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The electrostatic origin of low-hydration polymorphism in DNA.
1CNRS UPR9080, Institut de Biologie Physico-Chimique, 13, rue Pierre et Marie Curie, Paris, France. alexey@ibpc.fr
Summary
Low-hydration polymorphism in double-helical DNA arises from water
Area of Science:
- Biophysics
- Structural Biology
- Physical Chemistry
Background:
- Significant advancements have been made in understanding the physical mechanisms behind low-hydration polymorphism in double-helical DNA.
- This phenomenon is observed across various biological systems and is linked to water's capacity to form extensive hydrogen-bonded networks.
Purpose of the Study:
- To propose a universal electrostatic mechanism for low-hydration polymorphism in DNA.
- To explain the transition from a hydrated state to condensed DNA structures at low water concentrations.
Main Methods:
- Conceptual analysis of water's role in DNA structural transitions.
- Exploration of percolation theory in the context of biomacromolecule hydration.
- Examination of electrostatic interactions and dielectric properties of water at low hydration levels.
Main Results:
- Water forms spanning hydrogen-bonded networks around DNA via a quasi-two-dimensional percolation transition.
- Disintegration of this network below the percolation threshold causes DNA condensation.
- This occurs because water's dielectric permittivity decreases, while counterion concentration increases.
Conclusions:
- A simple electrostatic mechanism is proposed as the universal origin of low-hydration polymorphism in DNA.
- This mechanism explains DNA strand condensation due to changes in water's properties and counterion behavior.
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