Affordable Access

deepdyve-link deepdyve-link
Publisher Website

Quantification of topological coupling between DNA superhelicity and G-quadruplex formation.

Authors
  • Selvam, Sangeetha
  • Koirala, Deepak
  • Yu, Zhongbo
  • Mao, Hanbin
Type
Published Article
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society
Publication Date
Oct 08, 2014
Volume
136
Issue
40
Pages
13967–13970
Identifiers
DOI: 10.1021/ja5064394
PMID: 25216033
Source
Medline
License
Unknown

Abstract

It has been proposed that new transcription modulations can be achieved via topological coupling between duplex DNA and DNA secondary structures, such as G-quadruplexes, in gene promoters through superhelicity effects. Limited by available methodologies, however, such a coupling has not been quantified directly. In this work, using novel magneto-optical tweezers that combine the nanometer resolution of optical tweezers and the easy manipulation of magnetic tweezers, we found that the flexibility of DNA increases with positive superhelicity (σ). More interestingly, we found that the population of G-quadruplex increases linearly from 2.4% at σ = 0.1 to 12% at σ = -0.03. The population then rapidly increases to a plateau of 23% at σ < -0.05. The rapid increase coincides with the melting of double-stranded DNA, suggesting that G-quadruplex formation is correlated with DNA melting. Our results provide evidence for topology-mediated transcription modulation at the molecular level. We anticipate that these high-resolution magneto-optical tweezers will be instrumental in studying the interplay between the topology and activity of biological macromolecules from a mechanochemical perspective.

Report this publication

Statistics

Seen <100 times