Featured Research

from universities, journals, and other organizations

Long-sought Protein Structure May Help Reveal How 'Gene Switch' Works

Date:
February 9, 2009
Source:
National Institute of Standards and Technology
Summary:
The bacterium behind one of mankind's deadliest scourges, tuberculosis, is helping researchers at move closer to answering the decades-old question of what controls the switching on and off of genes that carry out all of life's functions.

Computer model of the defined structure for the cyclic AMP receptor protein (CRP) found in Mycobacterium tuberculosis. The two subunits of the protein (colored purple on the left and green on the right) are genetically identical but, surprisingly were found to be asymmetric (different in shape) for the areas shown in white (top). This is the "off" state of the CRP that is unable to activate genes necessary for the microbe's survival.
Credit: Travis Gallagher, NIST

The bacterium behind one of mankind's deadliest scourges, tuberculosis, is helping researchers at the Commerce Department's National Institute of Standards and Technology (NIST) and the Department of Energy's Brookhaven National Laboratory (BNL) move closer to answering the decades-old question of what controls the switching on and off of genes that carry out all of life's functions.

Related Articles


The NIST/BNL team reports that it has defined—for the first time—the structure of a "metabolic switch" found inside most types of bacteria—the cyclic AMP (cAMP) receptor protein, or CRP—in its "off" state. CRP is the "binding site" (attachment point) for cAMP, a small molecule that, once attached, serves as the signal to throw the switch. This "on" state of CRP then turns on the genes that help a microbe survive in a human host.

The researchers hope that once the switching mechanism is understood the data can be used to develop new methods for preventing tuberculosis and other pathogenic bacterial diseases.

"We know that many pathogenic bacteria use cAMP as a signal for activating genes that keep the microbes thriving in adverse conditions, and therefore, remaining virulent," says NIST biochemist and lead author Travis Gallagher. "Blocking these processes might provide ways to shut down infections and save lives."

Additionally, the researchers believe that learning how this specific protein switch works may provide insight into how genes in general are regulated.

The biochemical puzzle surrounding the CRP switch is the mechanism by which the protein binds cAMP at one end, then attaches to—and activates—a gene (DNA) at the other end. Believing that the protein somehow changes its overall shape after binding cAMP, researchers set out 25 years ago to study the structure of CRP in both its active state (with cAMP bound to it) and inactive state (without bound cAMP) to document where the morphing occurs.

Unfortunately, the task proved to be extremely difficult. Using CRP from the bacterium Escherichia coli, researchers were able to crystallize the protein in its active ("on") state and examine the structure using a technique called X-ray diffraction. However, the structure of the inactive ("off") E. coli CRP eluded them as attempts to crystallize it repeatedly failed. With only the structure of the "on" state defined, the genetic switching mechanism remained a mystery.

The breakthrough was achieved when Gallagher; NIST colleagues Prasad Reddy, Natasha Smith and Sook-Kyung Kim; and BNL's Howard Robinson substituted the CRP from Mycobacterium tuberculosis [the pathogen that causes tuberculosis] for the E. coli protein.

The team's initial success—obtaining crystals of CRP in the "off" state—was dramatic given that no one had accomplished the feat in nearly three decades of trying with E. coli. But the real excitement came when the crystals were examined with X-ray diffraction.

"Although the M. tuberculosis protein in the ‘off' state consists of two subunits that are genetically identical, we were surprised to see that the subunits were not structurally symmetrical as well," Gallagher says. "In most two-subunit proteins, each subunit has the same conformation as the other."

Gallagher says that the NIST/BNL team theorizes that it is the asymmetry in the absence of cAMP that prevents the protein from attaching to DNA. This, in turn, keeps CRP from activating genes when they are not needed.

"Our next step is to crystallize M. tuberculosis CRP in the active state and define its structure," Gallagher says. "When that is accomplished, we'll be able to see the identical protein from the same organism in both states, which may give us the means to explain how CRP switches from its asymmetric form [inactive state] to its symmetrical [active state] form."

The work detailed in the Journal of Biological Chemistry paper was performed at the University of Maryland Biotechnology Institute (UMBI)'s Center for Advanced Research in Biotechnology (CARB), a partnership among UMBI, NIST and Montgomery County, Md., that advances biotechnology by integrating chemical, physical and biomolecular sciences through research on biomolecular structure and function, systems biology and biometrology, and through the development of new technologies for measurement, analysis and design.

As a non-regulatory agency, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. D.T. Gallagher, N. Smith, S-K Kim, H. Robinson and P.T. Reddy. Profound asymmetry in the structure of the cAMP-free cAMP receptor protein (CRP) from Mycobacterium tuberculosis. Journal of Biological Chemistry, Online Feb 4, 2009

Cite This Page:

National Institute of Standards and Technology. "Long-sought Protein Structure May Help Reveal How 'Gene Switch' Works." ScienceDaily. ScienceDaily, 9 February 2009. <www.sciencedaily.com/releases/2009/02/090206221922.htm>.
National Institute of Standards and Technology. (2009, February 9). Long-sought Protein Structure May Help Reveal How 'Gene Switch' Works. ScienceDaily. Retrieved January 31, 2015 from www.sciencedaily.com/releases/2009/02/090206221922.htm
National Institute of Standards and Technology. "Long-sought Protein Structure May Help Reveal How 'Gene Switch' Works." ScienceDaily. www.sciencedaily.com/releases/2009/02/090206221922.htm (accessed January 31, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, January 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CDC: Get Vaccinated for Measles

CDC: Get Vaccinated for Measles

Reuters - US Online Video (Jan. 30, 2015) The CDC is urging people to get vaccinated for measles amid an outbreak that began at Disneyland and has now infected more than 90 people. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Obama To Outline New Plan For Personalized Medicine

Obama To Outline New Plan For Personalized Medicine

Newsy (Jan. 30, 2015) President Obama is expected to speak with drugmakers Friday about his Precision Medicine Initiative first introduced last week. Video provided by Newsy
Powered by NewsLook.com
NFL Concussions Down; Still on Parents' Minds

NFL Concussions Down; Still on Parents' Minds

AP (Jan. 30, 2015) The NFL announced this week that the number of game concussions dropped by a quarter over last season. Still, the dangers of the sport still weigh on players, and parents&apos; minds. (Jan. 30) Video provided by AP
Powered by NewsLook.com
U.S. Wants to Analyze DNA from 1 Million People

U.S. Wants to Analyze DNA from 1 Million People

Reuters - US Online Video (Jan. 30, 2015) The U.S. has proposed analyzing genetic information from more than 1 million American volunteers to learn how genetic variants affect health and disease. Rough Cut (no reporter narration). 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