Dependence of DNA Persistence Length on Ionic Strength and Ion Type

Sébastien Guilbaud (1) , Laurence Salomé (1) , Nicolas Destainville (2, 3) , Manoel Manghi (2) , Catherine Tardin (1)

1 IPBS - Institut de pharmacologie et de biologie structurale
2 PhyStat - Physique Statistique des Systèmes Complexes (LPT)
3 LPT - Laboratoire de Physique Théorique

Even though the persistence length L P of double-stranded DNA plays a pivotal role in cell biology and nanotechnologies, its dependence on ionic strength I lacks a consensual description. Using a high-throughput single-molecule technique and statistical physics modeling, we measure LP in the presence of monovalent (Li + , Na + , K +) and divalent (Mg 2+ , Ca 2+) metallic and alkyl ammonium ions, over a large range 0.5 mM ≤ I ≤ 5 M. We show that linear Debye-Hückel-type theories do not describe even part of these data. By contrast, the Netz-Orland and Trizac-Shen formulas, two approximate theories including nonlinear electrostatic effects and the finite DNA radius, fit our data with divalent and monovalent ions, respectively, over the whole I range. Furthermore, the metallic ion type does not influence LP(I), in contrast to alkyl ammonium monovalent ions at high I. PHYSICAL REVIEW LETTERS 122, 028102 (2019) 0031-9007=19=122(2)=028102(6) 028102-1

Domaines: Biophysique [physics.bio-ph]

Sébastien Guilbaud, Laurence Salomé, Nicolas Destainville, Manoel Manghi, Catherine Tardin. Dependence of DNA Persistence Length on Ionic Strength and Ion Type. Physical Review Letters, 2019, 122 (2), pp.028102. ⟨10.1103/PhysRevLett.122.028102⟩. ⟨hal-02024889⟩