Stretching DNA to the limit

April 24, 2007

It has long been known that UV light can damage DNA, reducing its ability to replicate and interact with proteins, and often resulting in the development of skin cancers. However, not much is known about how the elasticity of DNA strands is altered upon exposure to UV light. Now a group of researchers at Duke University have developed a method to measure changes in the mechanical properties of DNA upon irradiation with UV light.

Piotr Marszalek and his colleagues have conducted single-molecule force spectroscopy measurements on viral DNA, which show the unraveling of the DNA double helix upon exposure to UV irradiation. The researchers essentially pick up individual DNA molecules with the tip of a scanning probe microscope and stretch it while measuring the forces generated. These "stretch--release" measurements enable the accurate determination of changes in the elasticity of the DNA strands. Upon exposure to UV light, the force profile of the viral DNA changes dramatically in a dose-dependent manner. The force curve of intact DNA is characterized by a plateau region. This characteristic plateau is drastically reduced in width with increasing exposure to UV light.

UV light induces the crosslinking of the constituent DNA bases within the polynucleotide chains, as well as causes the formation of lesions by linking together the adjacent strands. The small changes in structure induced by this crosslinking can very profoundly affect the ability of DNA to recognize specific molecules, and can thus completely disrupt its ability to replicate and interact with the transcriptional machinery to synthesize proteins. Marszalek and his colleagues have also examined synthetic DNA to figure out the extent to which different bases are affected by UV light. They conclude that the changes in the force profile of viral DNA exposed to UV light are due to the local unwinding of the double helix in some regions arising from the massive formation of crosslinked structures.

"These are the first measurements that establish a relationship between DNA nanomechanics and damage", said Marszalek. He believes that this work paves the way for using stretch--release force spectroscopy measurements in DNA diagnostics.
-end-
Autor: Piotr E. Marszalek, Duke University (USA), http://www.mems.duke.edu/faculty/marszalek/index.php

Small 2007, 3, No. 5, doi: 10.1002/smll.200600592

About Small: Micro and Nano: No small Matter. Science at the nano- and microscale is currently receiving enormous wordwide interest. Published by Wiley-VCH, Small provides the very best forum for experimental and theoretical studies of fundamental and applied interdisciplinary research at these dimensions. Read an attractive mix of peer-reviewed Communications, Reviews, Concepts, Highlights, Essays, and Full Papers.

Wiley

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.