Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Border control: study shows how proteins permit entry to a cell

17.10.2008
The means by which proteins provide a 'border control' service, allowing cells to take up chemicals and substances from their surroundings, whilst keeping others out, is revealed in unprecedented molecular detail for the first time today (16 October) in Science Express.

The scientists behind the new study have visualised the structure of a protein called Microbacterium hydantoin permease, or 'Mhp1', which lives in the oily membrane that surrounds bacteria cells. It belongs to a group of proteins known as 'transporters' which help cells take up certain substances from the environment around them.

This is the first time scientists have been able to show how a transporter protein opens and closes to allow molecules across the membrane and into the cell, by accurate analysis of its molecular structure in different states.

Professor So Iwata from Imperial College London's Division of Molecular Biosciences in the Department of Life Sciences, one of the authors of the new study, explains that solving the structure of the Mhp1 bacterial transporter protein is very important because hundreds of similar transporters are found in the membranes of human cells:

"Transporter proteins play an important role in the human body - they are responsible for letting different substances, including salts, sugars and amino acids, into our cells and are targets for a large number of drugs. Understanding the details of how this transport mechanism works may help researchers to design new, more effective, drugs in the future," he said.

The group's research into this protein began in 2000 with a joint project with the Ajinomoto Company from Japan. This company work with a bacterium called Microbacterium liquefaciens which has the Mhp1 protein in its cell membranes. The project revealed that Mhp1 helps the uptake of amino acid-like molecules called hydantoins across the otherwise impermeable cell membrane.

Professor Peter Henderson from the University of Leeds, co-author of the study, said: "The major problem was to produce enough protein for the structural studies. We developed methods for the amplified expression of the Mhp1 protein in a genetically-engineered host organism, Escherichia coli, and procedures for the subsequent efficient purification of the protein from the cell membranes. We could then maintain a 'pipeline' to supply an exceptional amount of the membranes containing the excess Mhp1 protein to our colleagues at Imperial".

Professor Iwata and his colleagues analysed the structure of Mhp1 using the facilities at the Membrane Protein Laboratory (MPL), which is an Imperial College outstation at the Diamond Light Source national synchrotron facility in Oxfordshire. They used the MPL, which is a dedicated facility for membrane protein structural studies, to build an accurate picture of the Mhp1 protein binding to hydantoin.

The researchers analysed the structure of Mhp1 before and after it had taken in a hydantoin molecule from outside the cell, and also used the structure of a related transporter, vSGLT, for insight into the latter stages of the take-up process. These three structures revealed new molecular-level detail of how Mhp1 transports a hydantoin molecule across the cell membrane.

The researchers saw that the Mhp1 protein opens up on its outer-facing side, allowing the hydantoin molecule to move inside. Once the hydantoin is bound, the 'door' to the outside world closes behind it, ensuring that no other substances have been let in. Then the gate on the inward-facing side opens to release the hydantoin into the cell.

Professor Iwata comments on the significance of the discovery, saying: "Our research has revealed the detailed molecular function of an important membrane protein. We now know how the protein facilitates the movement hydantoin across the cell membrane without letting any other substances through at the same time. This mechanism is likely to be shared by many cell membrane proteins, including those in the human body, so this is an important step forward in our understanding of the fundamental processes which occur in our cells."

Professor Iwata leads an international team of scientists at the Membrane Protein Laboratory at the Diamond Light Source. The MPL is a joint venture between Imperial College London and Diamond Light Source, with funding from the Wellcome Trust and the Japan Science and Technology Agency.

Professor Henderson is Scientific Director of the EU-funded European Membrane Protein consortium, 'EMeP', which promotes collaborative research on membrane proteins between 18 European Institutions.

The Science Express research out today was carried out by researchers from Imperial College and the University of Leeds, in collaboration with scientists from Japan and Iran. The work was funded in the UK by the BBSRC, the Japan Science and Technology Agency, the EU, the Wellcome Trust and Ajinomoto Co.

Danielle Reeves | alfa
Further information:
http://www.imperial.ac.uk

Further reports about: Cell Iwata Membrane Mhp1 Microbacterium Protein cell membrane human body hydantoin revealed substances

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 >>>