Dynamic stiffening of the flagellar hook

Nord, Ashley L.; Biquet-Bisquert, Anais; Abkarian, Manouk; Pigaglio, Théo; Seduk, Farida; Magalon, Axel; Pedaci, Francesco

doi:10.1038/s41467-022-30295-7

Cited by 12 publications

(12 citation statements)

References 56 publications

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“…The noise due to detection precision and hook flexing could be extracted from the radial fluctuation of the bead trajectory. According to a recent work, [20] from the radial fluctuation of the bead positions shown in Fig. 3(d), and the characteristic time of hook bending, we could extract the average angle of inclination θ as shown in Fig.…”

Section: Other Sources Of Noisementioning

confidence: 99%

“…We choose 0.1 s as the lower limit because the characteristic time of the fluctuation due to the hook flexing can be up to ∼ 0.01 s when the stator number is 1. [20] From the linear fitting with Eq. ( 6), D tot and thus D N could be extracted from the slope, and then τ N could be extracted from the intercept at ∆t = 0 s. For example, for the data shown in Fig.…”

Section: Fluctuation Of the Motor Torquementioning

confidence: 99%

“…However, we found that there exists an extra ultrafast fluctuation that overwhelms the thermal fluctuation. By eliminating var-ious types of experimental noises, [19,20] we characterized the timescale and amplitude of this unknown fluctuation, finding that it was probably due to stepping in the motor rotation. [21,22] 2.…”

Section: Introductionmentioning

confidence: 99%

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Stochastic fluctuations in the rotation of the bacterial flagellar motor

2023

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The bacterial flagellar motor is a nanometer-sized rotary motor that generates the torque to drive the rotation of the flagellar filament. The output torque is an important property of the motor. The motor rotation was usually monitored by attaching a μm-sized bead to a shortened flagellar filament, and the torque was extracted by calculating the torque due to the viscous drag of the medium on the bead rotation. We sought for an independent extraction of the torque from thermal fluctuation in the motor rotation using the fluctuation theorem (FT). However, we identified an overwhelming fluctuation beyond the thermal noise that precluded the use of FT. We further characterized the timescale and the amplitude of this fluctuation, finding that it was probably due to the stepping of the motor. The amplitude of torque fluctuation we characterized here provided new information on the torque-generating interaction potential curve.

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Section: Other Sources Of Noisementioning

confidence: 99%

Section: Fluctuation Of the Motor Torquementioning

confidence: 99%

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Stochastic fluctuations in the rotation of the bacterial flagellar motor

2023

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“…Our measurements were based on a modification of the BFM bead assay, typically employed to study the dynamics of the motor [24,35]. We measured the BFM angular speed via bright field microscopy (with up to a 20 kHz sampling rate [36]) by tracking the recorded holograms of the off-axis rotation of 600 nm-diameter beads attached to flagellar stubs of individual immobilized E. coli cells (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal dynamics of the proton motive force on single bacterial cells

Biquet-Bisquert

Carrio

Meyer

et al. 2023

Preprint

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Electrochemical gradients established across biological membranes are fundamental in the bioenergetics of all forms of life. In bacteria, the proton motive force (PMF), the electrochemical potential associated to protons, powers an impressive array of fundamental processes, from ATP production to motility. While far from equilibrium, it has classically been considered homeostatic in time and space. Yet, recent experiments have revealed rich temporal dynamics at the single cell level and functional spatial dynamics at the scale of multicellular communities. Lateral segregation of supramolecular respiratory complexes begs the question of whether spatial heterogeneity of the PMF exists even at the single cell level. By using a light-activated proton pump as a spatially and temporally modulatable source, and the bacterial flagellar motor as a local electro-mechanical gauge, we both perturb and probe the PMF on single cells. Using global perturbations, we resolve temporal dynamics on the ms time scale and observe an asymmetrical capacitive response of the cell. Using localized perturbations, we find that the PMF is rapidly homogenized along the entire cell, faster than proton diffusion can allow. Instead, the electrical response can be explained in terms of electrotonic potential spread, as found in passive neurons and described by cable theory. This implies a global coupling between PMF sources and consumers in the bacterial membrane, excluding a sustained spatial heterogeneity while allowing for fast temporal dynamics.

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“…Due to the compliance of the agellar hook that connects the motor to the lament, the bead is normally not rotating inside only one imaging plane. Due to limitations in the axial resolution for typical 3D tracking methods such as defocusing or holography, 3D tracking of the bead rotation was not performed previously, and only the 2D projection of the bead trajectory was recorded 19,20 , resulting in loss of important information on the motor dynamics. Here, we demonstrated the direct measurement of the 3D trajectory of the bead rotation with high spatiotemporal resolution.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional single-particle tracking by interferometric scattering microscopy with a double-helix point spread function

Zhang

Huang²,

chen³

et al. 2023

Preprint

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Single-particle tracking (SPT) is an immensely valuable technique to study a variety of processes in the life sciences and condensed matter physics. Interferometric scattering (iSCAT) microscopy is a sensitive SPT technique that can track individual unlabeled particles with high spatial and temporal resolution. A difficulty in iSCAT is the low imaging contrast of its original image, and complicated imaging postprocessing method is necessary for deriving axial-location of the particle. Here, a planar photonic chip enhanced spin-to-orbital angular momentum conversion was introduced to the iSCAT microscopy, resulting in an axial-localization dependent double-helix point-spread-function (PSF) and high imaging contrast. This provides a new mechanism for 3D SPT over an extended axial-range in a label-free manner without use of complicated image postprocessing and optical components. The iSCAT microscopy was used to record the 3D trajectory of microbead labeled to the flagellum, facilitating precise analysis of the fluctuation in the motor dynamics. The enhanced iSCAT technique holds great promise for future applications in biological science.

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Dynamic stiffening of the flagellar hook

Cited by 12 publications

References 56 publications

Stochastic fluctuations in the rotation of the bacterial flagellar motor

Stochastic fluctuations in the rotation of the bacterial flagellar motor

Spatio-temporal dynamics of the proton motive force on single bacterial cells

Three-dimensional single-particle tracking by interferometric scattering microscopy with a double-helix point spread function

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