Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers Observe Spontaneous 'Ratcheting' Of Single Ribosome Molecules

06.06.2008
Researchers report this week that they are the first to observe the dynamic, ratchet-like movements of single ribosomal molecules in the act of building proteins from genetic blueprints.

Their study, published in the journal Molecular Cell, reveals a key mechanism in the interplay of molecules that allows cells to build the proteins needed to sustain life.

Cells use a variety of tools to build proteins, beginning with messenger RNA, a ribbon-like molecule that codes for the sequence of amino acids in the protein. Another molecule, transfer RNA (tRNA) is uniquely qualified to read this code, but can do so only within the confines of the ribosome. Transfer RNAs bring individual amino acids into the ribosome where they are assembled into proteins. Various other proteins also participate in the process.

When protein translation occurs, single tRNAs enter specific sites in the ribosome, read the code and deliver their amino acids – one by one – to a growing protein chain. The ribsome transits along the messenger RNA as the protein is built, releasing the “deacylated” tRNA through an exit site.

... more about:
»EF-G »RNA »acid »amino »amino acids »ribosomal »spontaneously »tRNA

A ribosome is made up of two subunits composed of ribonucleic acids (RNAs) and about 50 individual proteins.

The ribosome was once considered a static “workbench” for the assembly of new proteins. A recent study by researchers at the Wadsworth Center in Albany, N.Y., using cryo-electron microscopy, showed the ribosomal subunits in two distinct positions relative to one another, however. They proposed that the motion of the subunits depended on a protein catalyst, elongation factor G (EF-G).

In the new study, a team led by University of Illinois physics professor Taekjip Ha used fluorescence resonance energy transfer (FRET) to observe in real time the movement of the ribosomal subunits that is essential for protein synthesis. The team collaborated with Harry Noller, of the University of California at Santa Cruz, who provided expertise on the ribosome.

FRET makes use of fluorescent molecules whose signals vary in intensity depending on their proximity to one another. By labeling each of the two subunits of a single ribosomal molecule with these fluorescent markers, the researchers were able to watch the subunits move in relation to one another.

When Ha and postdoctoral fellow Peter Cornish observed the signal from the labeled ribosomes, they saw a spontaneous back-and-forth rotation between the subunits – even in the absence of the elongation factor, EF-G.

“Other researchers proposed that this rotation is induced by EF-G – that you have to have EF-G to cause this rotation,” Ha said. “But we showed that no, that’s not the case. Actually the ribosome can rock back and forth spontaneously, and can do it quite rapidly.”

The researchers were able to view this motion even in the absence of tRNA. The ribosomal subunits were spontaneously switching back and forth between the classical (that is, non-rotated) state and a hybrid (rotated) state.

When they added a single tRNA with an amino acid permanently attached to it, the ribosome became “essentially stuck in the classical, non-rotated state,” Cornish said. “And as soon as we removed that, it started to move spontaneously.”

To better understand the role of EF-G, the researchers added a modified EF-G molecule that could not deliver its normal energy payload to the ribosome. The modified EF-G bound to the ribosome only in the rotated, hybrid state.
These findings led the researchers to propose that EF-G has a critical role in the process of protein translation: It stabilizes the rotated position of the ribosomal subunits relative to one another.

This allows the tRNA molecules to add amino acids to the growing protein and to exit, making room for the next tRNA specified in the messenger RNA code.

The researchers believe that EF-G acts as a linchpin, temporarily holding the ribosome in its rotated position until the deacylated tRNAs reposition themselves in the molecule as they move toward the exit. Once the tRNAs have accomplished this, the EF-G goes away, the ribosome ratchets back into its non-rotated position and the process begins again.

The researchers propose that this ratcheting motion allows the ribosome to advance along the messenger RNA as protein translation progresses. Without EF-G, the ribosomal subunits move in relation to one another, but are unable to progress along the messenger RNA as a protein is built.

“Many people would argue that the ribosome is one of the most important machines in our cells,” Ha said. “What’s really amazing is that it is such a massive complex that is still able to move spontaneously, to rock back and forth at a fairly rapid rate. And that movement is not just some random movement, but it’s the most important movement of the ribosome for its locomotion.”

Future studies will use FRET by labeling both the ribosomal subunits and the messenger RNA to see if the movement of the subunits and the ribosome’s transit along the messenger RNA are synchronized, Ha said.

The study was supported in part by the National Science Foundation and the National Institute of General Medical Sciences at the National Institutes of Health. Ha is an investigator with the Howard Hughes Medical Institute.

Diana Yates | University of Illinois
Further information:
http://www.uiuc.edu

Further reports about: EF-G RNA acid amino amino acids ribosomal spontaneously tRNA

More articles from Life Sciences:

nachricht Researchers find new mutation in the leptin gene
24.06.2019 | Texas Biomedical Research Institute

nachricht Straight to the heart
24.06.2019 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fraunhofer IDMT demonstrates its method for acoustic quality inspection at »Sensor+Test 2019« in Nürnberg

From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.

Reducing machine downtime, manufacturing defects, and excessive scrap

Im Focus: Successfully Tested in Praxis: Bidirectional Sensor Technology Optimizes Laser Material Deposition

The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.

Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

'Sneezing' plants contribute to disease proliferation

24.06.2019 | Agricultural and Forestry Science

Researchers find new mutation in the leptin gene

24.06.2019 | Life Sciences

Non-invasive view into the heart

24.06.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>