Cation charge dependence of the forces driving DNA assembly

Jason DeRouchey, V. Adrian Parsegian, Donald C. Rau

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Understanding the strength and specificity of interactions among biologically important macromolecules that control cellular functions requires quantitative knowledge of intermolecular forces. Controlled DNA condensation and assembly are particularly critical for biology, with separate repulsive and attractive intermolecular forces determining the extent of DNA compaction. How these forces depend on the charge of the condensing ion has not been determined, but such knowledge is fundamental for understanding the basis of DNA-DNA interactions. Here, we measure DNA force-distance curves for a homologous set of arginine peptides. All forces are well fit as the sum of two exponentials with 2.4- and 4.8-Å decay lengths. The shorter-decay-length force is always repulsive, with an amplitude that varies slightly with length or charge. The longerdecay- length force varies strongly with cation charge, changing from repulsion with Arg1 to attraction with Arg2. Force curves for a series of homologous polyamines and the heterogeneous protein protamine are quite similar, demonstrating the universality of these forces for DNA assembly. Repulsive amplitudes of the shorter-decay-length force are species-dependent but nearly independent of charge within each species. A striking observation was that the attractive force amplitudes for all samples collapse to a single curve, varying linearly with the inverse of the cation charge.

Original languageEnglish
Pages (from-to)2608-2615
Number of pages8
JournalBiophysical Journal
Volume99
Issue number8
DOIs
StatePublished - Oct 20 2010

Bibliographical note

Funding Information:
This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health.

ASJC Scopus subject areas

  • Biophysics

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