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 If Machines Could Smell ...
19.07.2019 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

nachricht Algae-killing viruses spur nutrient recycling in oceans
18.07.2019 | Rutgers University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Heat flow through single molecules detected

19.07.2019 | Physics and Astronomy

Heat transport through single molecules

19.07.2019 | Physics and Astronomy

Welcome Committee for Comets

19.07.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>