Study reveals surprising details of the evolution of protein translation

August 12, 2008

A new study of transfer RNA, a molecule that delivers amino acids to the protein-building machinery of the cell, challenges long-held ideas about the evolutionary history of protein synthesis.

In the study, researchers report that the dual functions of transfer RNA (reading the genetic blueprint for a protein, and adding a specific amino acid to the protein as it is formed) appear to have originated independently of one another. The new findings are detailed in the July 30 Public Library of Science (PLoS) ONE.

University of Illinois crop sciences professor Gustavo Caetano-Anollés and postdoctoral researcher Feng-Jie Sun made the discovery by looking for clues to the evolution of protein translation in the sequence and structure of transfer RNA (tRNA).

"Structure is highly conserved, capturing information that is evolutionarily deep," Caetano-Anollés said. "It was only logical to focus on transfer RNA, a molecule that is believed to be very ancient and is truly central to the entire protein synthesis machinery." During protein synthesis, tRNA's dual function is reflected in its unique

L-shaped structure. One end of the molecule decodes messenger RNA (a molecule that carries instructions for the sequence of amino acids in a protein), while the other transfers a specific amino acid to the growing protein chain.

In previous studies, scientist assumed that the two functional domains of tRNA had evolved together. Sun and Caetano-Anollés put this assumption to the test.

They began by constructing an evolutionary family tree based on the sequence and two-dimensional structures of tRNA molecules representing every domain of life (bacteria; the microbes known as archaea; and eucarya, the domain that includes animals, plants, fungi and many other organisms) as well as viruses.

There are several dozen tRNAs (each reads a specific region of the genetic blueprint for a protein and each carries only one of the 20-plus amino acids found in proteins) so the researchers looked for clues to their evolutionary histories by comparing their physical and functional traits.

They converted the unique features of the individual tRNA cloverleaf structures into coded characters, a process that allowed a computerized search for the most parsimonious (the simplest, most probable) tRNA family trees for different organismal lineages. In this way they were able to test competing evolutionary hypotheses against the data mined from the structure of the tRNA itself.

"Our findings uniquely focus on structure, the actual aspect of the molecule that encases its function," Caetano-Anollés said.

The analysis indicated that the two functions of the tRNA had different evolutionary histories, Sun said, which suggests that they were acquired at different points in time.

The study predicted that the loading of amino acids on tRNA molecules preceded the refinement of the genetic code into codons, the regions on the messenger RNA that are read by individual tRNAs.

"For the first time, we believe we make this distinction between the evolution of the genetic code (codon discovery) and the evolution of amino acid charging," Sun said.

Source: University of Illinois at Urbana-Champaign

Explore further: New approach improves potential HIV vaccine

Related Stories

New approach improves potential HIV vaccine

March 29, 2017

By engineering an on/off switch into a weakened form of HIV, University of Nebraska-Lincoln researchers have enhanced the safety and effectiveness of a potential vaccine for the virus that has killed approximately 35 million ...

Novel group of giant viruses discovered

April 6, 2017

Viruses have a ubiquitous presence in the world. Their population is estimated to be 1031, 10 times greater than the nonillion (1030) of microbes on the planet—a figure that surpasses the number of stars in the Milky Way. ...

'Rhythm' of protein folding encoded in RNA, biologists find

January 31, 2013

(Phys.org)—Multiple RNA sequences can code for the same amino acid, but differences in their respective "optimality" slow or accelerate protein translation. Stanford biologists find optimal and non-optimal codons are consistently ...

Scientists crack mystery of protein's dual function

December 13, 2009

Researchers at The Scripps Research Institute have solved a 10-year-old mystery of how a single protein from an ancient family of enzymes can have two completely distinct roles in the body. In addition to providing guidance ...

Copycat protein finds a perfect match

November 19, 2010

As proteins are synthesized during messenger RNA translation, fresh amino acids are delivered to the ribosome of the cell by nucleic acid molecules known as transfer RNAs (tRNAs). Each amino acid has a cognate tRNA, and the ...

Recommended for you

Vinegar offers hope in Barrier Reef starfish battle

April 27, 2017

Coral-munching crown-of-thorns starfish can be safely killed by common household vinegar, scientists revealed Thursday in a discovery that offers hope for Australia's struggling Great Barrier Reef.

Humans in America '115,000 years earlier than thought'

April 26, 2017

High-tech dating of mastodon remains found in southern California has shattered the timeline of human migration to America, pushing the presence of hominins back to 130,000 years ago rather than just 15,000 years, researchers ...

'Iceball' planet discovered through microlensing

April 26, 2017

Scientists have discovered a new planet with the mass of Earth, orbiting its star at the same distance that we orbit our sun. The planet is likely far too cold to be habitable for life as we know it, however, because its ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.