Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cholera protein structure – a target for vaccines & antibiotics – described by TSRI scientists

23.05.2003


A group of researchers from The Scripps Research Institute (TSRI) has solved structures of a bacterial protein called pilin, which is required for infection by pathogens that cause human diseases like meningitis, gonorrhea, diarrheal diseases, pneumonia, and cholera.

In the latest issue of the journal Molecular Cell, the TSRI group reports two key structures of these pilins and discoveries about their assembly into fibrous "pili." Because a whole class of bacterial pathogens require the assembly of pilin into the hair-like pilus filaments on their surface in order for them to move around, attach to, and infect host cells, the authors believe that this research provides essential knowledge to help scientists develop novel antibiotics and vaccines against these deadly and emerging bacterial diseases.

This work directly focuses on two such pathogens--Pseudomonas aeruginosa, which causes severe lung infections in cystic fibrosis patients, AIDS patients, and other immunocompromised individuals, and Vibrio cholerae, which causes cholera, a potentially fatal diarrheal disease that primarily afflicts people in developing countries.



"Cholera," says TSRI Professor John Tainer, Ph.D., "is a disease that could use better vaccines."

Tainer, who is an investigator in TSRI’s Department of Molecular Biology and a member of The Skaggs Institute for Chemical Biology at TSRI, determined the atomic structure of the pilus filaments with TSRI Senior Research Associate Lisa Craig, Ph.D., and three other key researchers--TSRI Professor Mark Yeager, computational expert and director of graphics development at TSRI Michael Pique, and Dartmouth Medical School Professor Ronald Taylor.

"If we can understand their atomic structure, we can go after developing vaccines that are highly specific," says Craig, who is first author on the paper.

The Structure and How It Was Solved

The pili are used by several types of bacteria to crawl around and stick to the intestine, lung, and other mucosal surfaces, and to pick up foreign genes and DNA, bringing them aboard to potentially increase the bacteria’s pathogenicity. In cholera, these pili are essential for the infection because they allow the bacteria to clump together and form a colony that protects them from the human immune response. This makes pili a good target for vaccine design, since blocking them should block the bacterium’s ability to cause infection.

However, solving the structure of these proteins has not been easy because of their size and shape. The pili themselves are assembled from thousands of copies of a single pilin subunit protein stacked together to resemble a microscopic thread--they are several hundred times longer than they are wide.

These structures are too large and flexible to be solved with the traditional techniques of structural biology used to study small proteins. So in the current study, the TSRI team was creative and combined more than one approach.

The group first solved the structure of the individual pilin proteins from the V. cholerae bacterium using x-ray crystallography--a technique where scientists first make crystals of molecules like proteins or DNA and then expose them to x-rays. The pattern of diffracted x-rays can then be collected and analyzed to determine the structure of the molecules in the crystal. Although a fragment of the V. cholerae pilin protein was missing in their structure, they were able to infer this structure by solving a full length structure of a pilin subunit from P. aeruginosa, which is important in infections of children with cystic fibrosis.

Craig, Yeager and Tainer then used a technique called electron microscopy to understand how the pilin proteins were organized in the pilus filaments. Electron microscopy uses a beam of electrons to magnify protein assemblies and other tiny structures up to one hundred thousand times onto a digital camera or a photographic plate.

The integration of x-ray crystallography and electron microscopy allowed Craig, Pique, and Tainer to build a model of the pili otherwise impossible at that level of molecular detail. The structures gave new insights into how the pili assemble and how they contribute to the pathogenesis of the bacteria--as well as providing a unique molecular map of these proteins that should aid in the design of new vaccines and therapeutics.

The research article, "Type IV Pilin Structure and Assembly: X-ray and EM Analyses of Vibrio cholerae Toxin Coregulated Pilus and Pseudomonas aeruginosa PAK Pilin" is authored by Lisa Craig, Ronald Taylor, Michael Pique, Brian Adair, Andrew Arvai, Mona Singh, Jane Lloyd, David Shin, Elizabeth Getzoff, Mark Yeager, Katrina Forest, and John Tainer and appears in the May 23, 2003 issue of the journal Molecular Cell.

The research was funded by the National Institutes of Health, The Skaggs Institute for Research, and the Canadian Institutes of Health Research.

More on Cholera: A Deadly Disease of Developing Nations

Although cholera was once common in this country, modern water treatment has virtually eliminated the disease domestically, though it is still a concern for U.S. world travelers. In the developing world and in areas with poor sewage treatment, cholera is still a major public health problem, and these areas frequently support outbreaks of disease. Cholera can be a deadly problem for children in third world countries. Epidemic outbreaks in the past have involved changes to the pilin protein, now structurally characterized by Scripps researchers.

Cholera is caused by an acute intestinal infection with the bacterium Vibrio cholerae. This usually occurs after someone has eaten food or drank water contaminated with the pathogen.

Cholera infections are sometimes mild, but result in watery diarrhea, vomiting, and severe fluid loss about five percent of the time. These cases are life-threatening and deadly where treatment through simple rehydration with a sugar and salt mixture is not available.

There is currently no effective vaccine available for this disease. According to the Centers for Disease Control and Prevention, the only cholera vaccine licensed in the United States has been discontinued because it offers only brief and incomplete immunity. For more information, please see:

Jason Bardi | EurekAlert!
Further information:
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_g.htm.
http://www.scripps.edu/

More articles from Life Sciences:

nachricht In living color: Brightly-colored bacteria could be used to 'grow' paints and coatings
20.02.2018 | University of Cambridge

nachricht Computers aid discovery of new, inexpensive material to make LEDs with high color quality
20.02.2018 | University of California - San Diego

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Rare find from the deep sea

20.02.2018 | Life Sciences

In living color: Brightly-colored bacteria could be used to 'grow' paints and coatings

20.02.2018 | Life Sciences

Observing and controlling ultrafast processes with attosecond resolution

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>