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

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.

Download Full-text

Function of the Histone-Like Protein H-NS in Motility of Escherichia coli: Multiple Regulatory Roles Rather than Direct Action at the Flagellar Motor

Journal of Bacteriology ◽

10.1128/jb.00309-15 ◽

2015 ◽

Vol 197 (19) ◽

pp. 3110-3120 ◽

Cited By ~ 15

Author(s):

Eun A Kim ◽

David F. Blair

Keyword(s):

Escherichia Coli ◽

Direct Action ◽

Regulatory Protein ◽

Direct Interaction ◽

Flagellar Motor ◽

Flagellar Motility ◽

Standard View ◽

Content Type ◽

Regulatory Pathways ◽

Motor Interaction

ABSTRACTA number of investigations ofEscherichia colihave suggested that the DNA-binding protein H-NS, in addition to its well-known functions in chromosome organization and gene regulation, interacts directly with the flagellar motor to modulate its function. Here, in a study initially aimed at characterizing the H-NS/motor interaction further, we identify problems and limitations in the previous work that substantially weaken the case for a direct H-NS/motor interaction. Nullhnsmutants are immotile, largely owing to the downregulation of the flagellar master regulators FlhD and FlhC. We, and others, previously reported that anhnsmutant remains poorly motile even when FlhDC are expressed constitutively. In the present work, we use better-engineered strains to show that the motility defect in a Δhns, FlhDC-constitutive strain is milder than that reported previously and does not point to a direct action of H-NS at the motor. H-NS regulates numerous genes and might influence motility via a number of regulatory molecules besides FlhDC. To examine the sources of the motility defect that persists in an FlhDC-constitutive Δhnsmutant, we measured transcript levels and overexpression effects of a number of genes in candidate regulatory pathways. The results indicate that H-NS influences motility via multiple regulatory linkages that include, minimally, the messenger molecule cyclic di-GMP, the biofilm regulatory protein CsgD, and the sigma factors σSand σF. The results are in accordance with the more standard view of H-NS as a regulator of gene expression rather than a direct modulator of flagellar motor performance.IMPORTANCEData from a number of previous studies have been taken to indicate that the nucleoid-organizing protein H-NS influences motility not only by its well-known DNA-based mechanisms but also by binding directly to the flagellar motor to alter function. In this study, H-NS is shown to influence motility through diverse regulatory pathways, but a direct interaction with the motor is not supported. Previous indications of a direct action at the motor appear to be related to the use of nonnull strains and, in some cases, a failure to effectively bypass the requirement for H-NS in the expression of the flagellar regulon. These findings call for a substantially revised interpretation of the literature concerning H-NS and flagellar motility and highlight the importance of H-NS in diverse regulatory processes involved in the motile-sessile transition.

Download Full-text

Survival and Growth of Vibrio cholerae, Escherichia coli, and Salmonella Spp. in Well Water Used for Drinking Purposes in Garoua (North Cameroon)

International Journal of Bacteriology ◽

10.1155/2013/127179 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 9

Author(s):

Moussa Djaouda ◽

Bouba Gaké ◽

Daniel Ebang Menye ◽

Serge Hubert Zébazé Togouet ◽

Moïse Nola ◽

...

Keyword(s):

Escherichia Coli ◽

Vibrio Cholerae ◽

Well Water ◽

Bacterial Survival ◽

Bacterial Strains ◽

Salmonella Spp ◽

E Coli ◽

Antimicrobial Substances ◽

Survival And Growth ◽

Faecal Bacteria

The ability of strains of faecal bacteria (Vibrio cholerae, Escherichia coli ATCC 25922, and four strains of Salmonella isolated, resp., from well water, pig, poultry, and human urine in Garoua) to survive or grow in well water microcosms was compared. Water samples were obtained from two wells in Garoua (north Cameroun). Autoclaving at 121°C for 15 min and filtration through 0.2 µm filter were used to make microcosms. Microcosms were constituted of unfiltered-autoclaved, filtered-nonautoclaved, and filtered-autoclaved well waters. Bacterial strains were inoculated at initial cell concentration of 3 Log10CFU/mL. All strains were able to survive/grow in used microcosms, and a maximal concentration of 5.61 Log10CFU/mL was observed. Survival abilities were strain and microcosm dependent. The declines were more pronounced in filtered-nonautoclaved water than in the other microcosms. E. coli and Salmonella sp. (poultry strain) lowered to undetectable levels (<1 Log10CFU/mL) after two days of water storage. V. cholera decreased over time, but surviving cells persisted for longer period in filtered-nonautoclaved water from well W1 (1.91 Log10CFU/mL) and well W2 (2.09 Log10CFU/mL). Competition for nutrients and/or thermolabile antimicrobial substances synthesized by “ultramicrocells” or by the autochthonous bacteria retained by the filter might affect the bacterial survival.

Download Full-text

Potential for Internalization, Growth, and Survival of Salmonella and Escherichia coli O157:H7 in Oranges

Journal of Food Protection ◽

10.4315/0362-028x-67.8.1578 ◽

2004 ◽

Vol 67 (8) ◽

pp. 1578-1584 ◽

Cited By ~ 50

Author(s):

B. SHAWN EBLEN ◽

MARK O. WALDERHAUG ◽

SHARON EDELSON-MAMMEL ◽

STUART J. CHIRTEL ◽

ANTONIO DE JESUS ◽

...

Keyword(s):

Escherichia Coli ◽

Orange Juice ◽

Escherichia Coli O157 ◽

Bacterial Survival ◽

Human Pathogens ◽

Growth And Survival ◽

Survival And Growth ◽

Survival Studies ◽

Potential Conditions ◽

Dye Solutions

Internalization potential, survival, and growth of human pathogens within oranges were investigated in a series of laboratory experiments. Submerging oranges into dye solutions at various temperature differentials was used to assess internalization potential. Conditions in which dye internalization was observed were further studied by applying Escherichia coli O157: H7 or Salmonella onto the stem scar, subjecting the oranges to a temperature differential, juicing, and measuring numbers of pathogens in the resulting juice. Pathogens for growth and survival studies were applied to or injected into simulated peel punctures. Oranges with small peel holes of selected sizes were also placed into solutions containing these pathogens. Bacterial survival was also evaluated in orange juice at 4 and 24°C. Oranges internalized pathogens at a frequency of 2.5 to 3.0%, which mirrored dye internalization frequency (3.3%). Pathogens were internalized at an uptake level of 0.1 to 0.01% of the challenge applied. Bacteria grew within oranges at 24°C, but not at 4°C. Thirty-one percent of oranges with 0.91-mm surface holes showed pathogen uptake, whereas 2% of oranges with 0.68-mm holes showed pathogen uptake. Pathogens added to fresh orange juice and incubated at 24°C declined 1 log CFU/ml within 3 days. These results suggest that internalization, survival, and growth of human bacterial pathogens can occur within oranges intended for producing unpasteurized juice.

Download Full-text

Cyclic di-GMP differentially tunes a bacterial flagellar motor through a novel class of CheY-like regulators

eLife ◽

10.7554/elife.28842 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 35

Author(s):

Jutta Nesper ◽

Isabelle Hug ◽

Setsu Kato ◽

Chee-Seng Hee ◽

Judith Maria Habazettl ◽

...

Keyword(s):

Motor Activity ◽

Caulobacter Crescentus ◽

Chemical Information ◽

Flagellar Motor ◽

Cellular Functions ◽

Surface Attachment ◽

Chemical Proteomics ◽

Bacterial Surface ◽

Rotary Machine ◽

Motile Cells

The flagellar motor is a sophisticated rotary machine facilitating locomotion and signal transduction. Owing to its important role in bacterial behavior, its assembly and activity are tightly regulated. For example, chemotaxis relies on a sensory pathway coupling chemical information to rotational bias of the motor through phosphorylation of the motor switch protein CheY. Using a chemical proteomics approach, we identified a novel family of CheY-like (Cle) proteins in Caulobacter crescentus, which tune flagellar activity in response to binding of the second messenger c-di-GMP to a C-terminal extension. In their c-di-GMP bound conformation Cle proteins interact with the flagellar switch to control motor activity. We show that individual Cle proteins have adopted discrete cellular functions by interfering with chemotaxis and by promoting rapid surface attachment of motile cells. This study broadens the regulatory versatility of bacterial motors and unfolds mechanisms that tie motor activity to mechanical cues and bacterial surface adaptation.

Download Full-text

Metformin Alters the Chemotaxis and Flagellar Motility of Escherichia coli

Frontiers in Microbiology ◽

10.3389/fmicb.2021.792406 ◽

2022 ◽

Vol 12 ◽

Author(s):

Yingxiang Ye ◽

Panmei Jiang ◽

Chengyun Huang ◽

Jingyun Li ◽

Juan Chen ◽

...

Keyword(s):

Escherichia Coli ◽

Type 2 Diabetes ◽

Metabolic Syndrome ◽

Recovery Time ◽

Model Organism ◽

Flagellar Motor ◽

Flagellar Motility ◽

E Coli ◽

Intestinal Microorganism

Metformin is a biguanide molecule that is widely prescribed to treat type 2 diabetes and metabolic syndrome. Although it is known that metformin promotes the lifespan by altering intestinal microorganism metabolism, how metformin influences and alters the physiological behavior of microorganisms remains unclear. Here we studied the effect of metformin on the behavior alterations of the model organism Escherichia coli (E. coli), including changes in chemotaxis and flagellar motility that plays an important role in bacterial life. It was found that metformin was sensed as a repellent to E. coli by tsr chemoreceptors. Moreover, we investigated the chemotactic response of E. coli cultured with metformin to two typical attractants, glucose and α-methyl-DL-aspartate (MeAsp), finding that metformin prolonged the chemotactic recovery time to the attractants, followed by the recovery time increasing with the concentration of stimulus. Metformin also inhibited the flagellar motility of E. coli including the flagellar motor rotation and cell swimming. The inhibition was due to the reduction of torque generated by the flagellar motor. Our discovery that metformin alters the behavior of chemotaxis and flagellar motility of E. coli could provide potential implications for the effect of metformin on other microorganisms.

Download Full-text

Fate of Escherichia coli O157:H7 and Listeria monocytogenes in Strawberry Juice and Acidified Media at Different pH Values and Temperatures†

Journal of Food Protection ◽

10.4315/0362-028x-67.11.2443 ◽

2004 ◽

Vol 67 (11) ◽

pp. 2443-2449 ◽

Cited By ~ 34

Author(s):

Y. HAN ◽

R. H. LINTON

Keyword(s):

Escherichia Coli ◽

Listeria Monocytogenes ◽

Ph Value ◽

Escherichia Coli O157 ◽

Bacterial Survival ◽

E Coli ◽

Ph Values ◽

The Media ◽

Survival And Growth ◽

Strawberry Juice

Survival and growth of Escherichia coli O157:H7 and Listeria monocytogenes in strawberry juice and acidified media at different pH levels (pH 3.4 to 6.8) and temperatures were studied. Sterile strawberry juice (pH 3.6) and acidified trypticase soy broth (TSB) media (pH 3.4 to 6.8) were inoculated with approximately 6.7 log CFU/ml E. coli O157:H7 or 7.3 log CFU/ml L. monocytogenes, incubated for 3 days at 4 and 37°C. Bacterial levels were determined after 2 h, 1 day, and 3 days using surface plating nonselectively on tryptic soy agar and selectively on sorbitol MacConkey agar for E. coli O157:H7 or modified Oxford agar for L. monocytogenes. A spectrophotometer (660 nm) was also used to study growth inhibition of L. monocytogenes in different TSB and strawberry juice media (pH 3.4 to 7.3). E. coli O157:H7 survived well at pH values of 3.4 to 6.8 at 4°C, but the number of injured cells increased as pH decreased and incubation time increased. At 37°C, E. coli O157:H7 was inactivated at pH of ≤3.6 but could grow at pH 4.7. L. monocytogenes was quickly injured at pH of ≤4.7 within 2 h of storage at 4°C and then was slightly and gradually inactivated as storage time increased. L. monocytogenes survived well at pH 6.8 at 4°C and grew well at 37°C. Growth of L. monocytogenes at 37°C was inhibited in TSB by 1% citric acid and 0.5% malic acids at pH 3.4 or by 50% strawberry juice at pH 4.7. Bacterial injury and inactivation appeared to be induced by the acids in strawberry juice. The acids, pH value, temperature, and time were important factors for bacterial survival, inactivation, and growth in the media tested.

Download Full-text