Featured Research

from universities, journals, and other organizations

New probe technology illuminates the activation of light-sensing cells

Date:
August 18, 2010
Source:
Rockefeller University
Summary:
Ultimately, Charles Darwin's "endless forms most beautiful and most wonderful" can be boiled down to a scant 20 or so amino acids, the basic building blocks of life. From this parsimonious palette, nature paints the proteins that make up the wild diversity of life on earth, from the simplest bacteria to the most complicated structure in the known universe -- the human brain. Now, research reveals a new technique for tagging proteins with non-natural amino acids to scrutinize details about how they function.

Seeing (infra)red. Scientists designed genetically encoded probes to examine the workings of the visual pigment rhodopsin (pictured above) with infrared spectroscopy. The probes revealed that light causes changes in the protein much faster than previously believed.
Credit: Image courtesy of Rockefeller University

Ultimately, Charles Darwin's "endless forms most beautiful and most wonderful" can be boiled down to a scant 20 or so amino acids, the basic building blocks of life. From this parsimonious palette, nature paints the proteins that make up the wild diversity of life on earth, from the simplest bacteria to the most complicated structure in the known universe -- the human brain. Now, in work published online by Nature, researchers from The Rockefeller University reveal a new technique for tagging proteins with non-natural amino acids to scrutinize details about how they function.

The experiments in Nature yield new findings about rhodopsin, the light sensitive cell receptor that is crucial to dim-light vision, showing that light causes changes in the structure of the protein much faster than previously believed -- on the order of tens of microseconds rather than milliseconds. Thomas P. Sakmar, head of the Laboratory of Molecular Biology and Biochemistry, and postdoctoral associate Shixin Ye, worked with colleagues in Germany, England, Spain and Switzerland, to combine a variety of genetic engineering techniques to introduce an amino acid, azidoF, a relative of phenylalanine, into several points on rhodopsin. The three-nitrogen-atom azido is an especially good probe for three reasons: In contrast to other tags, azido does not exist naturally in mammals, which makes it easier to "see," or distinguish from other molecules in the cell; it is small enough to not interfere with a protein's normal functioning; and it has chemical properties that make it a good handle on which to hang other molecules, like fluorescent probes.

In fact, the method could in principle be applied to place a fluorescent probe at any point in any protein in a mammalian cell. "The long-term goal is to label receptors in live cells and do single molecule fluorescent studies," says Sakmar, who is Richard M. and Isabel P. Furlaud Professor. Such experiments could illuminate the minute functional differences that differentiate proteins the world over.

Similar approaches have been successfully used in bacteria, but last year, the researchers first showed that their method could be applied to mammalian cells with such specificity and efficiency, the scientists say. Extensive genetic screening allowed the team to target the azido probes efficiently. They then confirmed the presence of azido with fourier transform infrared (FTIR) difference spectroscopy, which measures stretching frequencies of the atoms in the amino acids that make up a protein.

Because azido has a unique vibration frequency that is sensitive to its surroundings, the team was able to use the spectroscopic data to confirm structural changes rhodopsin undergoes in light versus dark. "What you want is a probe that doesn't perturb the protein and one that can tell you something about its structure and function," Sakmar says. "That's what we have here."

The scientists were able to see previously unobserved changes in the structure of rhodopsin, which is a model for the ubiquitous G protein coupled receptors (GPCRs), heptahelical, transmembrane receptors found in eukaryotic cells. There are more than 700 GPCRs in the human genome alone that constitute different signaling systems, activated by light-sensitive molecules, odors, neurotransmitters, hormones and pheromones. The scientists looked at regions of the GPCR, in this case rhodopsin, which are broadly shared or conserved among related receptors.

"We have found that the activation process that begins moving the helices apart -- the earliest stage of signal transduction -- is faster than predicted, maybe an order of magnitude faster," Sakmar says. He hopes to use the technique to identify the mechanical components of the switch machinery that activate the receptors, he says, which are involved in a wide range of diseases and are the targets of many pharmaceuticals.


Story Source:

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


Journal Reference:

  1. Ye et al. Tracking G-protein-coupled receptor activation using genetically encoded infrared probes. Nature, 2010; 464 (7293): 1386 DOI: 10.1038/nature08948

Cite This Page:

Rockefeller University. "New probe technology illuminates the activation of light-sensing cells." ScienceDaily. ScienceDaily, 18 August 2010. <www.sciencedaily.com/releases/2010/04/100427115553.htm>.
Rockefeller University. (2010, August 18). New probe technology illuminates the activation of light-sensing cells. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2010/04/100427115553.htm
Rockefeller University. "New probe technology illuminates the activation of light-sensing cells." ScienceDaily. www.sciencedaily.com/releases/2010/04/100427115553.htm (accessed October 23, 2014).

Share This



More Plants & Animals News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Working Mother DIY: Pumpkin Pom-Pom

Working Mother DIY: Pumpkin Pom-Pom

Working Mother (Oct. 22, 2014) How to make a pumpkin pom-pom. Video provided by Working Mother
Powered by NewsLook.com
Goofy Dinosaur Blends Barney and Jar Jar Binks

Goofy Dinosaur Blends Barney and Jar Jar Binks

AP (Oct. 22, 2014) A collection of dinosaur bones reveal a creature that is far more weird and goofy-looking than scientists originally thought when they found just the arm bones nearly 50 years ago, according to a new report in the journal Nature. (Oct. 22) Video provided by AP
Powered by NewsLook.com
San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Raw: Bear Cub Strolls Through Oregon Drug Store

Raw: Bear Cub Strolls Through Oregon Drug Store

AP (Oct. 22, 2014) Shoppers at an Oregon drug store were surprised by a bear cub scurrying down the aisles this past weekend. (Oct. 22) Video provided by AP
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


Plants & Animals

Earth & Climate

Fossils & Ruins

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