Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First structure of transporter enzyme family is solved

01.08.2003


Finding will aid drug design to combat depression, stroke and diabetes. Scientists are a step closer to understanding how essential nutrients, vitamins and minerals are ferried into cells.



For the first time, a member of the Major Facilitator Superfamily (MFS) of transport proteins, found in almost every form of life, has been visualised by researchers from Imperial College London and the University of California, Los Angeles.

Reporting in Science today, the researchers reveal the structure of lactose permease, the enzyme in Esherichia coli that helps pump lactose, the major sugar in milk, into cells. Using the structure data, the researchers propose a possible mechanism of action, which is likely to be common among other transport proteins in this family.


Professor So Iwata of Imperial’s Centre for Structural Biology and senior author of the paper explains: "Membrane transport proteins play major roles in depression, stroke and diabetes. Unravelling their structure is critical not only for understanding how we function, but also to improve drug design. Indeed, two of the most widely prescribed drugs in the world, Prozac and Prilosec, act through these proteins.

"The three-dimensional structure of lactose permease gives us our first real picture of how the family of enzymes work. For example, in humans the MFS transporter GLUT4 is responsible for increased glucose uptake in response to insulin stimulation, which has important implications for diabetes. Using the structure of lactose permease we can model GLUT4 and design drugs to control glucose uptake."

Membrane transport proteins play a crucial role in maintaining the selective internal environment of cells. They act as gatekeepers by controlling the entry of nutrients and the exit of waste products. But only four transport protein structures are presently known, compared with over 30,000 soluble protein structures, because they are notoriously difficult to crystallise.

Professor Iwata’s Laboratory of Membrane Protein Crystallography is one of a small number around the world that focuses on determining the three-dimensional structure of membrane embedded proteins.

By combining expertise with Professor Ron Kaback of the University of California, who has been working on lactose permease for 30 years, they have finally solved the structure of this important protein.

Previous biochemical studies had identified six sites within the genetic code of lactose permease that are thought to be crucial to transportation. Using the latest X-ray crystallography techniques, the researchers were able to visualise how lactose permease binds to sugar.

"We have been able to pinpoint areas in the genetic code critical for binding and transport of sugar, which are consistent with information derived from biochemical studies, "said Professor Iwata.

By combining the structural data with previous findings the researchers propose a mechanism of enzyme action.

"Computer simulations show that the enzyme works in a surprisingly simple way. The enzyme is literally gate-keeping. Usually the gate is open towards the outside of the cells and various substances can reach the sugar-binding pocket in the middle of the enzyme, embedded in the cell membrane.

"Only when the enzyme identifies lactose does the other gate, connected to the inside of the cell, open and let the sugar go through. This process is driven by energy called the ’proton motive force’ and should be common among membrane transport proteins."

Professor Iwata added: "Only 40 years ago the idea that genes could be specifically turned on or off in response to different environmental conditions was revolutionary. It was studies in E. coli that showed the bacterial cellular machinery needed to digest lactose is only activated when glucose is not available. Now we have a detailed molecular understanding of how lactose permease contributes to this process."

Judith H Moore | EurekAlert!
Further information:
http://www.imperial.ac.uk

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>