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Chemophoresis as a driving force for intracellular organization: Theory and application to plasmid partitioning

View Article: PubMed Central - PubMed

ABSTRACT

Biological units such as macromolecules, organelles, and cells are directed to a proper location by gradients of chemicals. We consider a macroscopic element with surface binding sites where chemical adsorption reactions can occur and show that a thermodynamic force generated by chemical gradients acts on the element. By assuming local equilibrium and adopting the grand potential used in thermodynamics, we derive a formula for the “chemophoresis” force, which depends on chemical potential gradients and the Langmuir isotherm. The conditions under which the formula is applicable are shown to occur in intracellular reactions. Further, the role of the chemophoresis in the partitioning of bacterial chromosomal loci/plasmids during cell division is discussed. By performing numerical simulations, we demonstrate that the chemophoresis force can contribute to the regular positioning of plasmids observed in experiments.

No MeSH data available.


Schematic representation of our system. A bead is placed at r = ξ, and it moves in a d-dimensional space (d = 1, 2, 3). The adsorption reaction  occurs on the surface of the bead.
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f1-7_77: Schematic representation of our system. A bead is placed at r = ξ, and it moves in a d-dimensional space (d = 1, 2, 3). The adsorption reaction occurs on the surface of the bead.

Mentions: Consider organelles or macromolecules that have a number of binding sites on their surface for reactions to occur; for example, nucleoprotein complexes (NCs) have several promoter sites to bind transcription factors. Let us model these biological elements simply as beads with several reaction sites to which molecules attach themselves, as shown in Figure 1. The bead is placed at r = ξ and moves in a d-dimensional space r ∈ Rd (d = 1, 2, 3). We consider an isothermal process that is homogeneous over space at a given temperature T. We also consider a chemical bath containing a chemical X with a spatially dependent concentration x(r) or, equivalently, the corresponding chemical potential μ(r). This gradient is assumed to be sustained externally. A molecule of X is attached to a binding site B on the bead and forms a complex Y (Fig. 1), as given by the reaction


Chemophoresis as a driving force for intracellular organization: Theory and application to plasmid partitioning
Schematic representation of our system. A bead is placed at r = ξ, and it moves in a d-dimensional space (d = 1, 2, 3). The adsorption reaction  occurs on the surface of the bead.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036777&req=5

f1-7_77: Schematic representation of our system. A bead is placed at r = ξ, and it moves in a d-dimensional space (d = 1, 2, 3). The adsorption reaction occurs on the surface of the bead.
Mentions: Consider organelles or macromolecules that have a number of binding sites on their surface for reactions to occur; for example, nucleoprotein complexes (NCs) have several promoter sites to bind transcription factors. Let us model these biological elements simply as beads with several reaction sites to which molecules attach themselves, as shown in Figure 1. The bead is placed at r = ξ and moves in a d-dimensional space r ∈ Rd (d = 1, 2, 3). We consider an isothermal process that is homogeneous over space at a given temperature T. We also consider a chemical bath containing a chemical X with a spatially dependent concentration x(r) or, equivalently, the corresponding chemical potential μ(r). This gradient is assumed to be sustained externally. A molecule of X is attached to a binding site B on the bead and forms a complex Y (Fig. 1), as given by the reaction

View Article: PubMed Central - PubMed

ABSTRACT

Biological units such as macromolecules, organelles, and cells are directed to a proper location by gradients of chemicals. We consider a macroscopic element with surface binding sites where chemical adsorption reactions can occur and show that a thermodynamic force generated by chemical gradients acts on the element. By assuming local equilibrium and adopting the grand potential used in thermodynamics, we derive a formula for the “chemophoresis” force, which depends on chemical potential gradients and the Langmuir isotherm. The conditions under which the formula is applicable are shown to occur in intracellular reactions. Further, the role of the chemophoresis in the partitioning of bacterial chromosomal loci/plasmids during cell division is discussed. By performing numerical simulations, we demonstrate that the chemophoresis force can contribute to the regular positioning of plasmids observed in experiments.

No MeSH data available.