Robustness in an Ultrasensitive Motor

Liu, Guangzhe; Tao, Antai; Zhang, Rongjing; Yuan, Junhua

doi:10.1128/mbio.03050-19

Cited by 7 publications

(7 citation statements)

References 35 publications

(40 reference statements)

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“…A fraction of the data is shown in Figure 3B and in Appendix 1—figure 1 . This suggested that the default direction of flagellar rotation is CCW, similar to E. coli ( Ford et al, 2018 ; Liu et al, 2020 ). Considering that the bias is zero in the absence and ~0.35 in the presence of CheY, CheY-P binding likely promotes CW rotation in an otherwise CCW rotating motor in H. pylori .…”

Section: Resultsmentioning

confidence: 96%

Asymmetric random walks reveal that the chemotaxis network modulates flagellar rotational bias in Helicobacter pylori

Antani

Sumali

Lele

et al. 2021

eLife

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The canonical chemotaxis network modulates the bias for a particular direction of rotation in the bacterial flagellar motor to help the cell migrate toward favorable chemical environments. How the chemotaxis network in Helicobacter pylori modulates flagellar functions is unknown, which limits our understanding of chemotaxis in this species. Here, we determined that H. pylori swim faster (slower) whenever their flagella rotate counterclockwise (clockwise) by analyzing their hydrodynamic interactions with bounding surfaces. This asymmetry in swimming helped quantify the rotational bias. Upon exposure to a chemo-attractant, the bias decreased and the cells tended to swim exclusively in the faster mode. In the absence of a key chemotaxis protein, CheY, the bias was zero. The relationship between the reversal frequency and the rotational bias was unimodal. Thus, H. pylori’s chemotaxis network appears to modulate the probability of clockwise rotation in otherwise counterclockwise-rotating flagella, similar to the canonical network.

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Section: Resultsmentioning

confidence: 96%

Asymmetric random walks reveal that the chemotaxis network modulates flagellar rotational bias in Helicobacter pylori

Antani

Sumali

Lele

et al. 2021

eLife

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“…After removal of metformin, the motor CW bias decreased to the pre-stimulus level rapidly. The chemotaxis system of E. coli is a robust adaptive system which allows the bacteria to sense and respond rapidly to the changes in the environment ( Alon et al, 1999 ; Liu G. et al, 2020 ). The motor CW bias was recovered to the initial level after rapid adaptation to the external attractant or repellent.…”

Section: Resultsmentioning

confidence: 99%

“…The results indicate that metformin prolonged the chemotactic recovery time of E. coli to the attractant. Previous findings revealed that the chemotaxis adaptation of E. coli to the attractant was ultrasensitive, wide-ranged, and robust ( Alon et al, 1999 ; Mello and Tu, 2007 ; Liu G. et al, 2020 ). In this study, we showed that the chemotactic response of wild-type cells for chemotaxis cultured in metformin to the attractant was different from cells cultured without metformin, in spite of the overall tendency of chemotactic response being similar.…”

Section: Discussionmentioning

confidence: 99%

Metformin Alters the Chemotaxis and Flagellar Motility of Escherichia coli

Jiang

Huang

et al. 2022

Front. Microbiol.

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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.

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“…The bacterial flagellar motor is ultrasensitive to the free CheY-P in the cytoplasm [ 49 , 50 , 51 ]. Without question, any slight change of the binding affinity of CheY for FliM will significantly affect the function of CheY in controlling flagellar motor.…”

Section: Discussionmentioning

confidence: 99%

The Divergent Key Residues of Two Agrobacterium fabrum (tumefaciens) CheY Paralogs Play a Key Role in Distinguishing Their Functions

et al. 2021

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The chemotactic response regulator CheY, when phosphorylated by the phosphoryl group from phosphorylated CheA, can bind to the motor switch complex to control the flagellar motor rotation. Agrobacterium fabrum (previous name: Agrobacterium tumefaciens), a phytopathogen, carries two paralogous cheY genes, cheY1 and cheY2. The functional difference of two paralogous CheYs remains unclear. Three cheY-deletion mutants were constructed to test the effects of two CheYs on the chemotaxis of A. fabrum. Phenotypes of three cheY-deletion mutants show that deletion of each cheY significantly affects the chemotactic response, but cheY2-deletion possesses more prominent effects on the chemotactic migration and swimming pattern of A. fabrum than does cheY1-deletion. CheA-dependent cellular localization of two CheY paralogs and in vitro pull-down of two CheY paralogs by FliM demonstrate that the distinct roles of two CheY paralogs arise mainly from the differentiation of their binding affinities for the motor switch component FliM, agreeing with the divergence of the key residues on the motor-binding surface involved in the interaction with FliM. The single respective replacements of key residues R93 and A109 on the motor-binding surface of CheY2 by alanine (A) and valine (V), the corresponding residues of CheY1, significantly enhanced the function of CheY2 in regulating the chemotactic response of A. fabrum CheY-deficient mutant Δy to nutrient substances and host attractants. These results conclude that the divergence of the key residues in the functional subdomain is the decisive factor of functional differentiation of these two CheY homologs and protein function may be improved by the substitution of the divergent key residues in the functional domain for the corresponding residues of its paralogs. This finding will help us to better understand how paralogous proteins sub-functionalize. In addition, the acquirement of two CheY2 variants, whose chemotactic response functions are significantly improved, will be very useful for us to further explore the mechanism of CheY to bind and regulate the flagellar motor and the role of chemotaxis in the pathogenicity of A. fabrum.

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Robustness in an Ultrasensitive Motor

Cited by 7 publications

References 35 publications

Asymmetric random walks reveal that the chemotaxis network modulates flagellar rotational bias in Helicobacter pylori

Asymmetric random walks reveal that the chemotaxis network modulates flagellar rotational bias in Helicobacter pylori

Metformin Alters the Chemotaxis and Flagellar Motility of Escherichia coli

The Divergent Key Residues of Two Agrobacterium fabrum (tumefaciens) CheY Paralogs Play a Key Role in Distinguishing Their Functions

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