scholarly journals Spontaneous adaptation of ion selectivity in a bacterial flagellar motor

2021 ◽  
Author(s):  
Pietro Ridone ◽  
Tsubasa Ishida ◽  
Yoshiyuki Sowa ◽  
Matthew A. B. Baker
Keyword(s):  
Genome Engineering ◽  
Environmental Changes ◽  
Ion Selectivity ◽  
Bacterial Species ◽  
Selective Advantage ◽  
Flagellar Motor ◽  
Novel Mutations ◽  
Power Sources ◽  
Motor Complex ◽  
Bacterial Flagellar Motor

ABSTRACTMotility provides a selective advantage to many bacterial species and is often achieved by rotation of flagella that propel the cell towards more favourable conditions. In most species, the rotation of the flagellum, driven by the Bacterial Flagellar Motor (BFM), is powered by H+ or Na+ ion transit through the torque-generating stator subunits of the motor complex. The ionic requirements for motility appear to have adapted to environmental changes throughout history but the molecular basis of this adaptation, and the constraints which govern the evolution of the stator proteins are unknown. Here we use CRISPR-mediated genome engineering to replace the native H+-powered stator genes of Escherichia coli with a compatible sodium-powered stator set from Vibrio alginolyticus and subsequently direct the evolution of the stators to revert to H+-powered motility. Evidence from whole genome sequencing indicates both flagellar- and non-flagellar-associated genes that are involved in longer-term adaptation to new power sources. Overall, transplanted Na+-powered stator genes can spontaneously incorporate novel mutations that allow H+-motility when environmental Na+ is lacking.

scholarly journals Loss of the Bacterial Flagellar Motor Switch Complex upon Cell Lysis

mBio ◽  
2021 ◽  
Author(s):  
Mohammed Kaplan ◽  
Elitza I. Tocheva ◽  
Ariane Briegel ◽  
Megan J. Dobro ◽  
Yi-Wei Chang ◽  
...  
Keyword(s):  
Self Assembly ◽  
Bacterial Species ◽  
Cell Lysis ◽  
Flagellar Motor ◽  
Bacterial Flagellar Motor

The bacterial flagellar motor is a complex macromolecular machine whose function and self-assembly present a fascinating puzzle for structural biologists. Here, we report that in diverse bacterial species, cell lysis leads to loss of the cytoplasmic switch complex and associated ATPase before other components of the motor.

scholarly journals Mutations in The Stator Protein PomA Affect Switching of Rotational Direction in Bacterial Flagellar Motor

2021 ◽  
Author(s):  
Hiroyuki Terashima ◽  
Kiyoshiro Hori ◽  
Kunio Ihara ◽  
Michio Homma ◽  
Seiji Kojima
Keyword(s):  
Motor Function ◽  
Flagellar Motor ◽  
Structural Studies ◽  
Novel Mutations ◽  
Interaction Site ◽  
Rotational Force ◽  
Bacterial Flagellar Motor ◽  
B Subunits ◽  
Rotational Direction ◽  
Rotational Power

Abstract The flagellar motor rotates bi-directionally in counter-clockwise (CCW) and clockwise (CW) directions. The motor consists of a stator and a rotor. Recent structural studies have revealed that the stator is composed of a pentameric ring of A subunits and a dimer axis of B subunits. The stator interacts with the rotor through conserved charged and neighboring residues, and the rotational power is generated by their interactions through a gear-like mechanism. The rotational direction is controlled by chemotaxis signaling transmitted to the rotor, with no evidence for the stator being involved. In this study, we found novel mutations that affect the switching of the rotational direction at the putative interaction site of the stator to generate rotational force. Our results highlight a novel aspect of flagellar motor function that appropriate switching of the interaction states between the stator and rotor is critical for controlling the rotational direction.

scholarly journals Construction and Loss of Bacterial Flagellar Filaments

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1528
Author(s):  
Xiang-Yu Zhuang ◽  
Chien-Jung Lo
Keyword(s):  
Bacterial Species ◽  
Flagellar Motor ◽  
Growth Data ◽  
Membrane Component ◽  
Long Distance ◽  
New Findings ◽  
Flagellar Filament ◽  
Experimental Works ◽  
Bacterial Flagellar Motor ◽  
Macro Molecule

The bacterial flagellar filament is an extracellular tubular protein structure that acts as a propeller for bacterial swimming motility. It is connected to the membrane-anchored rotary bacterial flagellar motor through a short hook. The bacterial flagellar filament consists of approximately 20,000 flagellins and can be several micrometers long. In this article, we reviewed the experimental works and models of flagellar filament construction and the recent findings of flagellar filament ejection during the cell cycle. The length-dependent decay of flagellar filament growth data supports the injection-diffusion model. The decay of flagellar growth rate is due to reduced transportation of long-distance diffusion and jamming. However, the filament is not a permeant structure. Several bacterial species actively abandon their flagella under starvation. Flagellum is disassembled when the rod is broken, resulting in an ejection of the filament with a partial rod and hook. The inner membrane component is then diffused on the membrane before further breakdown. These new findings open a new field of bacterial macro-molecule assembly, disassembly, and signal transduction.

scholarly journals Structural differences in the bacterial flagellar motor among bacterial species

2017 ◽  
Vol 14 (0) ◽  
pp. 191-198 ◽  
Author(s):  
Hiroyuki Terashima ◽  
Akihiro Kawamoto ◽  
Yusuke V. Morimoto ◽  
Katsumi Imada ◽  
Tohru Minamino
Keyword(s):  
Bacterial Species ◽  
Flagellar Motor ◽  
Structural Differences ◽  
Bacterial Flagellar Motor

scholarly journals Load-dependent adaptation near zero load in the bacterial flagellar motor

2019 ◽  
Vol 16 (159) ◽  
pp. 20190300 ◽  
Author(s):  
Jasmine A. Nirody ◽  
Ashley L. Nord ◽  
Richard M. Berry
Keyword(s):  
Large Range ◽  
Rotation Speed ◽  
Transmembrane Protein ◽  
Bacterial Species ◽  
Rotating Magnetic Field ◽  
Flagellar Motor ◽  
Superparamagnetic Beads ◽  
Bacterial Flagellar Motor ◽  
External Loads ◽  
Bond Mechanism

The bacterial flagellar motor is an ion-powered transmembrane protein complex which drives swimming in many bacterial species. The motor consists of a cytoplasmic ‘rotor’ ring and a number of ‘stator’ units, which are bound to the cell wall of the bacterium. Recently, it has been shown that the number of functional torque-generating stator units in the motor depends on the external load, and suggested that mechanosensing in the flagellar motor is driven via a ‘catch bond’ mechanism in the motor’s stator units. We present a method that allows us to measure—on a single motor—stator unit dynamics across a large range of external loads, including near the zero-torque limit. By attaching superparamagnetic beads to the flagellar hook, we can control the motor’s speed via a rotating magnetic field. We manipulate the motor to four different speed levels in two different ion-motive force (IMF) conditions. This framework allows for a deeper exploration into the mechanism behind load-dependent remodelling by separating out motor properties, such as rotation speed and energy availability in the form of IMF, that affect the motor torque.

scholarly journals Relaxation time asymmetry in stator dynamics of the bacterial flagellar motor

2021 ◽  
Author(s):  
Ruben Perez-Carrasco ◽  
María-José Franco-Oñate ◽  
Jean-Charles Walter ◽  
Jérôme Dorignac ◽  
Fred Geniet ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Molecular Motor ◽  
Bacterial Species ◽  
Potential Effect ◽  
Flagellar Motor ◽  
Time Asymmetry ◽  
Subunit Exchange ◽  
Multimeric Complex ◽  
Bacterial Flagellar Motor ◽  
Dynamic Exchange

The bacterial flagellar motor (BFM) is the membrane-embedded rotary molecular motor which turns the flagellum that provides thrust to many bacterial species. This large multimeric complex, composed of a few dozen constituent proteins, has emerged as a hallmark of dynamic subunit exchange. The stator units are inner-membrane ion channels which dynamically bind and unbind to the peptidoglycan at the rotor periphery, consuming the ion motive force (IMF) and applying torque to the rotor when bound. The dynamic exchange is known to be a function of the viscous load on the flagellum, allowing the bacterium to dynamically adapt to its local viscous environment, but the molecular mechanisms of exchange and mechanosensitivity remain to be revealed. Here, by actively perturbing the steady-state stator stoichiometry of individual motors, we reveal a stoichiometry-dependent asymmetry in stator remodeling kinetics. We interrogate the potential effect of next-neighbor interactions and local stator unit depletion and find that neither can explain the observed asymmetry. We then simulate and fit two mechanistically diverse models which recapitulate the asymmetry, finding stator assembly dynamics to be particularly well described by a two-state catch-bond mechanism.

scholarly journals Cooperative stator assembly of bacterial flagellar motor mediated by rotation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kenta I. Ito ◽  
Shuichi Nakamura ◽  
Shoichi Toyabe
Keyword(s):  
Environmental Changes ◽  
Dynamic Structure ◽  
Central Place ◽  
Flagellar Motor ◽  
Biological Regulation ◽  
Highly Sensitive ◽  
Dynamic Assembly ◽  
Type Coupling ◽  
Bacterial Flagellar Motor ◽  
Torque Regulation

AbstractCooperativity has a central place in biological regulation, providing robust and highly-sensitive regulation. The bacterial flagellar motor implements autonomous torque regulation based on the stator’s dynamic structure; the stator units bind to and dissociate from the motor dynamically in response to environmental changes. However, the mechanism of this dynamic assembly is not fully understood. Here, we demonstrate the cooperativity in the stator assembly dynamics. The binding is slow at the stalled state, but externally forced rotation as well as driving by motor torque in either direction boosts the stator binding. Hence, once a stator unit binds, it drives the rotor and triggers the avalanche of succeeding bindings. This cooperative mechanism based on nonequilibrium allostery accords with the recently-proposed gear-type coupling between the rotor and stator.

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