Assembly and Dynamics of the Bacterial Flagellum

Armitage, Judith P.; Berry, Richard M.

doi:10.1146/annurev-micro-090816-093411

Cited by 63 publications

(50 citation statements)

References 108 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our work provides this information in quantitative detail. The biological function of stator remodeling is not fully understood, but both sensory and regulatory roles are possible (10). Load-dependent remodeling of stator units acts like regulated cylinder deactivation in car engines, increasing power output when the demand is high and decreasing output when the demand is low, which serves as a mechanism to save energy.…”

Section: R a F Tmentioning

confidence: 99%

“…The rotation of flagella (3, 4), powered by the bidirectional flagellar motor (5–7), drives motility in many bacteria. In Escherichia coli , the flagellar motor consists of over 20 different proteins that self-assemble at the cell wall in varying copy numbers (8–10). Motor structure (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Motor structure (Fig. 1A) includes a rotor embedded in the inner cell membrane, a drive shaft, and a flexible hook that transmits torque to the filament (10, 11). The C-ring, which contains copies of the proteins FliG, FliM, and FliN, is mounted on the cytoplasmic face of the rotor and is responsible for directional switching of the motor (12).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanosensitive remodeling of the bacterial flagellar motor is independent of direction of rotation

Wadhwa¹,

Berg³

2021

Preprint

View full text Add to dashboard Cite

Motility is critical for the survival and dispersal of bacteria, and it plays an important role during infection. How bacteria regulate motility is thus a question of broad interest. Regulation of bacterial motility by chemical stimuli is well studied, but recent work has added a new dimension to the problem of motility control. The bidirectional flagellar motor of the bacterium Escherichia coli recruits or releases torque-generating units (stator units) in response to changes in load. Here, we show that this mechanosensitive remodeling of the flagellar motor is independent of direction of rotation. Remodeling rate constants in clockwise rotating motors and in counterclockwise rotating motors, measured previously, fall on the same curve if plotted against torque. Increased torque decreases the off rate of stator units from the motor, thereby increasing the number of active stator units at steady state. A simple mathematical model based on observed dynamics provides quantitative insight into the underlying molecular interactions. The torque-dependent remodeling mechanism represents a robust strategy to quickly regulate output (torque) in response to changes in demand (load).SignificanceMacromolecular machines carry out most of the biological functions in living organisms. Despite their significance, we do not yet understand the rules that govern the self-assembly of large multi-protein complexes. The bacterial flagellar motor tunes the assembly of its torque-generating stator complex with changes in external load. Here, we report that clockwise and counterclockwise rotating motors have identical remodeling response to changes in the external load, suggesting a purely mechanical mechanism for this regulation. Autonomous control of self-assembly may be a general strategy for tuning the functional output of protein complexes. The flagellar motor is a prime example of a macromolecular machine in which the functional regulation of assembly can be rigorously studied.

show abstract

Section: R a F Tmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanosensitive remodeling of the bacterial flagellar motor is independent of direction of rotation

Wadhwa¹,

Berg³

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…They travel in fluids using flagella that extend from the cell surface. The flagella are assembled as a supramolecular structure composed of more than 20 types of component proteins (1–3). A rotary motor at the base of each flagellum serves as a power engine.…”

Section: Introductionmentioning

confidence: 99%

Role of the N- and C-terminal regions of FliF, the MS ring component inVibrioflagellar basal body

Kojima

Kajino

Hirano

et al. 2021

Preprint

View full text Add to dashboard Cite

The MS ring is a part of the flagellar basal body and formed by 34 subunits of FliF, which consists of a large periplasmic region and two transmembrane segments connected to the N- and C-terminal regions facing the cytoplasm. A cytoplasmic protein, FlhF, which determines the position and number of the basal body, supports MS ring formation in the membrane. In this study, we constructed FliF deletion mutants that lack 30 or 50 residues at the N-terminus (ΔN30 and ΔN50), and 83 (ΔC83) or 110 residues (ΔC110) at the C-terminus. The N-terminal deletions were functional and conferred motility of Vibrio cells, whereas the C-terminal deletions were nonfunctional. The mutants were expressed in Escherichia coli to determine whether an MS ring could still be assembled. When co-expressing ΔN30FliF or ΔN50FliF with FlhF, fewer MS rings were observed than with the expression of wild-type FliF, in the MS ring fraction, suggesting that the N-terminus interacts with FlhF. MS ring formation is probably inefficient without an additional factor or FlhF. The deletion of the C-terminal cytoplasmic region did not affect the ability of FliF to form an MS ring because a similar number of MS rings were observed for ΔC83FliF as with wild-type FliF, although further deletion of the second transmembrane segment (ΔC110FliF) abolished it. These results suggest that the terminal regions of FliF have distinct roles; the N-terminal region for efficient MS ring formation and the C-terminal region for MS ring function. The second transmembrane segment is indispensable for MS ring assembly.ImportanceThe bacterial flagellum is a supramolecular architecture involved in cell motility. At the base of the flagella, a rotary motor that begins to construct an MS ring in the cytoplasmic membrane comprises 34 transmembrane proteins (FliF). Here, we investigated the roles of the N and C terminal regions of FliF, which are MS rings. Unexpectedly, the cytoplasmic regions of FliF are not indispensable for the formation of the MS ring, but the N-terminus appears to assist in ring formation through recruitment of FlhF, which is essential for flagellar formation. The C-terminus is essential for motor formation or function.

show abstract

“…In many bacteria, the C-ring is composed of three types of proteins: FliG, FliM, and FliN. Mutations in these proteins result in defects with several phenotypes, such as flagellar formation, motor rotation, or switching between CCW and CW rotations (2, 3). The genotypes of the phenotypes are indicated by fla , mot , and che (4).…”

Section: Introductionmentioning

confidence: 99%

Function of theVibrioPomB plug region based on the stator rotation model for bacterial flagellar motor

Homma

Terashima

Koiwa

et al. 2021

Preprint

View full text Add to dashboard Cite

Bacterial flagella are the only real rotational motor organs in the biological world. The spiral-shaped flagellar filaments that extend from the cell surface rotate like a screw to create a propulsive force. The base of the flagellar filament has a protein motor consisting of a stator and a rotor embedded in the membrane. The motor part has stators composed of two types of membrane subunits, PomA(MotA) and PomB(MotB), which are energy converters coupled to the ion flow that assemble around the rotor. Recently, structures of the stator, in which two molecules of MotB stuck in the center of the MotA ring made of five molecules, were reported and a model in which the MotA ring rotates with respect to MotB, which is coupled to the influx of ions, was proposed. We focused on the Vibrio PomB plug region, which has been reported to control the activation of flagellar motors. We searched for the plug region, which is the interacting region, through site-directed photo-cross-linking and disulfide cross-linking experiments. Our results demonstrated that it interacts with the extracellular short loop region of PomA, which is between transmembrane 3 and 4. Although the motor halted following cross-linking, its function was recovered with a reducing reagent that disrupted the disulfide bond. Our results support the hypothesis, which has been inferred from the stator structure, that the plug region terminates the ion inflow by stopping the rotation of the rotor.

show abstract

Assembly and Dynamics of the Bacterial Flagellum

Cited by 63 publications

References 108 publications

Mechanosensitive remodeling of the bacterial flagellar motor is independent of direction of rotation

Mechanosensitive remodeling of the bacterial flagellar motor is independent of direction of rotation

Role of the N- and C-terminal regions of FliF, the MS ring component inVibrioflagellar basal body

Function of theVibrioPomB plug region based on the stator rotation model for bacterial flagellar motor

Contact Info

Product

Resources

About