Intersegmental interactions in supercoiled DNA: Atomic force microscope study

Luda S. Shlyakhtenko, Lela Miloseska, Vladimir N. Potaman, Richard R. Sinden, Yuri L. Lyubchenko

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Intersegmental interactions in DNA facilitated by the neutralization of electrostatic repulsion was studied as a function of salt concentration and DNA supercoiling. DNA samples with defined superhelical densities were deposited onto aminopropyl mica at different ionic conditions and imaged in air after drying of the samples. Similar to hydrodynamic data, we did not observe a collapse of supercoiled DNA, as proposed earlier by cryo-EM studies. Instead, the formation of the contacts between DNA helices within supercoiled loops with no visible space between the duplexes was observed. The length of such close contacts increased upon increasing NaCl concentration. DNA supercoiling was a critical factor for the stabilization of intersegmental contacts. Implications of the observed effect for understanding DNA compaction in the cell and for regulation DNA transactions via interaction of distantly separated DNA regions are discussed.

Original languageEnglish (US)
Pages (from-to)263-270
Number of pages8
JournalUltramicroscopy
Volume97
Issue number1-4
DOIs
StatePublished - 2003

Keywords

  • AFM
  • DNA supercoiling
  • Silanes
  • Surface functionalization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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