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Understanding the link between single cell and population scale responses of Escherichia coli in differing ligand gradients.

Edgington MP, Tindall MJ - Comput Struct Biotechnol J (2015)

Bottom Line: We then study the response of cells in the presence of two different chemoattractants.In doing so we demonstrate that the population scale response depends not on the absolute concentration of each chemoattractant but on the sensitivity of the chemoreceptors to their respective concentrations.Our results show the clear link between single cell features and the overall environment in which cells reside.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematics & Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX, UK.

ABSTRACT
We formulate an agent-based population model of Escherichia coli cells which incorporates a description of the chemotaxis signalling cascade at the single cell scale. The model is used to gain insight into the link between the signalling cascade dynamics and the overall population response to differing chemoattractant gradients. Firstly, we consider how the observed variation in total (phosphorylated and unphosphorylated) signalling protein concentration affects the ability of cells to accumulate in differing chemoattractant gradients. Results reveal that a variation in total cell protein concentration between cells may be a mechanism for the survival of cell colonies across a wide range of differing environments. We then study the response of cells in the presence of two different chemoattractants. In doing so we demonstrate that the population scale response depends not on the absolute concentration of each chemoattractant but on the sensitivity of the chemoreceptors to their respective concentrations. Our results show the clear link between single cell features and the overall environment in which cells reside.

No MeSH data available.


Related in: MedlinePlus

MeAsp and serine bind with strong affinity to Tar and Tsr chemoreceptors, respectively. Additionally, MeAsp is able to bind Tsr chemoreceptors with a low affinity, as seen in panel (A). Panel (B) is reproduced from the work of Mello & Tu [15] and illustrates the difference in the sensitivity of a receptor complex when MeAsp may bind only to Tar receptors (blue) and where the low affinity binding of MeAsp to Tsr chemoreceptors is considered (red). In this work, the low affinity binding of MeAsp to Tsr chemoreceptors is neglected due to the chemoattractant concentrations considered. Note that sensitivity is defined as S≡ − ∂lnΦ/∂ ln[L], where S denotes the sensitivity, Φ is the receptor signalling team activity and [L] represents the ligand concentration. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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f0010: MeAsp and serine bind with strong affinity to Tar and Tsr chemoreceptors, respectively. Additionally, MeAsp is able to bind Tsr chemoreceptors with a low affinity, as seen in panel (A). Panel (B) is reproduced from the work of Mello & Tu [15] and illustrates the difference in the sensitivity of a receptor complex when MeAsp may bind only to Tar receptors (blue) and where the low affinity binding of MeAsp to Tsr chemoreceptors is considered (red). In this work, the low affinity binding of MeAsp to Tsr chemoreceptors is neglected due to the chemoattractant concentrations considered. Note that sensitivity is defined as S≡ − ∂lnΦ/∂ ln[L], where S denotes the sensitivity, Φ is the receptor signalling team activity and [L] represents the ligand concentration. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Mentions: E. coli receptor clusters contain up to five different receptor types which are able to respond to a range of chemoattractants. Tar and Tsr are the two most abundant, which respond to methyl–aspartate (MeAsp) in the case of Tar and Tsr, and serine, in the case of Tsr. However, the Tsr response to MeAsp is neglible for small to intermediate attractant concentrations. Receptor sensitivity to such attractants has been an active area of research which has demonstrated the clear link between receptor occupation and thus sensitivity to differing ligand concentrations [15] as shown in Fig. 2(b).


Understanding the link between single cell and population scale responses of Escherichia coli in differing ligand gradients.

Edgington MP, Tindall MJ - Comput Struct Biotechnol J (2015)

MeAsp and serine bind with strong affinity to Tar and Tsr chemoreceptors, respectively. Additionally, MeAsp is able to bind Tsr chemoreceptors with a low affinity, as seen in panel (A). Panel (B) is reproduced from the work of Mello & Tu [15] and illustrates the difference in the sensitivity of a receptor complex when MeAsp may bind only to Tar receptors (blue) and where the low affinity binding of MeAsp to Tsr chemoreceptors is considered (red). In this work, the low affinity binding of MeAsp to Tsr chemoreceptors is neglected due to the chemoattractant concentrations considered. Note that sensitivity is defined as S≡ − ∂lnΦ/∂ ln[L], where S denotes the sensitivity, Φ is the receptor signalling team activity and [L] represents the ligand concentration. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660157&req=5

f0010: MeAsp and serine bind with strong affinity to Tar and Tsr chemoreceptors, respectively. Additionally, MeAsp is able to bind Tsr chemoreceptors with a low affinity, as seen in panel (A). Panel (B) is reproduced from the work of Mello & Tu [15] and illustrates the difference in the sensitivity of a receptor complex when MeAsp may bind only to Tar receptors (blue) and where the low affinity binding of MeAsp to Tsr chemoreceptors is considered (red). In this work, the low affinity binding of MeAsp to Tsr chemoreceptors is neglected due to the chemoattractant concentrations considered. Note that sensitivity is defined as S≡ − ∂lnΦ/∂ ln[L], where S denotes the sensitivity, Φ is the receptor signalling team activity and [L] represents the ligand concentration. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Mentions: E. coli receptor clusters contain up to five different receptor types which are able to respond to a range of chemoattractants. Tar and Tsr are the two most abundant, which respond to methyl–aspartate (MeAsp) in the case of Tar and Tsr, and serine, in the case of Tsr. However, the Tsr response to MeAsp is neglible for small to intermediate attractant concentrations. Receptor sensitivity to such attractants has been an active area of research which has demonstrated the clear link between receptor occupation and thus sensitivity to differing ligand concentrations [15] as shown in Fig. 2(b).

Bottom Line: We then study the response of cells in the presence of two different chemoattractants.In doing so we demonstrate that the population scale response depends not on the absolute concentration of each chemoattractant but on the sensitivity of the chemoreceptors to their respective concentrations.Our results show the clear link between single cell features and the overall environment in which cells reside.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematics & Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX, UK.

ABSTRACT
We formulate an agent-based population model of Escherichia coli cells which incorporates a description of the chemotaxis signalling cascade at the single cell scale. The model is used to gain insight into the link between the signalling cascade dynamics and the overall population response to differing chemoattractant gradients. Firstly, we consider how the observed variation in total (phosphorylated and unphosphorylated) signalling protein concentration affects the ability of cells to accumulate in differing chemoattractant gradients. Results reveal that a variation in total cell protein concentration between cells may be a mechanism for the survival of cell colonies across a wide range of differing environments. We then study the response of cells in the presence of two different chemoattractants. In doing so we demonstrate that the population scale response depends not on the absolute concentration of each chemoattractant but on the sensitivity of the chemoreceptors to their respective concentrations. Our results show the clear link between single cell features and the overall environment in which cells reside.

No MeSH data available.


Related in: MedlinePlus