Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Visualise Cellular Handmaiden That Restores Shape To Proteins

17.08.2004


A gigantic protein complex responsible for looking after bent out of shape proteins has been visualised by scientists working in Japan and the UK.



The structure of the chaperonin complex of the bacteria Thermus thermophilus reveals clues about how the important molecule may do its job of folding new or damaged proteins within cells. Led by Professor So Iwata of Imperial College London, the team of scientists announce their findings in this month’s edition of the journal Structure (August 2004).

The complex comprises three separate parts - two identical ’cage’ units lashed back to back, and a ’cap’ unit that sits atop the cage, acting as a stopper. The cage contains the unwound, or denatured, protein, while the chaperonin goes about refolding its shape using the cellular energy source, ATP.


The structure of the chaperonin complex is one of the largest and most difficult solved by scientists. Each unit of the cage or cap is made up of seven separate polypeptide chains. "It’s huge," said Professor Iwata. "The cavity can accommodate even very large proteins inside. It makes the perfect environment for the protein to fold."

It is the second structure of a chaperonin complex to be reported by scientists, and is visualised at a resolution of 2.8 Angstroms. The first was published in 1997 by the group of the late Professor Paul Sigler at Yale University, USA.

Unlike the first structure, taken from the chaperonin of gut bacterium Escherichia coli, the Thermus thermophilus structure is a more natural structure revealing the irregular oval interior of the cage’s subunits.

Thermus thermophilus is a highly thermophilic bacteria, first found living in deep-sea hot vents. It contains proteins thought to be very similar to those found in the energy powerhouses of plant and animal cells, the mitochondria.

Immediately, the largest users of this new knowledge are biochemists working on the protein and bioinformaticians, searching for similar molecules in other species. Human mitochondria likely use the same type of chaperonin to fold proteins says Professor Iwata. In time their structure may be used in the development of new drugs.

The team believe their structure leads them to an explanation of how the molecule works.

Properly folded proteins tuck away the elements that don’t mingle well with water - a property known as hydrophobicity - inside their structure. Denatured proteins with their mis-organised shape allow normally hidden elements to display on the outside, making them appear hydrophobic.

The chaperonin cap recognises the hydrophobicity and ’kicks’ the out of shape protein in to the cage for some protein folding therapy. The folding changes in the cavity are driven by the cell’s energy source, ATP. It takes just 10 seconds for a protein to properly fold in the cavity.

The scientists’ next goal is to capture these cellular handmaidens in the act of folding strings of denatured protein back together again. They already have clues as to the sorts of proteins that might be fixed by the chaperonin complex - during their work to crystallise the protein structure they identified 28 separate proteins inside the cage. "We’d like to be the first to really know what happens, when the protein is enclosed and caught in the act," says Professor Iwata.

In molecular units known as Daltons, the structure of the native chaperonin complex weighs 700 kiloDaltons. It is so big that details of its full structure had to be deposited in two parts to the freely available structure database, Protein Data Bank. It has more than six digits of atomic coordinates, or over a million atoms in the structure mapped and plotted in 3D space.

Professor Iwata is well known for solving the structure of proteins embedded in the membrane of cells, such as the crucial photosynthesis enzyme Photosystem II, published last year in Science. The crystals of chaperonin complex were grown and prepared in Iwata’s lab, and after X-ray analysis at the European synchrotron facility, all authors collaboratively solved the structure.

This work was funded by BBSRC and ATP System Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency.

Tom Miller | alfa
Further information:
http://www.imperial.ac.uk
http://www.structure.org

More articles from Life Sciences:

nachricht Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University

nachricht Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>