scholarly journals Genetic analysis of response regulator activation in bacterial chemotaxis suggests an intermolecular mechanism

2009 ◽  
Vol 11 (11) ◽  
pp. 2644-2654 ◽  
Author(s):  
Sandra Da Re ◽  
Tatiana Tolstykh ◽  
Peter M. Wolanin ◽  
Jeffry B. Stock
Keyword(s):  
Genetic Analysis ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Intermolecular Mechanism

scholarly journals Cellular Stoichiometry of Chemotaxis Proteins in Sinorhizobium meliloti

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Timofey D. Arapov ◽  
Rafael Castañeda Saldaña ◽  
Amanda L. Sebastian ◽  
W. Keith Ray ◽  
Richard F. Helm ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Sinorhizobium Meliloti ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Adaptor Proteins ◽  
Molar Ratio ◽  
Content Type ◽  
Chemotaxis Proteins ◽  
Chemotaxis System

ABSTRACT Chemotaxis systems enable microbes to sense their immediate environment, moving toward beneficial stimuli and away from those that are harmful. In an effort to better understand the chemotaxis system of Sinorhizobium meliloti, a symbiont of the legume alfalfa, the cellular stoichiometries of all ten chemotaxis proteins in S. meliloti were determined. A combination of quantitative immunoblot and mass spectrometry revealed that the protein stoichiometries in S. meliloti varied greatly from those in Escherichia coli and Bacillus subtilis. To compare protein ratios to other systems, values were normalized to the central kinase CheA. All S. meliloti chemotaxis proteins exhibited increased ratios to various degrees. The 10-fold higher molar ratio of adaptor proteins CheW1 and CheW2 to CheA might result in the formation of rings in the chemotaxis array that consist of only CheW instead of CheA and CheW in a 1:1 ratio. We hypothesize that the higher ratio of CheA to the main response regulator CheY2 is a consequence of the speed-variable motor in S. meliloti, instead of a switch-type motor. Similarly, proteins involved in signal termination are far more abundant in S. meliloti, which utilizes a phosphate sink mechanism based on CheA retrophosphorylation to inactivate the motor response regulator versus CheZ-catalyzed dephosphorylation as in E. coli and B. subtilis. Finally, the abundance of CheB and CheR, which regulate chemoreceptor methylation, was increased compared to CheA, indicative of variations in the adaptation system of S. meliloti. Collectively, these results mark significant differences in the composition of bacterial chemotaxis systems. IMPORTANCE The symbiotic soil bacterium Sinorhizobium meliloti contributes greatly to host-plant growth by fixing atmospheric nitrogen. The provision of nitrogen as ammonium by S. meliloti leads to increased biomass production of its legume host alfalfa and diminishes the use of environmentally harmful chemical fertilizers. To better understand the role of chemotaxis in host-microbe interaction, a comprehensive catalogue of the bacterial chemotaxis system is vital, including its composition, function, and regulation. The stoichiometry of chemotaxis proteins in S. meliloti has very few similarities to the systems in Escherichia coli and Bacillus subtilis. In addition, total amounts of proteins are significantly lower. S. meliloti exhibits a chemotaxis system distinct from known models by incorporating new proteins as exemplified by the phosphate sink mechanism.

scholarly journals Crystal Structure of the CheA Histidine Phosphotransfer Domain that Mediates Response Regulator Phosphorylation in Bacterial Chemotaxis

2001 ◽  
Vol 276 (33) ◽  
pp. 31074-31082 ◽  
Author(s):  
Lionel Mourey ◽  
Sandra Da Re ◽  
Jean-Denis Pédelacq ◽  
Tatiana Tolstykh ◽  
Cécile Faurie ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Histidine Phosphotransfer

scholarly journals CheX in the Three-Phosphatase System of Bacterial Chemotaxis

2007 ◽  
Vol 189 (19) ◽  
pp. 7007-7013 ◽  
Author(s):  
Travis J. Muff ◽  
Richard M. Foster ◽  
Peter J. Y. Liu ◽  
George W. Ordal
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Bacillus Subtilis ◽  
Mutant Strain ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Signal Transduction System ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Phosphatase System

ABSTRACT Bacterial chemotaxis involves the regulation of motility by a modified two-component signal transduction system. In Escherichia coli, CheZ is the phosphatase of the response regulator CheY but many other bacteria, including Bacillus subtilis, use members of the CheC-FliY-CheX family for this purpose. While Bacillus subtilis has only CheC and FliY, many systems also have CheX. The effect of this three-phosphatase system on chemotaxis has not been studied previously. CheX was shown to be a stronger CheY-P phosphatase than either CheC or FliY. In Bacillus subtilis, a cheC mutant strain was nearly complemented by heterologous cheX expression. CheX was shown to overcome the ΔcheC adaptational defect but also generally lowered the counterclockwise flagellar rotational bias. The effect on rotational bias suggests that CheX reduced the overall levels of CheY-P in the cell and did not truly replicate the adaptational effects of CheC. Thus, CheX is not functionally redundant to CheC and, as outlined in the discussion, may be more analogous to CheZ.

scholarly journals Swimming Escherichia coli explore the environment by Lévy walk

2021 ◽  
Author(s):  
Haiyan Huo ◽  
Rui He ◽  
Rongjing Zhang ◽  
Junhua Yuan
Keyword(s):  
Random Walk ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Random Fluctuation ◽  
Aqueous Environment ◽  
E Coli ◽  
Lévy Walk ◽  
Diffusion Characteristics ◽  
Levy Walk ◽  
Run Lengths

E. coli cells swim in aqueous environment in a random walk of alternating runs and tumbles. The diffusion characteristics of this random walk remains unclear. Here, by tracking the swimming of wildtype cells in a 3d homogeneous environment, we found that their trajectories are super diffusive, consistent with Lévy walk behavior. For comparison, we tracked the swimming of mutant cells that lack the chemotaxis signaling noise (the steady-state fluctuation of the concentration of the chemotaxis response regulator CheY-P), and found that their trajectories are normal diffusive. Therefore, wildtype E. coli cells explore the environment by Lévy walk, which originates from the chemotaxis signaling noise. This Lévy walk pattern enhances their efficiency in environmental exploration. Importance E. coli cells explore the environment in a random walk of alternating runs and tumbles. By tracking the 3d trajectories of E. coli cells in aqueous environment, we find that their trajectories are super diffusive, with a power-law shape for the distribution of run lengths, which is characteristics of Lévy walk. We further show that this Lévy walk behavior is due to the random fluctuation of the output level of the bacterial chemotaxis pathway, and it enhances the efficiency of the bacteria in exploring the environment.

scholarly journals Response thresholds in bacterial chemotaxis

2015 ◽  
Vol 1 (9) ◽  
pp. e1500299 ◽  
Author(s):  
Pushkar P. Lele ◽  
Abhishek Shrivastava ◽  
Thibault Roland ◽  
Howard C. Berg
Keyword(s):  
Escherichia Coli ◽  
Dynamic Range ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Wide Dynamic Range ◽  
Flagellar Motors ◽  
Response Thresholds ◽  
Stimulation Of

Stimulation ofEscherichia coliby exponential ramps of chemoattractants generates step changes in the concentration of the response regulator, CheY-P. Because flagellar motors are ultrasensitive, this should change the fraction of time that motors spin clockwise, the CWbias. However, early work failed to show changes in CWbiaswhen ramps were shallow. This was explained by a model for motor remodeling that predicted plateaus in plots of CWbiasversus [CheY-P]. We looked for these plateaus by examining distributions of CWbiasin populations of cells with different mean [CheY-P]. We did not find such plateaus. Hence, we repeated the work on shallow ramps and found that motors did indeed respond. These responses were quantitatively described by combining motor remodeling with ultrasensitivity in a model that exhibited high sensitivities over a wide dynamic range.

scholarly journals Diversity in Chemotaxis Mechanisms among the Bacteria and Archaea

2004 ◽  
Vol 68 (2) ◽  
pp. 301-319 ◽  
Author(s):  
Hendrik Szurmant ◽  
George W. Ordal
Keyword(s):  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Two Component System ◽  
E Coli ◽  
Cellular Processes ◽  
Intracellular Signal ◽  
The One ◽  
Chemotaxis System ◽  
Hydrolysis Of ◽  
Insight Into

SUMMARY The study of chemotaxis describes the cellular processes that control the movement of organisms toward favorable environments. In bacteria and archaea, motility is controlled by a two-component system involving a histidine kinase that senses the environment and a response regulator, a very common type of signal transduction in prokaryotes. Most insights into the processes involved have come from studies of Escherichia coli over the last three decades. However, in the last 10 years, with the sequencing of many prokaryotic genomes, it has become clear that E. coli represents a streamlined example of bacterial chemotaxis. While general features of excitation remain conserved among bacteria and archaea, specific features, such as adaptational processes and hydrolysis of the intracellular signal CheY-P, are quite diverse. The Bacillus subtilis chemotaxis system is considerably more complex and appears to be similar to the one that existed when the bacteria and archaea separated during evolution, so that understanding this mechanism should provide insight into the variety of mechanisms used today by the broad sweep of chemotactic bacteria and archaea. However, processes even beyond those used in E. coli and B. subtilis have been discovered in other organisms. This review emphasizes those used by B. subtilis and these other organisms but also gives an account of the mechanism in E. coli.

Sign in / Sign up

Export Citation Format

Share Document