WEST LAFAYETTE, Ind. -- A study of two large virus structures shows that nature may use an "assembly-line" approach to build grand structures on a tiny scale.
Scientists at Purdue University have solved the structures of two large icosahedral viruses, providing scientists with the first three-dimensional views of viruses of this size and new insights on how viruses are assembled.
The study, published in the February issue of the journal Nature Structural Biology, reveals that the viruses' shells are made of large building blocks pieced together from protein molecules joined primarily in clusters of three.
"It appears that these viruses don't come together all at once but are assembled in pieces, like an automobile, with small subunits coming together to form larger components of the structure," says Timothy S. Baker, professor of biological sciences at Purdue and principal investigator on the study.
The use of small three-sided clusters to make larger structures may be a common tactic used by large viruses to develop stable and highly symmetrical structures, Baker says, noting that many virus shells are made from a combination of five- and six-sided clusters.
Knowing the structure of these large viruses may provide insights on how other large viruses are assembled, and may someday help scientists find ways to design antiviral agents, he says.
The viruses -- Chilo iridescent virus, a virus that infects the rice stem borer insect, and Paramecium bursaria chlorella virus type 1, a virus that infects certain freshwater algae -- are among the largest known viruses. They are about 200 times more massive than the common cold virus.
"These viruses contain well over 5,000 protein subunits," Baker says. "To form a structure of that size, so perfectly and with such symmetry, raises some mind-boggling questions about how something so precise can form from all of these individual molecules."
The process also raises some compl
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Contact: Susan Gaidos
sgaidos@uns.purdue.edu
765-494-2081
Purdue University
27-Feb-2000