University of Pittsburgh
May 7, 2001


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PITTSBURGH, May 8 -- The complex process in which hundreds of protein molecules assemble around a single DNA molecule into a virus is like an intricately choreographed ballet, say researchers at the University of Pittsburgh who announced in the April 27 issue of Science that they are the first to witness one of the main sequences of this microscopic dance in high resolution.

Roger Hendrix and Robert Duda, members of the Pittsburgh Bacteriophage Institute and the Biological Sciences Department at Pitt, are studying how viruses are assembled with colleagues from the National Institutes of Health in Bethesda, MD; the Institut de Biologie Structurale in Grenoble, France; and the Scripps Research Institute in La Jolla, CA.

The researchers studied the bacterial virus, HK97, and its precursor particle, or procapsid, using cryoelectron microscopy and X-ray crystallography, and were able for the first time to see at high resolution some of the proteins' movements.

"Coordinated like dancers in a ballet, the proteins initially assemble into a loosely organized structure, then progressively slip, slide, wiggle, and change their shapes, to produce a tightly intertwined and remarkably tough structure," said Hendrix.

Viruses have been likened to tiny spaceships that carry virus genes from the cell where they were created to the next cell the virus infects. The proteins that surround the DNA of the virus have two jobs: they must protect the DNA during transit, and they must deliver the DNA intact through the defenses of the cell in the act of infection.

"Once we understand in detail how viruses get assembled from their parts, we can start to think about how we might use that knowledge to sabotage the life cycles," said Duda.

"This should open the door for a lot of biologists," said Hendrix. "Even though we're looking at the behavior of only one particular protein of one particular bacterial virus, what we learn should be applicable to understanding lots of other proteins that carry out important reactions in the cell."