Structural similarities between the aspartate receptor of bacterial chemotaxis and the trp repressor of E. coli Implications for transmembrane signaling

FEBS Letters ◽  
1992 ◽  
Vol 307 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Berkley A. Lynch ◽  
Daniel E. Koshland
Keyword(s):  
Bacterial Chemotaxis ◽  
Transmembrane Signaling ◽  
Trp Repressor ◽  
E Coli ◽  
Aspartate Receptor

Evolutionary divergence of the Citrobacter freundii tryptophan operon regulatory region: comparison with other enteric bacteria

1982 ◽  
Vol 152 (1) ◽  
pp. 57-62
Author(s):  
M Blumenberg ◽  
C Yanofsky
Keyword(s):  
Regulatory Region ◽  
Enteric Bacteria ◽  
Evolutionary Divergence ◽  
Citrobacter Freundii ◽  
Initial Portion ◽  
Trp Repressor ◽  
E Coli ◽  
Weak Expression ◽  
Dyad Symmetry ◽  
Trp Operon

The regulatory region of the trp operon of Citrobacter freundii was sequenced and compared with the corresponding regions of other enteric bacteria. Significant differences were noted in the promoter region. These differences are presumably responsible for the weak expression of the cloned trp operon in Escherichia coli. The presumed operator region, although nonfunctional in E. coli, has dyad symmetry, but the sequence of the symmetrical region differs appreciably from those of operators that can be regulated by the E. coli trp repressor. The sequence of the trp leader region of C. freundii resembles that of other enteric bacteria, suggesting that the C. freundii operon is also regulated by attenuation. Comparison of the sequence of the initial portion of trpE with the homologous regions of E. coli and Salmonella typhimurium indicates that the three organisms probably are evolutionary equidistant.

Null mutation in sspA of Cronobacter sakazakii influences its tolerance to environmental stress

2021 ◽  
Author(s):  
Jie Zhan ◽  
Xin Tan ◽  
Xiaoyuan Wang
Keyword(s):  
Stress Tolerance ◽  
Protein A ◽  
Bacterial Chemotaxis ◽  
Water Concentration ◽  
Acid Tolerance ◽  
Opportunistic Pathogen ◽  
Cronobacter Sakazakii ◽  
Knockout Mutant ◽  
Cellular Survival ◽  
E Coli

Cronobacter sakazakii is a known foodborne opportunistic pathogen that can affect the intestinal health of infants. Despite undergoing complex manufacturing processes and low water concentration in the finished product, infant formula has been associated with Cronobacter infections, suggesting that C. sakazakii’s pathogenicity may be related to its tolerance to stress. In this study, the effect of the stringent starvation protein A (SspA), which plays an important role in E. coli cellular survival under environmental stresses, on the stress tolerance of C. sakazakii BAA894 was investigated by creating an sspA-knockout mutant. The effects of this mutation on the acid, desiccation and drug tolerance were assessed, and results showed that acid tolerance decreased, while desiccation tolerance increased in LB and decreased in M9. Moreover, the MICs of 10 antibiotics in LB medium and 8 antibiotics in M9 medium were determined and compared of the wild-type and ΔsspA. Transcriptome analysis showed that 27.21% or 37.78% of the genes in ΔsspA were significantly differentially expressed in LB or M9 media, the genes relevant to microbial metabolism in diverse environments and bacterial chemotaxis were detailed analyzed. The current study contributes towards an improved understanding of the role of SspA in C. sakazakii BAA894 stress tolerance.

An Allosteric Model for Transmembrane Signaling in Bacterial Chemotaxis

2004 ◽  
Vol 343 (2) ◽  
pp. 291-303 ◽  
Author(s):  
Christopher V. Rao ◽  
Michael Frenklach ◽  
Adam P. Arkin
Keyword(s):  
Bacterial Chemotaxis ◽  
Transmembrane Signaling ◽  
Allosteric Model

scholarly journals The Semiotic Approach to Bacterial Chemotaxis

Biosemiotics ◽  
2021 ◽  
Author(s):  
Adam Kłóś ◽  
Przemysław Mieszko Płonka
Keyword(s):  
Molecular Level ◽  
Bacterial Chemotaxis ◽  
Population Level ◽  
General Process ◽  
E Coli ◽  
Bacterial Response ◽  
Semiotic Approach ◽  
Ultimate Nature ◽  
Cell Signaling Pathways

AbstractBacterial chemotaxis is often considered to be a textbook example of the rudimentary semiotic process. As such, it gives an excellent opportunity to better understand both semiosis and biology. Our study reviews this phenomenon in the light of up-to-date scientific knowledge to answer the most basic semiotic questions: what is the sign? What types of signs are there? What is the meaning understood on the molecular level, and by what means can it grow with time? As a case study, the bacterial chemotaxis toward glucose in E. coli species is chosen, and the semiotic framework of Charles Sanders Peirce applied. The analyses provide us with the following results: the sign, in its ultimate nature, is a general process. Bacterial chemotaxis can be understood in terms of Peircean type, symbol, and argument. The meaning on the molecular level is entirely pragmatic and, in this case, reduced to a bacterial response to glucose. A sign can grow through sign generalization, the emergence of different sign categories, the integration of these categories in functional cycles, and the introduction of contextuality. The sign of bacterial chemotaxis extends from the cell signaling pathways up to the population level. The presented results advance our knowledge of sign processing in the context of semiotic evolution.

scholarly journals Bacterial chemotaxis to saccharides is governed by a trade-off between sensing and uptake

2021 ◽  
Author(s):  
Noele Norris ◽  
Uria Alcolombri ◽  
Johannes M Keegstra ◽  
Yutaka Yawata ◽  
Filippo Menolascina ◽  
...  
Keyword(s):  
Bacterial Chemotaxis ◽  
Nutrient Concentrations ◽  
Trade Off ◽  
Agent Based ◽  
E Coli ◽  
High Affinity ◽  
Cytoplasmic Transport ◽  
Uptake Rates ◽  
Methyl Aspartate ◽  
Microfluidic Assays

To swim up gradients of nutrients, E. coli senses nutrient concentrations within its periplasm. For small nutrient molecules, periplasmic concentrations typically match extracellular concentrations. However, this is not necessarily the case for saccharides, such as maltose, which is transported into the periplasm via a specific porin. Previous observations have shown that under various conditions E. coli limits maltoporin abundance so that, for extracellular micromolar concentrations of maltose, there are predicted to be only nanomolar concentrations of free maltose in the periplasm. Thus, in the micromolar regime, the total uptake of maltose from the external environment into the cytoplasm is limited not by the abundance of cytoplasmic transport proteins but by the abundance of maltoporins. Here we present results from experiments and modeling showing that this porin-limited transport enables E. coli to sense micromolar gradients of maltose despite having a high-affinity ABC transport system that is saturated at these micromolar levels. We used microfluidic assays to study chemotaxis of E. coli in various gradients of maltose and methyl-aspartate and leveraged our experimental observations to develop a mechanistic transport-and-sensing chemotaxis model. Incorporating this model into agent-based simulations, we discover a trade-off between uptake and sensing: although high-affinity transport enables higher uptake rates at low nutrient concentrations, it severely limits dynamic sensing range. We thus propose that E. coli may limit periplasmic uptake to increase its chemotactic sensitivity, enabling it to use maltose as an environmental cue.

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 Effect of inoculum size and antibiotics on bacterial traveling bands in a thin microchannel defined by optical adhesive

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yang Liu ◽  
Thomas Lehnert ◽  
Martin A. M. Gijs
Keyword(s):  
Phenotypic Diversity ◽  
Swimming Performance ◽  
Effective Diffusion ◽  
Bacterial Chemotaxis ◽  
Microfluidic Channel ◽  
Adhesive Layer ◽  
Inoculum Size ◽  
E Coli ◽  
Optical Adhesive ◽  
The Impact

AbstractPhenotypic diversity in bacterial flagella-induced motility leads to complex collective swimming patterns, appearing as traveling bands with transient locally enhanced cell densities. Traveling bands are known to be a bacterial chemotactic response to self-generated nutrient gradients during growth in resource-limited microenvironments. In this work, we studied different parameters of Escherichia coli (E. coli) collective migration, in particular the quantity of bacteria introduced initially in a microfluidic chip (inoculum size) and their exposure to antibiotics (ampicillin, ciprofloxacin, and gentamicin). We developed a hybrid polymer-glass chip with an intermediate optical adhesive layer featuring the microfluidic channel, enabling high-content imaging of the migration dynamics in a single bacterial layer, i.e., bacteria are confined in a quasi-2D space that is fully observable with a high-magnification microscope objective. On-chip bacterial motility and traveling band analysis was performed based on individual bacterial trajectories by means of custom-developed algorithms. Quantifications of swimming speed, tumble bias and effective diffusion properties allowed the assessment of phenotypic heterogeneity, resulting in variations in transient cell density distributions and swimming performance. We found that incubation of isogeneic E. coli with different inoculum sizes eventually generated different swimming phenotype distributions. Interestingly, incubation with antimicrobials promoted bacterial chemotaxis in specific cases, despite growth inhibition. Moreover, E. coli filamentation in the presence of antibiotics was assessed, and the impact on motility was evaluated. We propose that the observation of traveling bands can be explored as an alternative for fast antimicrobial susceptibility testing.

Biological Circuit Components

2014 ◽  
Author(s):  
Richard M. Murray
Keyword(s):  
Synthetic Biology ◽  
Bacterial Chemotaxis ◽  
Dynamical Model ◽  
Genetic Circuit ◽  
Toggle Switch ◽  
Simple Circuit ◽  
Natural Systems ◽  
E Coli ◽  
Feedforward Loop ◽  
Circuit Components

This chapter describes some simple circuit components that have been constructed in E. coli cells using the technology of synthetic biology and then considers a more complicated circuit that already appears in natural systems to implement adaptation. It first analyzes the negatively autoregulated gene fabricated in E. coli bacteria, before turning to the toggle switch, which is composed of two genes that mutually repress each other. The chapter next illustrates a dynamical model of a “repressilator”—an oscillatory genetic circuit consisting of three repressors arranged in a ring fashion. The activator–repressor clock is then considered, alongside an incoherent feedforward loop (IFFL). Finally, the chapter examines bacterial chemotaxis, which E. coli use to move in the direction of increasing nutrients.

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