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 Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Quantum material is promising 'ion conductor' for research, new technologies

17.08.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>