free gliding cells. Cells attached to beads were also trapped by an optical tweezer, and the stall force was measured to be 26 to 28 pN (17.5 to 27.5°C). The gliding speed depended on temperature, but the maximum force did not, suggesting that the mechanism is composed of at least two steps, one that generates force and another that allows displacement. Other implications of these results are discussed.Mycoplasmas are parasitic bacteria with a small genome and no peptidoglycan layer (27). Several mycoplasma species have a distinct cell polarity characterized by a protruding membrane extension, the attachment organelle (27). They are able to attach to and glide on glass, plastic, and eukaryotic cell surfaces, always moving in the direction of the organelle (19). The gliding mechanism is unknown. Mycoplasmas do not have any appendages such as flagella or pili (19) or any genes obviously related to motility, including motor proteins such as myosin or kinesin (7, 10, 13). However, a transmembrane protein associated with a cytoskeleton-like structure has been shown to be necessary for glass binding in Mycoplasma pneumoniae (22).Mycoplasma mobile, isolated from a fish gill organ, has a conical cell structure, with the attachment organelle at the apex of the cone. It glides up to four cell lengths per second (2.5 m/s) in the direction of the apex, which is designated as a head-like structure (30). However, little is known about force generation (28,29). In this study, to characterize its gliding motility, we attached a bead to the tail end of M. mobile and measured the gliding force as a function of speed using viscous flow and an optical tweezer. MATERIALS AND METHODSCultivation. M. mobile strain 163K (ATCC 43663) was grown as described previously (25).Measurements of gliding speed. M. mobile cells in a culture at an optical density at 600 nm of 0.03 to 0.1 were collected by centrifugation at 10,000 ϫ g for 4 min at room temperature and resuspended in a fivefold-smaller volume of medium. A 5-l aliquot was sealed between a coverslip and a slide within a thin ring of Apiezon M grease (Apiezon Products, L...

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Section: Discussionmentioning

confidence: 75%

Force and Velocity of Mycoplasma mobile Gliding

2002

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“…600 rps in 50 mM NaCl at room temperature and increases up to ca. 1,700 rps in 300 mM NaCl at 35°C (28,29,37), whereas the speed of the proton-driven motor is 200 to 300 rps at most in S. typhimurium or E. coli (25,26).…”

Section: Vol 179 1997 Genes Of Sodium-driven Flagellar Motor 5107mentioning

confidence: 99%

Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium

et al. 1997

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The polar flagellum of Vibrio alginolyticus rotates remarkably fast (up to 1,700 revolutions per second) by using a motor driven by sodium ions. Two genes, motX and motY, for the sodium-driven flagellar motor have been identified in marine bacteria, Vibrio parahaemolyticus and V. alginolyticus. They have no similarity to the genes for proton-driven motors, motA and motB, whose products constitute a proton channel. MotX was proposed to be a component of a sodium channel. Here we identified additional sodium motor genes, pomA and pomB, in V. alginolyticus. Unexpectedly, PomA and PomB have similarities to MotA and MotB, respectively, especially in the predicted transmembrane regions. These results suggest that PomA and PomB may be sodium-conducting channel components of the sodium-driven motor and that the motor part consists of the products of at least four genes, pomA, pomB, motX, and motY. Furthermore, swimming speed was controlled by the expression level of the pomA gene, suggesting that newly synthesized PomA proteins, which are components of a force-generating unit, were successively integrated into the defective motor complexes. These findings imply that Na ؉ -driven flagellar motors may have similar structure and function as proton-driven motors, but with some interesting differences as well, and it is possible to compare and study the coupling mechanisms of the sodium and proton ion flux for the force generation.

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“…That is, the counter-rotation of the large cell is relatively slow compared with the rotational speed of the flagellum (17). [Therefore, Eqs.…”

Section: [14]mentioning

confidence: 99%

The efficiency of propulsion by a rotating flagellum

Purcell

1997

Proc. Natl. Acad. Sci. U.S.A.

325

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ABSTRACT[At very low Reynolds number, the regime in which f luid dynamics is governed by Stokes equations, a helix that translates along its axis under an external force but without an external torque will necessarily rotate. By the linearity of the Stokes equations, the same helix that is caused to rotate due to an external torque will necessarily translate. This is the physics that underlies the mechanism of f lagellar propulsion employed by many microorganisms. Here, I examine the linear relationships between forces and torques and translational and angular velocities of helical objects to understand the nature of f lagellar propulsion.]

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Rapid rotation of flagellar bundles in swimming bacteria

Cited by 234 publications

References 21 publications

Force and Velocity of Mycoplasma mobile Gliding

Force and Velocity of Mycoplasma mobile Gliding

Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium

The efficiency of propulsion by a rotating flagellum

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