Communication Dans Un Congrès Année : 2023

Signature of (anti)cooperativity in the stochastic fluctuations of small systems: application to the bacterial flagellar motor

Francesco Pedaci
Ashley Nord

Résumé

The cooperative binding of molecular agents onto a substrate is pervasive in living systems. To study whether a system shows cooperativity, one can rely on a fluctuation analysis of quantities such as the number of substrate-bound units and the residence time in an occupancy state. Since the relative standard deviation from the statistical mean monotonically decreases with the number of binding sites, these techniques are only suitable for small enough systems, such as those implicated in stochastic processes inside cells. Here, we present a general-purpose grand canonical Hamiltonian description of a small one-dimensional (1D) lattice gas with either nearest-neighbor or long-range interactions as prototypical examples of cooperativity-influenced adsorption processes. First, we elucidate how the strength and sign of the interaction potential between neighboring bound particles on the lattice determine the intensity of the fluctuations of the mean occupancy. We then employ this relationship to compare the theoretical predictions of our model to data from single molecule experiments on bacterial flagellar motors (BFM) of E. coli. In this way, we find evidence that cooperativity controls the mechano-sensitive dynamical assembly of the torque-generating units, the so-called stator units, onto the BFM. Furthermore, in an attempt to quantify fluctuations and the adaptability of the BFM, we estimate the stator-stator interaction potential. Finally, we conclude that the system resides in a sweet spot of the parameter space (phase diagram) with characteristics suitable for a smoothly and widely adaptive system, while minimizing fluctuations. https://arxiv.org/abs/2307.00636v2
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Dates et versions

hal-04890444 , version 1 (16-01-2025)

Identifiants

  • HAL Id : hal-04890444 , version 1

Citer

John Palmeri, Maria-José Franco-Oñate, Nils-Ole Walliser, Andrea Parmeggiani, Jerome Dorignac, et al.. Signature of (anti)cooperativity in the stochastic fluctuations of small systems: application to the bacterial flagellar motor. International Physics of Living Systems (IPOLS) 2023, Daniel Goldman, Georgia Tech, Aug 2023, Atlanta (Georgia), United States. ⟨hal-04890444⟩
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