Featured Research

from universities, journals, and other organizations

Insight into the origin of the genetic code

Date:
August 26, 2013
Source:
University of Illinois at Urbana-Champaign
Summary:
An analysis of enzymes that load amino acids onto transfer RNAs -- an operation at the heart of protein translation -- offers new insights into the evolutionary origins of the modern genetic code, researchers report.

An analysis of enzymes that load amino acids onto transfer RNAs -- an operation at the heart of protein translation -- offers new insights into the evolutionary origins of the modern genetic code, researchers report.

Their findings appear in the journal PLOS ONE.

The researchers focused on aminoacyl tRNA synthetases, enzymes that "read" the genetic information embedded in transfer RNA molecules and attach the appropriate amino acids to those tRNAs. Once a tRNA is charged with its amino acid, it carries it to the ribosome, a cellular "workbench" on which proteins are assembled, one amino acid at a time.

Synthetases charge the amino acids with high-energy chemical bonds that speed the later formation of new peptide (protein) bonds. Synthetases also have powerful editing capabilities; if the wrong amino acid is added to a tRNA, the enzyme quickly dissolves the bond.

"Synthetases are key interpreters and arbitrators of how nucleic-acid information translates into amino-acid information," said Gustavo Caetano-Anollés, a University of Illinois professor of crop sciences and of bioinformatics. Caetano-Anollés, who led the research, also is a professor in the U. of I. Institute for Genomic Biology. "Their editing capabilities are about 100-fold more rigorous than the proofreading and recognition that occurs in the ribosome. Consequently, synthetases are responsible for establishing the rules of the genetic code."

The researchers used an approach developed in the Caetano-Anollés lab to determine the relative ages of different protein regions, called domains. Protein domains are the gears, springs and motors that work together to keep the protein machinery running.

Caetano-Anollés and his colleagues have spent years elucidating the evolution of protein and RNA domains, determining their relative ages by analyzing their utilization in organisms from every branch of the tree of life. The researchers make a simple assumption: Domains that appear in only a few organisms or groups of organisms are likely younger than domains that are more widely employed. The most universally utilized domains -- those that appear in organisms from every branch of the tree of life -- are likely the most ancient.

The researchers used their census of protein domains to establish the relative ages of the domains that make up the synthetases. They found that those domains that load amino acids onto the tRNAs (and edit them when mistakes are made) are more ancient than the domains that recognize the region on the tRNA, called an anticodon, that tells the synthetase which amino acid that tRNA should carry.

"Remarkably, we also found that the most ancient domains of the synthetases were structurally analogous to modern enzymes that are involved in non-ribosomal protein synthesis, and to other enzymes that are capable of making dipeptides," Caetano-Anollés said.

The researchers hypothesize that ancient protein synthesis involved enzymes that looked a lot like today's synthetases, perhaps working in conjunction with ancient tRNAs.

Researchers have known for decades that rudimentary protein synthesis can occur without the involvement of the ribosome, Caetano-Anollés said. But few if any have looked to the enzymes that catalyze these reactions for evidence of the evolutionary origins of protein synthesis.

Alerted to the potential importance of dipeptide formation in early protein synthesis, the researchers next looked for patterns of frequently used dipeptides in the sequences of modern proteins. They focused only on proteins for which scientists have collected the most complete and accurate structural information.

"The analysis revealed an astonishing fact," Caetano-Anollés said. "The most ancient protein domains were enriched in dipeptides with amino acids encoded by the most ancient synthetases. And these ancient dipeptides were present in rigid regions of the proteins."

The domains that appeared after the emergence of the genetic code (which Caetano-Anollés ties to the emergence of the tRNA anticodon) "were enriched in dipeptides that were present in highly flexible regions," he said.

Thus, genetics is associated with protein flexibility, he said.

"Our study offers an explanation for why there is a genetic code," Caetano-Anollés said. Genetics allowed proteins "to become flexible, thereby gaining a world of new molecular functions."


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gustavo Caetano-Anollés, Minglei Wang, Derek Caetano-Anollés. Structural Phylogenomics Retrodicts the Origin of the Genetic Code and Uncovers the Evolutionary Impact of Protein Flexibility. PLoS ONE, 2013; 8 (8): e72225 DOI: 10.1371/journal.pone.0072225

Cite This Page:

University of Illinois at Urbana-Champaign. "Insight into the origin of the genetic code." ScienceDaily. ScienceDaily, 26 August 2013. <www.sciencedaily.com/releases/2013/08/130826123136.htm>.
University of Illinois at Urbana-Champaign. (2013, August 26). Insight into the origin of the genetic code. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2013/08/130826123136.htm
University of Illinois at Urbana-Champaign. "Insight into the origin of the genetic code." ScienceDaily. www.sciencedaily.com/releases/2013/08/130826123136.htm (accessed July 30, 2014).

Share This




More Plants & Animals News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) — Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) — Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) — At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Raw: Otters Enjoy Water Slides at Japan Zoo

Raw: Otters Enjoy Water Slides at Japan Zoo

AP (July 30, 2014) — River otters were hitting the water slides to beat the summer heatwave on Wednesday at Ichikawa City's Zoological and Botanical Garden. (July 30) 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:
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