Issue 16, 2018

Probing the propeller-like loops of DNA G-quadruplexes with looped-out 2-aminopurine for label-free switchable molecular sensing

Abstract

We report a new signal readout mechanism for DNA molecular sensing devices using ligand-free fluorogenic G-quadruplexes in which the propeller-like loops are distinguished from the diagonal and lateral loops with incorporated 2-aminopurine (2-AP, a fluorescent analogue of adenine). We study the fluorescence behavior of looped-out 2-AP in duplexes and G-quadruplexes and demonstrate that it shows better fluorescence properties in shorter loops. In particular, 2-AP in the propeller-like loops of parallel or hybrid G-quadruplexes displays a perfect fluorescence emission whereas that in the diagonal and lateral loops does not. This loop-environment-sensitive feature allows 2-AP to probe the propeller-like loops of G-quadruplexes, illustrated by an ion-tuned allosteric G-quadruplex FG9A and a (3 + 1) hybrid human telomeric DNA. In the presence of K+, FG9A folds into a parallel structure where 2-AP is in the propeller-like loops and shows a high fluorescence signal, which can probe K+ concentrations down to 25 μM. Upon addition of Pb2+, the folded FG9A converts into an antiparallel structure which is revealed by a sharp decrease in 2-AP fluorescence, which can easily be reset with EDTA. This process is utilized to reversibly sense Pb2+ with a detection limit of 100 nM. Furthermore, its ability to probe the propeller-like loops may allow 2-AP to identify the folding topologies of unknown G-quadruplexes in human gene regions.

Graphical abstract: Probing the propeller-like loops of DNA G-quadruplexes with looped-out 2-aminopurine for label-free switchable molecular sensing

Supplementary files

Article information

Article type
Paper
Submitted
17 May 2018
Accepted
21 Jun 2018
First published
22 Jun 2018

Analyst, 2018,143, 3814-3820

Probing the propeller-like loops of DNA G-quadruplexes with looped-out 2-aminopurine for label-free switchable molecular sensing

P. Peng, Y. Du, Y. Sun, S. Liu, L. Mi and T. Li, Analyst, 2018, 143, 3814 DOI: 10.1039/C8AN00914G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements