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Article Dans Une Revue Nucleic Acids Research Année : 2021

Local structure of DNA toroids reveals curvature-dependent intermolecular forces

Résumé

In viruses and cells, DNA is closely packed and tightly curved thanks to polyvalent cations inducing an effective attraction between its negatively charged filaments. Our understanding of this effective attraction remains very incomplete, partly because experimental data is limited to bulk measurements on large samples of mostly uncurved DNA helices. Here we use cryo electron microscopy to shed light on the interaction between highly curved helices. We find that the spacing between DNA helices in spermineinduced DNA toroidal condensates depends on their location within the torus, consistent with a mathematical model based on the competition between electrostatic interactions and the bending rigidity of DNA. We use our model to infer the characteristics of the interaction potential, and find that its equilibrium spacing strongly depends on the curvature of the filaments. In addition, the interaction is much softer than previously reported in bulk samples using different salt conditions. Beyond viruses and cells, our characterization of the interactions governing DNAbased dense structures could help develop robust designs in DNA nanotechnologies.
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Dates et versions

hal-03440063 , version 1 (22-11-2021)

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Luca Barberi, Françoise Livolant, Amélie Leforestier, Martin Lenz. Local structure of DNA toroids reveals curvature-dependent intermolecular forces. Nucleic Acids Research, 2021, 49 (7), pp.3709 - 3718. ⟨10.1093/nar/gkab197⟩. ⟨hal-03440063⟩
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