Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

DNA throttle controls molecular machine

05.09.2003


A DNA sequence that acts as a throttle to control the rate at which an enzyme moves along the DNA has been observed by researchers at UC Davis. By controlling the activity of the RecBCD helicase enzyme, the "Chi" sequence can affect how efficiently genes are repaired.

RecBCD unwinds the DNA double helix so that the genetic code can be read, copied or repaired. This unwinding is an essential first step in most processes involving DNA.

The research findings, which are published in the September 5 issue of the journal Cell, could explain how short DNA sequences such as Chi can interact with enzymes and affect how DNA is copied or repaired. They could also give insight into how to control the speed of tiny nanomachines built for various purposes.



The enzyme moves along DNA at a rate of up to 1000 base pairs a second. Using special apparatus to film single enzymes at work in real time, the UC Davis researchers found that when RecBCD reaches the eight-letter Chi sequence, it stops for up to 10 seconds and then carries on at half speed.

The researchers attached DNA molecules labeled with a fluorescent dye to polystyrene beads one-millionth of a millimeter in size. Under the microscope, the bead looks like a white sphere with a bright string of DNA attached.

The researchers were postdoctoral scholars Maria Spies, Piero Bianco, Mark Dillingham and Naofumi Handa with Stephen Kowalczykowski, professor of microbiology and director of the UC Davis Center for Genes and Development, and Ronald Baskin, professor of molecular and cell biology.

They let RecBCD attach to the free end of the DNA strand, and used laser beams as "optical tweezers" to move the beads into position under a microscope.

As RecBCD unwinds the DNA strands, the fluorescent dye is removed, so the bright string of DNA appears to shorten.

When the researchers put RecBCD onto DNA molecules carrying the Chi sequence, they found that RecBCD stops for up to 10 seconds when it reaches the beginning of the Chi sequence, then continues at a slower rate.

"It’s a complete surprise," Kowalczykowski said. The results would have been impossible to find with a conventional bulk experiment averaging the activity of many enzymes and DNA molecules, he said.

RecBCD is a molecular machine made up of three proteins. Two of these are motor units that propel the enzyme along the DNA double helix. Kowalczykowski believes that the change in velocity is due to one of two motor subunits in RecBCD being switched off by the Chi sequence.

The Chi sequence is known to be associated with "hotspots" where genes are readily exchanged, or recombined, between chromosomes.


Media contact:
Andy Fell, UC Davis News Service, (530) 752-4533, ahfell@ucdavis.edu

Andy Fell | UC Davis
Further information:
http://www.news.ucdavis.edu/search/news_detail.lasso?id=6671

More articles from Life Sciences:

nachricht For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>