Open AccessSupercoiling-dependent flexibility of adenosine-tract-containing DNA detected by a topological method
Author(s) -
Hua Tsen,
Stephen D. Levene
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.7.2817
Subject(s) - dna supercoil , dna , topology (electrical circuits) , hmg box , bent molecular geometry , biology , plasmid , biophysics , chemistry , microbiology and biotechnology , genetics , gene , dna binding protein , transcription factor , dna replication , mathematics , organic chemistry , combinatorics
Intrinsically bent DNA sequences have been implicated in the activation of transcription by promoting juxtaposition of DNA sequences near the terminal loop of a superhelical domain. We have developed a novel topological assay for DNA looping based on λ integrative recombination to study the effects of intrinsically bent DNA sequences on the tertiary structure of negatively supercoiled DNA. Remarkably, the localization of adenosine-tract (A-tract) sequences in the terminal loop of a supercoiled plasmid is independent of the extent of intrinsic bending. The results suggest that A-tract-containing sequences have other properties that organize the structure of superhelical domains apart from intrinsic bending and may explain the lack of conservation in the degree of A-tract-dependent bending among DNA sequences located upstream of bacterial promoters.