A Simple Explanation of the Electrostatics of the B-to-Z Transition of DNA

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 89; no. 13; pp. 5740 - 5743
• Main Authors: Gueron, M., J.-P. Demaret
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.07.1992; National Acad Sciences; National Academy of Sciences
• Subjects: Biological and medical sciences; Charge density; Conformational dynamics in molecular biology; Cylinders; Deoxyribonucleic acid; DNA; DNA - chemistry; Electric fields; Electrochemistry; Electrostatics; Free energy; Fundamental and applied biological sciences. Psychology; Ions; Molecular biophysics; Nucleic Acid Conformation; Parametric models; Phosphates; Phosphates - chemistry; Salts; Static electricity; Thermodynamics; Z form DNA; Z DNA; Models; Stability; Electrostatic properties; Conformation; Conformational transition
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.13.5740

Whereas the phosphates of B-DNA jut out into the solution, those of Z-DNA, being closer to DNA matter, are less subject to electrostatic screening by counterions. We present simple planar models of B- and Z-DNA that reflect these geometric features. The ionic strength dependence of the difference in the Poisson-Boltzmann electrostatic free energy of the models agrees with that measured by Pohl [Pohl, F. M. (1983) Cold Spring Harbor Symp. Quant. Biol. 47, 113-118]. This indicates that the electrostatics of the B-to-Z transition are primarily controlled by a qualitative geometrical difference and not by details of the DNA geometry or by complex electrostatic properties of the ionic solution.