scholarly journals Populational Heterogeneity vs. Temporal Fluctuation in Escherichia coli Flagellar Motor Switching

2013 ◽  
Vol 105 (9) ◽  
pp. 2123-2129 ◽  
Author(s):  
Fan Bai ◽  
Yong-Suk Che ◽  
Nobunori Kami-ike ◽  
Qi Ma ◽  
Tohru Minamino ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Flagellar Motor ◽  
Temporal Fluctuation

scholarly journals Clusters of Charged Residues at the C Terminus of MotA and N Terminus of MotB Are Important for Function of the Escherichia coli Flagellar Motor

2008 ◽  
Vol 190 (15) ◽  
pp. 5517-5521 ◽  
Author(s):  
Edan R. Hosking ◽  
Michael D. Manson
Keyword(s):  
Escherichia Coli ◽  
Flagellar Motor ◽  
Protein Levels ◽  
Partner Protein ◽  
C Terminus ◽  
N Terminus ◽  
Charged Residues ◽  
Positively Charged ◽  
Terminal Cluster

ABSTRACT MotA contains a conserved C-terminal cluster of negatively charged residues, and MotB contains a conserved N-terminal cluster of positively charged residues. Charge-altering mutations affecting these residues impair motility but do not diminish Mot protein levels. The motility defects are reversed by second-site mutations targeting the same or partner protein.

scholarly journals Site-Directed Cross-Linking Identifies the Stator-Rotor Interaction Surfaces in a Hybrid Bacterial Flagellar Motor

2021 ◽  
Vol 203 (9) ◽  
Author(s):  
Hiroyuki Terashima ◽  
Seiji Kojima ◽  
Michio Homma
Keyword(s):  
Escherichia Coli ◽  
Cross Linking ◽  
Physical Interaction ◽  
Flagellar Motor ◽  
Intact Cells ◽  
Content Type ◽  
Bacterial Flagellum ◽  
Cross Links ◽  
Bacterial Flagellar Motor ◽  
Rotary Motor

ABSTRACT The bacterial flagellum is the motility organelle powered by a rotary motor. The rotor and stator elements of the motor are located in the cytoplasmic membrane and cytoplasm. The stator units assemble around the rotor, and an ion flux (typically H+ or Na+) conducted through a channel of the stator induces conformational changes that generate rotor torque. Electrostatic interactions between the stator protein PomA in Vibrio (MotA in Escherichia coli) and the rotor protein FliG have been shown by genetic analyses but have not been demonstrated biochemically. Here, we used site-directed photo-cross-linking and disulfide cross-linking to provide direct evidence for the interaction. We introduced a UV-reactive amino acid, p-benzoyl-l-phenylalanine (pBPA), into the cytoplasmic region of PomA or the C-terminal region of FliG in intact cells. After UV irradiation, pBPA inserted at a number of positions in PomA and formed a cross-link with FliG. PomA residue K89 gave the highest yield of cross-links, suggesting that it is the PomA residue nearest to FliG. UV-induced cross-linking stopped motor rotation, and the isolated hook-basal body contained the cross-linked products. pBPA inserted to replace residue R281 or D288 in FliG formed cross-links with the Escherichia coli stator protein, MotA. A cysteine residue introduced in place of PomA K89 formed disulfide cross-links with cysteine inserted in place of FliG residues R281 and D288 and some other flanking positions. These results provide the first demonstration of direct physical interaction between specific residues in FliG and PomA/MotA. IMPORTANCE The bacterial flagellum is a unique organelle that functions as a rotary motor. The interaction between the stator and rotor is indispensable for stator assembly into the motor and the generation of motor torque. However, the interface of the stator-rotor interaction has only been defined by mutational analysis. Here, we detected the stator-rotor interaction using site-directed photo-cross-linking and disulfide cross-linking approaches. We identified several residues in the PomA stator, especially K89, that are in close proximity to the rotor. Moreover, we identified several pairs of stator and rotor residues that interact. This study directly demonstrates the nature of the stator-rotor interaction and suggests how stator units assemble around the rotor and generate torque in the bacterial flagellar motor.

scholarly journals Torque generated by the flagellar motor of Escherichia coli

1993 ◽  
Vol 65 (5) ◽  
pp. 2201-2216 ◽  
Author(s):  
H.C. Berg ◽  
L. Turner
Keyword(s):  
Escherichia Coli ◽  
Flagellar Motor

scholarly journals Structural insights into the mechanism of c-di-GMP–bound YcgR regulating flagellar motility in Escherichia coli

2019 ◽  
Vol 295 (3) ◽  
pp. 808-821 ◽  
Author(s):  
Yan-Jie Hou ◽  
Wen-Si Yang ◽  
Yuan Hong ◽  
Ying Zhang ◽  
Da-Cheng Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Motor Proteins ◽  
Flagellar Motor ◽  
Bacterial Survival ◽  
Flagellar Motility ◽  
Surface Attachment ◽  
Bacterial Surface ◽  
Motility Regulation ◽  
Survival And Growth ◽  
Structural Insights

The motile-sessile transition is critical for bacterial survival and growth. Cyclic-di-GMP (c-di-GMP) plays a central role in controlling this transition and regulating biofilm formation via various effectors. As an effector of c-di-GMP in Escherichia coli and related species, the PilZ domain–containing protein YcgR responds to elevated c-di-GMP concentrations and acts on the flagellar motor to suppress bacterial motility in a brakelike fashion, which promotes bacterial surface attachment. To date, several target proteins within the motor, MotA, FliG, and FliM, along with different regulatory mechanisms have been reported. However, how YcgR acts on these components remains unclear. Here, we report that activated YcgR stably binds to MotA at the MotA-FliG interface and thereby regulates bacterial swimming. Biochemical and structural analyses revealed that c-di-GMP rearranges the PilZ domain configuration, resulting in the formation of a MotA-binding patch consisting of an RXXXR motif and the C-tail helix α3. Moreover, we noted that a conserved region in the YcgR-N domain, which is independent of MotA interaction, is necessary for motility regulation. On the basis of these findings, we infer that the YcgR-N domain is required for activity on other motor proteins. We propose that activated YcgR appends to MotA via its PilZ domain and thereby interrupts the MotA-FliG interaction and simultaneously interacts with other motor proteins via its YcgR-N domain to inhibit flagellar motility. Our findings suggest that the mode of interaction between YcgR and motor proteins may be shared by other PilZ family proteins.

scholarly journals Biphasic chemotaxis ofEscherichia colito the microbiota metabolite indole

2020 ◽  
Vol 117 (11) ◽  
pp. 6114-6120 ◽  
Author(s):  
Jingyun Yang ◽  
Ravi Chawla ◽  
Kathy Y. Rhee ◽  
Rachit Gupta ◽  
Michael D. Manson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Microbial Communities ◽  
Bacterial Chemotaxis ◽  
Dynamic Responses ◽  
Time Dependent ◽  
Flagellar Motor ◽  
Wild Type ◽  
Gi Tract ◽  
Flagellar Motors

Bacterial chemotaxis to prominent microbiota metabolites such as indole is important in the formation of microbial communities in the gastrointestinal (GI) tract. However, the basis of chemotaxis to indole is poorly understood. Here, we exposedEscherichia colito a range of indole concentrations and measured the dynamic responses of individual flagellar motors to determine the chemotaxis response. Below 1 mM indole, a repellent-only response was observed. At 1 mM indole and higher, a time-dependent inversion from a repellent to an attractant response was observed. The repellent and attractant responses were mediated by the Tsr and Tar chemoreceptors, respectively. Also, the flagellar motor itself mediated a repellent response independent of the receptors. Chemotaxis assays revealed that receptor-mediated adaptation to indole caused a bipartite response—wild-type cells were attracted to regions of high indole concentration if they had previously adapted to indole but were otherwise repelled. We propose that indole spatially segregates cells based on their state of adaptation to repel invaders while recruiting beneficial resident bacteria to growing microbial communities within the GI tract.

scholarly journals Investigating Stator Dynamics of the Escherichia Coli Flagellar Motor

2013 ◽  
Vol 104 (2) ◽  
pp. 640a
Author(s):  
Laura E. Dickinson ◽  
Maarten M. van Oene ◽  
Francesco Pedaci ◽  
Bronwen Cross ◽  
Ren Lim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Flagellar Motor

scholarly journals Role of Motility and the flhDC Operon in Escherichia coli MG1655 Colonization of the Mouse Intestine

2007 ◽  
Vol 75 (7) ◽  
pp. 3315-3324 ◽  
Author(s):  
Eric J. Gauger ◽  
Mary P. Leatham ◽  
Regino Mercado-Lubo ◽  
David C. Laux ◽  
Tyrrell Conway ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Regulatory Region ◽  
Flagellar Motor ◽  
Wild Type ◽  
E Coli ◽  
Mouse Intestine ◽  
Flagellum Biosynthesis ◽  
Colonizing Ability

ABSTRACT Previously, we reported that the mouse intestine selected mutants of Escherichia coli MG1655 that have improved colonizing ability (M. P. Leatham et al., Infect. Immun. 73:8039-8049, 2005). These mutants grew 10 to 20% faster than their parent in mouse cecal mucus in vitro and 15 to 30% faster on several sugars found in the mouse intestine. The mutants were nonmotile and had deletions of various lengths beginning immediately downstream of an IS1 element located within the regulatory region of the flhDC operon, which encodes the master regulator of flagellum biosynthesis, FlhD4C2. Here we show that during intestinal colonization by wild-type E. coli strain MG1655, 45 to 50% of the cells became nonmotile by day 3 after feeding of the strain to mice and between 80 and 90% of the cells were nonmotile by day 15 after feeding. Ten nonmotile mutants isolated from mice were sequenced, and all were found to have flhDC deletions of various lengths. Despite this strong selection, 10 to 20% of the E. coli MG1655 cells remained motile over a 15-day period, suggesting that there is an as-yet-undefined intestinal niche in which motility is an advantage. The deletions appear to be selected in the intestine for two reasons. First, genes unrelated to motility that are normally either directly or indirectly repressed by FlhD4C2 but can contribute to maximum colonizing ability are released from repression. Second, energy normally used to synthesize flagella and turn the flagellar motor is redirected to growth.

scholarly journals Speed of the bacterial flagellar motor near zero load depends on the number of stator units

2017 ◽  
Vol 114 (44) ◽  
pp. 11603-11608 ◽  
Author(s):  
Ashley L. Nord ◽  
Yoshiyuki Sowa ◽  
Bradley C. Steel ◽  
Chien-Jung Lo ◽  
Richard M. Berry
Keyword(s):  
Escherichia Coli ◽  
Motive Force ◽  
Flagellar Motor ◽  
Single Curve ◽  
Ion Gradient ◽  
Membrane Bound ◽  
Bacterial Flagellar Motor ◽  
Ion Conducting ◽  
Relationship Of

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque–speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na+- and H+-driven motors. We measure the full torque–speed relationship of one and two H+units inEscherichia coliby selecting the number of H+units and controlling the number of Na+units in hybrid motors. These experiments confirm that speed near zero torque in H+-driven motors increases with the stator number. We also measured 75 torque–speed curves for Na+-driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque–speed curves to be collapsed onto a single curve by simple rescaling.

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