Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Proteins barge in to turn off unneeded genes and save energy

Provided/Chen Lab
A few Angstroms make all the difference. The CueR protein binds to DNA at the start of a gene that protects against copper poisoning. When copper atoms bind to CueR, the protein changes shape just enough to twist the DNA - such a small distance that it can't be drawn in two dimensions - to turn on transcription of the gene. When the gene is no longer needed, the original form of CueR unceremoniously kicks the copper-bound form away, turning off transcription quickly to save energy.
Provided/Chen Lab

A few Angstroms make all the difference. The CueR protein binds to DNA at the start of a gene that protects against copper poisoning. When copper atoms bind to CueR, the protein changes shape just enough to twist the DNA - such a small distance that it can't be drawn in two dimensions - to turn on transcription of the gene. When the gene is no longer needed, the original form of CueR unceremoniously kicks the copper-bound form away, turning off transcription quickly to save energy.

Abstract:
The sorcerer's apprentice started a water-carrying system, but couldn't stop it, and soon he was up to his neck in water, and trouble. Living cells have a better design: When they activate a gene, they have a system in reserve to turn it off. The cell does not want to waste energy making proteins it no longer needs. Cornell researchers have identified two mechanisms cells use and found they are designed to be quick.

Proteins barge in to turn off unneeded genes and save energy

Ithaca, NY | Posted on September 6th, 2012

Peng Chen, associate professor of chemistry and chemical biology, and colleagues report the discovery in the online edition of the Proceedings of the National Academy of Sciences Sept. 4. "The generic is for the activator to fall off, then the repressor binds," Chen said. "What we have found is two pathways that are much more efficient."

The work was done in bacteria and could lead to new ways to kill harmful bacteria, Chen said. It also represents a step forward in understanding gene transcription regulation that could apply further up the evolutionary ladder.

The biochemical processes involved take place on the scale of single molecules, far too small to observe through a microscope. To monitor these processes, the researchers tagged proteins and DNA binding sites with molecules that fluoresce and change their fluorescence intensity when they meet, so that a flash of light appears or changes when a biochemical reaction takes place. The fluorescence change is triggered by a rearrangement of electric charges as the tagging molecules come together, beginning when they are near (a matter of nanometers) and becoming brighter as they close in. By tagging one end of a protein molecule, the researchers can tell by the brightness of the signal which orientation the protein takes in binding to DNA.

The researchers worked with bacteria for which copper is toxic. These bacteria possess genes that code for a protein that grabs copper atoms and shoves them out through the cell wall. Ordinarily a protein called CueR binds to the chromosome in front of the sites of these genes and distorts the DNA, preventing the gene from being transcribed. When copper atoms bind to CueR it changes its configuration, allowing enzymes to transcribe the genes to make the protective proteins.

When the copper threat is gone another form of CueR, circulating in solution in the cell, replaces the copper-modified form, turning off the gene. By watching and timing the reactions, the Cornell researchers determined that the turnoff protein either shoves the bound protein out of the way or "assists" it in detaching and then moves into the vacant space. These mechanisms are up to 70 times faster than waiting for the activator to go away on its own, the research showed. It is likely that bacteria use similar methods for turning off protection against other toxic metals, they said.

The study also showed that the CueR protein can bind to the DNA in two different orientations and can spontaneously flip between them without completely detaching. In one orientation it binds only at the specific gene it is supposed to control. In the other it attaches nonspecifically to DNA. The researchers suggest that this may make it easier for the protein to get to where it's needed quickly, by attaching to the DNA strand and sliding along until it finds the specific site, then flipping into working mode.

The research was supported primarily by the National Institutes of Health and partly by the National Science Foundation.

####

For more information, please click here

Contacts:
Media Contact:
Syl Kacapyr
(607) 255-7701


Cornell Chronicle:
Bill Steele
(607) 255-7164

Copyright © Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Aculon Hires New Business Development Director December 19th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Nanomedicine

Creation of 'Rocker' protein opens way for new smart molecules in medicine, other fields December 18th, 2014

Iranian Researchers Produce Electrical Pieces Usable in Human Body December 18th, 2014

Unraveling the light of fireflies December 17th, 2014

First Home-Made Edible Herbal Nanodrug Presented to Pharmacies across Iran December 17th, 2014

Discoveries

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Iranian Scientists Use Nanotechnology to Increase Power, Energy of Supercapacitors December 18th, 2014

Announcements

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Aculon Hires New Business Development Director December 19th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE