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NSF Press Release


Embargoed until 2:00 P.M., EST
NSF PR 02-07 - January 30, 2002

Media contact:

 Andrea M. Dietrich

 (703) 292-8070


Program contact:

 Kamal Shukla

 (703) 292-8444


New Understanding of Complex Virus Nano-Machine for Cell Puncturing and DNA Delivery

Researchers have learned how the bacterial virus, bacteriophage T4, attacks its host, the E. coli bacterium. This discovery could eventually lead to a new class of antibiotics.

Funded primarily by the National Science Foundation and published in the January 31, 2002 issue of the journal Nature, the research describes for the first time how the virus uses a needle-like, biochemical puncturing device to invade its host. "We show, in its entirety, a complex machine that allows a virus to efficiently infect its unfortunate host cell, the E. coli. The baseplate portion of the virus tail is essential in this process," says lead researcher Michael Rossmann of Purdue University. Rossmann conducted the research with colleagues Shuji Kanamaru, Petr Leiman, and Paul Chipman of Purdue University, Victor Kostyuchenko and Vadim Mesyanzhinov of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry (Russia), and Fumio Arisaka of the Tokyo Institute of Technology (Japan).

Because of increasing resistance of infectious bacteria to pharmaceutical antibiotics like penicillin, new antibiotic tools are needed. Bacteriophages may play a future role in controlling disease-causing bacteria. "Knowing the exact mechanism of T4 bacteriophage infectivity is a significant breakthrough. This information could eventually help in creating "designer viruses" that could be the next class of antibiotics," said Kamal Shukla, the NSF project officer for this research.

Although only about a hundred nanometers in length and width, bacteriophage T4 is considered the "Tyrannosaurus rex" of bacteriophages as it is one of the largest of the bacterial viruses. It is also a "tailed virus" because it has a tail with fibers that are used to grip its host. The tailed viruses are very common; up to one billion phages can exist in a milliliter of freshwater.

The T4 virus consists of a head, tail, baseplate, and tail fibers - six that are long, and six that are short. The long fibers first find the E. coli and make a loose attachment; then the short fibers fasten to get a tighter grip.

The baseplate is the "nerve center" of the virus. When the long and short fibers attach to E. coli, the baseplate transmits this message to the tail, which contracts like a muscle. The baseplate both controls the needlepoint of the tail and the cutting enzyme that make a tiny, nanometer-sized hole through the cell wall of the E. coli. The viral DNA is then squeezed through the tail into the host. The E. coli, thus infected, starts to make only new phage particles and ultimately dies. "Our research described for the first time the structure of phage baseplate proteins and their role in cutting through the host cell wall," said Rossmann.

For more information, see: http://news.uns.purdue.edu/UNS/ html4ever/020130.Rossmann.T4.html

News Video Available

Schematic of T4 Bacteriophage
"T4 bacteriophage is a virus that consists of an icosahedral (20 sided) head, contacting tail, six short and six long fibers for attaching to its E. coli victim, and a base plate that is the nerve center for communicating between the fibers and the tail."
Credit: The figure has been adapted by Petr Leiman (Purdue University) from a drawing by Fred Eiserling (UCLA).
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A reconstructed computer image generated by the SPIDER software
"A reconstructed computer image generated by the SPIDER software (created by Joachim Frank and colleagues at New York University) from 418 frozen hydrated electron images that shows the protein structure of the baseplate - tail tube assembly. The area labeled (gp27-gp5*-gp5C)3 is the needlepoint that penetrates the E. coli cell wall. The cutting enzyme activity is located around the middle of the needle. Figure a is a stereo view of the surface of the assembly and Figure b is a cross section of the assembly on an atomic scale. The 100 Angstrom scale corresponds to one millionth of a cm."
Credit: Rossmann and coworkers of Purdue University, Arisaka and coworkers of the Tokyo Institute of Technology, and Mesyanzhinov and coworkers of the Shemyakin-Ovchinnikov Institute of Moscow. Reprinted with the permission of Nature.
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