Featured Research

from universities, journals, and other organizations

Cracking The Genomic Code: Gene Decoding Revealed At Atomic Level

Date:
December 6, 2004
Source:
North Carolina State University
Summary:
A recent finding by a North Carolina State University biochemist advances the fundamental biology of how genetic information, encoded in DNA, is decoded for the production of proteins.

The critical decoding structure produced when modified nucleosides enable tRNA to decode by wobble recognition. Only the decoding region of a 50,000+ atom structure of the ribosome (small subunit) is shown. The modified nucleoside platform (orange) that stabilizes the codon-anticodon interaction, and the modified nucleoside that wobbles (green) are shown. The structure was determined at the atomic resolution of -3 angstroms (3 X 10 –10 meters).
Credit: Image courtesy of North Carolina State University

A recent finding by a North Carolina State University biochemist advances the fundamental biology of how genetic information, encoded in DNA, is decoded for the production of proteins.

Dr. Paul F. Agris, professor of biochemistry at NC State, and academic colleagues from England and Poland show concrete evidence in favor of the 1966 “Wobble Hypothesis” offered by Francis Crick, the co-founder of the DNA molecule and its double-helix structure, and Agris’ own “Modified Wobble Hypothesis” posed in 1991.

The scientists used x-ray crystallography of the cell’s protein-manufacturing unit, the ribosome, to provide a visual snapshot of the decoding process.

The research is published in the December 2004 edition of Nature Structural and Molecular Biology.

The Wobble Hypothesis was Crick’s attempt to make sense of how the cell decodes the genetic information of DNA – the molecule that constitutes all the genetic information in a cell – and then, from that information, makes biologically active proteins, Agris said.

DNA has 61 three-letter codes that are translated by transfer RNA (tRNA) into amino acids; proteins are made of amino acids. But there are only 20 natural amino acids. Squaring the disparity between the number of codes and the number of amino acids – there are three times as many codes as there are amino acids – became a hurdle for Crick and other early geneticists, Agris explained.

Crick attempted to clear this hurdle with the Wobble Hypothesis. He based this theory on the first report of a tRNA molecule’s chemical structure discovered by Robert Holley in 1963.

Normally, RNA molecules are composed of four nucleosides: adenosine, guanosine, cytosine and uridine (A,G,C,U). But the tRNA molecule Holley studied included a modified nucleoside called inosine (I), Agris says. Seeing this inosine in an important area of the tRNA molecule – an area that read the three-letter DNA codes when the cell synthesizes proteins – led Crick to believe that a single tRNA used inosine to read more than one code, and that therefore the 61 codes were decoded by fewer than 61 tRNAs.

As an example, Agris used the amino acid alanine, which has four codes. Crick’s hypothesis would allow that only two tRNA molecules could be capable to decode all four alanine codes. Using the modified nucleoside I in place of A, G, C or U, one tRNA may be able to read three codes, effectively “wobbling” the reading.

Twenty-five years after the Wobble Hypothesis, Agris proposed his Modified Wobble Hypothesis. It stated that modified nucleosides other than inosine would in some cases expand tRNAs ability to translate codes by wobbling to greater numbers of three-letter codes, whereas other modified nucleosides would restrict wobble to only one or two codes.

Now, in the recent paper, Agris and colleagues prove Agris’ alteration to Crick’s hypothesis was correct: Cellular modification of tRNA alters chemistry and structure in a manner critical for tRNA to decode more than one three-letter code.

Using atomic-level resolution – in which researchers can distinguish atom from atom – and working with a tRNA specific for the amino acid lysine, Agris and his colleagues show modified nucleosides enabling tRNA to decode genomic information on the ribosome, the cell’s protein synthesis machinery.

Specifically, it shows modifications enabling the decoding of two codes. One modification acts like a platform on which decoding takes place, and the other allows a novel chemical and physical interaction to occur between tRNA and the code, Agris said.

“This is the first visualization that modifications are critical for decoding the genome through wobble,” he said.

Agris says that 15 to 20 percent of tRNAs in all organisms require modified chemistries in order for codes to be properly read and protein synthesis to be successful.

“An understanding of how modified nucleosides enable and improve wobble recognition of the three-letter codes for protein synthesis opens the possibility of using modified nucleosides to expand the cells’ use of tRNA to make new proteins, or in new ways to target the protein synthesis machinery in pathogens,” Agris said.


Story Source:

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


Cite This Page:

North Carolina State University. "Cracking The Genomic Code: Gene Decoding Revealed At Atomic Level." ScienceDaily. ScienceDaily, 6 December 2004. <www.sciencedaily.com/releases/2004/12/041203095142.htm>.
North Carolina State University. (2004, December 6). Cracking The Genomic Code: Gene Decoding Revealed At Atomic Level. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2004/12/041203095142.htm
North Carolina State University. "Cracking The Genomic Code: Gene Decoding Revealed At Atomic Level." ScienceDaily. www.sciencedaily.com/releases/2004/12/041203095142.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
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:
from the past week

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