Featured Research

from universities, journals, and other organizations

DNA Throttle Controls Molecular Machine

Date:
September 5, 2003
Source:
University Of California - Davis
Summary:
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.

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.

Related Articles


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.


Story Source:

The above story is based on materials provided by University Of California - Davis. Note: Materials may be edited for content and length.


Cite This Page:

University Of California - Davis. "DNA Throttle Controls Molecular Machine." ScienceDaily. ScienceDaily, 5 September 2003. <www.sciencedaily.com/releases/2003/09/030905072455.htm>.
University Of California - Davis. (2003, September 5). DNA Throttle Controls Molecular Machine. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2003/09/030905072455.htm
University Of California - Davis. "DNA Throttle Controls Molecular Machine." ScienceDaily. www.sciencedaily.com/releases/2003/09/030905072455.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Christmas Kissing Good for Health

Christmas Kissing Good for Health

Reuters - Innovations Video Online (Dec. 22, 2014) Scientists in Amsterdam say couples transfer tens of millions of microbes when they kiss, encouraging healthy exposure to bacteria. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Brain-Dwelling Tapeworm Reveals Genetic Secrets

Brain-Dwelling Tapeworm Reveals Genetic Secrets

Reuters - Innovations Video Online (Dec. 22, 2014) Cambridge scientists have unravelled the genetic code of a rare tapeworm that lived inside a patient's brain for at least four year. Researchers hope it will present new opportunities to diagnose and treat this invasive parasite. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Earthworms Provide Cancer-Fighting Bacteria

Earthworms Provide Cancer-Fighting Bacteria

Reuters - Innovations Video Online (Dec. 21, 2014) Polish scientists isolate bacteria from earthworm intestines which they say may be used in antibiotics and cancer treatments. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins