Asymmetric random walks reveal that the chemotaxis network modulates flagellar rotational bias in Helicobacter pylori

Abstract

The canonical chemotaxis network modulates the bias for a particular direction of rotation in the bacterial flagellar motor to help the cell migrate toward favorable chemical environments. How the chemotaxis network in Helicobacter pylori modulates flagellar functions is unknown, which limits our understanding of chemotaxis in this species. Here, we determined that H. pylori swim faster (slower) whenever their flagella rotate counterclockwise (clockwise) by analyzing their hydrodynamic interactions with bounding surfaces. This asymmetry in swimming helped quantify the rotational bias. Upon exposure to a chemo-attractant, the bias decreased and the cells tended to swim exclusively in the faster mode. In the absence of a key chemotaxis protein, CheY, the bias was zero. The relationship between the reversal frequency and the rotational bias was unimodal. Thus, H. pylori’s chemotaxis network appears to modulate the probability of clockwise rotation in otherwise counterclockwise-rotating flagella, similar to the canonical network.

Transitioning to confined spaces impacts bacterial swimming and escape response

“…Interestingly, a prior report has also described a difference in trajectory curvature between forward and reverse swimming, especially near a single surface (38). As we did not observe a noticeable difference in translational or angular speed by confined V. fischeri before or after reversals, two-sided confinement may balance out differences between reversal-associated swimming modes, potentially influencing reversals, escape behavior, and other directional movement (39)(40)(41)(42).…”

Transitioning to confined spaces impacts bacterial swimming and escape response

“…Interestingly, a prior report has also described a difference in trajectory curvature between forward and reverse swimming, especially near a single surface (37). As we did not observe a noticeable difference in translational or angular speed by confined V. fischeri before or after reversals, two-sided confinement may balance out differences between reversal-associated swimming modes, potentially influencing reversals, escape behavior, and other directional movement (38)(39)(40)(41).…”

Clostridioides difficile Single Cell Swimming Strategy: A Novel Motility Pattern Regulated by Viscoelastic Properties of the Environment

“…Generally, flagella have an energetically favourable turning direction ( Antani et al, 2021 ). In some species a difference in torque profile based on rotational direction, likely due to stator-rotor interactions, could be shown, which leads to different motility parameter for clockwise/counter-clockwise rotation ( Yuan et al, 2010 ; Minamino et al, 2019 ).…”