Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Catching A Sneak

14.04.2005


Weizmann Institute Scientists Reveal the Shape of a Protein That Helps Retroviruses Break into Cells



Retroviruses are among the trickier and more malicious disease agents, causing AIDS and cancers such as leukemia. The viruses manage to sneak into cells with the help of special protein assemblies scattered all over their surfaces. These retrovirus surface proteins cause the membrane envelope of the virus to fuse with the membrane of the cell, spilling virus RNA into the cell to wreak damage. Now, a team of scientists at the Weizmann Institute of Science and the Max Planck Institute for Biochemistry has obtained a close-up 3-D portrait of the large protein complex on the virus that enables its entry into the cell. Their work appeared in the Proceedings of the National Academy of Sciences, USA in March.

These protein complexes recognize and bind to specific sites on the cellular membrane and mediate the fusion process, the first steps in virus infection. However, the shape of this complex on retroviruses and the way that it works had long evaded efforts at detection by various scientific groups. The difficulty is that crystallization, the leading method of preparing proteins for structure solving, does not work well with the elaborate, envelope-bound complexes, which tend to fall apart when they are removed from the virus membrane. Dr. Deborah Fass of the Weizmann Institute’s Structural Biology Department had managed to determine the structures of assorted parts of the complex in the past, but needed a better understanding of how the complex works as a whole.


To accomplish her goal, Fass and student Nathan Zauberman teamed up with scientists from Max Planck’s Molecular Structural Biology Department in Martinsried, Germany to try an alternative method of getting an image of the complex. They turned to the electron microscope, a standard tool for observing larger structures such as cell sections.

Viewing a single, relatively small protein complex was pushing the limits of this technology, but the Max Planck group, expert at developing both the hardware and the software required for visualizing biological structures using electron microscopy, was up to the task. The technique used, known as cryo-electron tomography, involved quick-freezing the viruses in liquid ethane, capturing snapshots of them at various angles and then combining the snapshots to create three-dimensional pictures. From dozens of these digitized 3-D pictures of whole viruses, hundreds of protruding surface protein complexes could be cut out, aligned, and averaged. Though the resulting image did not have quite as high a resolution as those obtained through crystallography, it allowed the scientists to get a complete and fairly detailed picture of this important protein complex in its natural environment. “After years of trying to imagine how the pieces fit together, suddenly we had the real structure right in front of us. Some aspects of it looked familiar, but others were completely unanticipated,” says Fass.

The scientists were surprised to note that the shape of the complexes on the retroviruses bore little resemblance to other known viral envelope protein structures such as those on flu viruses. They also saw strong evidence that the protein complex undergoes a radical change in shape and arrangement of its component parts as it attaches to cells and initiates membrane fusion. Fass was able to see how a smaller protein piece she had previously isolated and analyzed by crystallization fit into the whole, giving her further clues as to how the virus locks onto the cell membrane.

The retrovirus used by Fass and the team is similar to that which causes leukemia in humans. They hope, with further research, to understand the conformational changes the envelope protein complex undergoes as it works, and to find ways to stop those changes from taking place.

Dr. Debora Fass’ research is supported by the Clore Center for Biological Physics; the Helen and Milton A. Kimmelman Center for Biomolecular Structure and Assembly; and the Leukemia Research Foundation.

Dr. Fass is the incumbent of The Lillian & George Lyttle Career Development Chair.

The Weizmann Institute of Science in Rehovot, Israel, is one of the world’s top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,500 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Alex Smith | EurekAlert!
Further information:
http://www.weizmann.ac.il

More articles from Life Sciences:

nachricht New type of photosynthesis discovered
17.06.2018 | Imperial College London

nachricht New ID pictures of conducting polymers discover a surprise ABBA fan
17.06.2018 | University of Warwick

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

A sprinkle of platinum nanoparticles onto graphene makes brain probes more sensitive

15.06.2018 | Materials Sciences

100 % Organic Farming in Bhutan – a Realistic Target?

15.06.2018 | Ecology, The Environment and Conservation

Perovskite-silicon solar cell research collaboration hits 25.2% efficiency

15.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>