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 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 Flagella-Driven Motility of Bacteria

Biomolecules ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 279 ◽  
Author(s):  
Shuichi Nakamura ◽  
Tohru Minamino
Keyword(s):  
Cell Body ◽  
Molecular Mechanisms ◽  
Bacterial Species ◽  
Structural Diversity ◽  
Flagellar Motor ◽  
Bacterial Flagellum ◽  
Structure And Dynamics ◽  
Ring Complex ◽  
Flagellar Filament ◽  
Experimental And Theoretical Studies

The bacterial flagellum is a helical filamentous organelle responsible for motility. In bacterial species possessing flagella at the cell exterior, the long helical flagellar filament acts as a molecular screw to generate thrust. Meanwhile, the flagella of spirochetes reside within the periplasmic space and not only act as a cytoskeleton to determine the helicity of the cell body, but also rotate or undulate the helical cell body for propulsion. Despite structural diversity of the flagella among bacterial species, flagellated bacteria share a common rotary nanomachine, namely the flagellar motor, which is located at the base of the filament. The flagellar motor is composed of a rotor ring complex and multiple transmembrane stator units and converts the ion flux through an ion channel of each stator unit into the mechanical work required for motor rotation. Intracellular chemotactic signaling pathways regulate the direction of flagella-driven motility in response to changes in the environments, allowing bacteria to migrate towards more desirable environments for their survival. Recent experimental and theoretical studies have been deepening our understanding of the molecular mechanisms of the flagellar motor. In this review article, we describe the current understanding of the structure and dynamics of the bacterial flagellum.

scholarly journals The Architectural Dynamics of the Bacterial Flagellar Motor Switch

Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 833
Author(s):  
Shahid Khan
Keyword(s):  
Single Molecule ◽  
Protein Interactions ◽  
Cell Biophysics ◽  
Flagellar Motor ◽  
Research Strategies ◽  
The Core ◽  
Switch Operation ◽  
Flagellar Filament ◽  
Bacterial Flagellar Motor ◽  
New Research

The rotary bacterial flagellar motor is remarkable in biochemistry for its highly synchronized operation and amplification during switching of rotation sense. The motor is part of the flagellar basal body, a complex multi-protein assembly. Sensory and energy transduction depends on a core of six proteins that are adapted in different species to adjust torque and produce diverse switches. Motor response to chemotactic and environmental stimuli is driven by interactions of the core with small signal proteins. The initial protein interactions are propagated across a multi-subunit cytoplasmic ring to switch torque. Torque reversal triggers structural transitions in the flagellar filament to change motile behavior. Subtle variations in the core components invert or block switch operation. The mechanics of the flagellar switch have been studied with multiple approaches, from protein dynamics to single molecule and cell biophysics. The architecture, driven by recent advances in electron cryo-microscopy, is available for several species. Computational methods have correlated structure with genetic and biochemical databases. The design principles underlying the basis of switch ultra-sensitivity and its dependence on motor torque remain elusive, but tantalizing clues have emerged. This review aims to consolidate recent knowledge into a unified platform that can inspire new research strategies.

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 Shoot–root carbon allocation, sugar signalling and their coupling with nitrogen uptake and assimilation

2016 ◽  
Vol 43 (2) ◽  
pp. 105 ◽  
Author(s):  
Lu Wang ◽  
Yong-Ling Ruan
Keyword(s):  
Growth And Development ◽  
Carbon Allocation ◽  
Dynamic Balance ◽  
Shoot Development ◽  
Long Distance ◽  
Root Carbon ◽  
Organ Systems ◽  
New Findings ◽  
Sugar Signalling

Roots and shoots are distantly located but functionally interdependent. The growth and development of these two organ systems compete for energy and nutrient resource, and yet, they keep a dynamic balance with each other for growth and development. The success of such a relationship depends on efficient root-shoot communication. Aside from the well-known signalling processes mediated by hormones such as auxin and cytokinin, sugars have recently been shown to act as a rapid signal to co-ordinate root and shoot development in response to endogenous and exogenous clues, in parallel to their function as carbon and energy resources for biomass production. New findings from studies on vascular fluids have provided molecular insights into the role of sugars in long-distance communications between shoot and root. In this review, we discussed phloem- and xylem- translocation of sugars and the impacts of sugar allocation and signalling on balancing root–shoot development. Also, we have taken the shoot–root carbon–nitrogen allocation as an example to illustrate the communication between the two organs through multi-layer root–shoot–root signalling circuits, comprising sugar, nitrogen, cytokinin, auxin and vascular small peptide signals.

scholarly journals Bacterial Flagellar Filament: A Supramolecular Multifunctional Nanostructure

2021 ◽  
Vol 22 (14) ◽  
pp. 7521
Author(s):  
Marko Nedeljković ◽  
Diego Emiliano Sastre ◽  
Eric John Sundberg
Keyword(s):  
Immune Responses ◽  
Basal Body ◽  
Vaccine Development ◽  
Bacterial Species ◽  
High Variability ◽  
Bacterial Survival ◽  
Bacterial Flagellum ◽  
Capping Proteins ◽  
Flagellar Filament ◽  
Flagellar Assembly

The bacterial flagellum is a complex and dynamic nanomachine that propels bacteria through liquids. It consists of a basal body, a hook, and a long filament. The flagellar filament is composed of thousands of copies of the protein flagellin (FliC) arranged helically and ending with a filament cap composed of an oligomer of the protein FliD. The overall structure of the filament core is preserved across bacterial species, while the outer domains exhibit high variability, and in some cases are even completely absent. Flagellar assembly is a complex and energetically costly process triggered by environmental stimuli and, accordingly, highly regulated on transcriptional, translational and post-translational levels. Apart from its role in locomotion, the filament is critically important in several other aspects of bacterial survival, reproduction and pathogenicity, such as adhesion to surfaces, secretion of virulence factors and formation of biofilms. Additionally, due to its ability to provoke potent immune responses, flagellins have a role as adjuvants in vaccine development. In this review, we summarize the latest knowledge on the structure of flagellins, capping proteins and filaments, as well as their regulation and role during the colonization and infection of the host.

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