Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stretching DNA on a tiny scale, researchers probe the basis for its compaction

23.04.2004


Using magnets and video microscopy to measure the length of individual DNA molecules under experimental conditions, researchers have demonstrated that Condensin, a complex of proteins widely conserved in evolution, physically compacts DNA in a manner dependent on energy from ATP. The finding is significant because the Condensin complex, which is essential for life, has been known to play a key role in the dramatic condensation of genomic DNA that precedes mitosis and cell division. The new work puts into sharper focus the mechanism by which Condensin accomplishes this compaction, which is essential for the precise segregation of the genetic material to later generations of cells.



Scientists Terence Strick, Tatsuhiko Kawaguchi and Tatsuya Hirano of Cold Spring Harbor Laboratory employed a nanomanipulation technique by which small individual molecules of DNA, tethered on one end to a glass slide and attached on the other end to a magnetic bead, could be gently stretched and twisted using small magnets. The technique allowed the researchers to exert controlled, variable force on the extended DNA, directly measuring changes in its compaction following interactions with Condensin complexes isolated from frog eggs. Because the helical DNA could be twisted, the scientists were also able to investigate how DNA topology – in this case, topological states called positive and negative supercoiling – might affect its ability to be compacted by Condensin. Such measurements are central to illuminating the molecular mechanism used by Condensin in the cell.

The researchers found that Condensin compacts DNA against a weak stretching force, but that increasing the force on the DNA reversed compaction, effectively breaking apart the molecular interactions formed by Condensin. Carefully measuring changes in distance between the two ends of the DNA molecule revealed evidence that both compaction and decompaction often occurred in jumps of certain lengths. Comparing the range of these step sizes to the physical dimensions of Condensin complexes, the authors were able to make some informed proposals for how Condensins interact with DNA – for example, by forming large DNA loops that can be popped open by increased stretching force. It remains unclear whether individual Condensin complexes can accomplish this task single-handedly, or whether multiple complexes act cooperatively, but the new findings and techniques employed here establish a solid foundation for further work on such questions.



Terence R. Strick, Tatsuhiko Kawaguchi and Tatsuya Hirano: "Real-time Detection of Single-molecule DNA Compaction by Condensin I"

Published online in Current Biology 22 April 2004. Appearing in print in Current Biology Volume 14, Number 10, 25 May 2004.

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com/

More articles from Life Sciences:

nachricht Scientists spin artificial silk from whey protein
24.01.2017 | Deutsches Elektronen-Synchrotron DESY

nachricht Choreographing the microRNA-target dance
24.01.2017 | UT Southwestern Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>