The researchers suspect that this high pressure helps the virus spurt its DNA into a cell once it has latched onto the surface. Once the DNA gets inside, it begins retooling the cell to manufacture new viruses. The process eventually kills the cell, but not before generating thousands more viruses to spread the infection.

Such tight packing is achieved by one of the most powerful molecular motors ever observed, stronger than the motors that move our muscles or the nanoscale molecular motors that duplicate DNA or transcribe it into RNA. The motor the researchers studied is part of the bacteriophage 29 (phi-29), a virus that is the scourge of the common soil bacterium Bacillus subtilis.

"Pound for pound, this is stronger than any known molecular motor, and can pack DNA to a pressure of about 60 atmospheres," said biophysicist Carlos Bustamante, professor of physics and of molecular and cell biology in the College of Letters & Science at UC Berkeley. A bottle of champagne typically is under pressure of five to six atmospheres, the equivalent of nearly one hundred pounds per square inch.

"Many human viruses, such as the herpes viruses that cause herpes simplex, chicken pox and shingles, are thought to pack their DNA in the same way, so understanding how this process works could help us design better drugs to interfere with the packing part of the infection cycle of the virus, and perhaps halt infection," said Bustamante, who also is an investigator in the Howard Hughes Medical Institute at UC Berkeley and a researcher in the Physical Biosciences Division of Lawrence Berkeley National Laboratory.

Adenoviruses, popular today with gene therapists as vehicles for ferrying genes into cells, also
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Contact: Robert Sanders
rls@pa.urel.berkeley.edu
510-643-6998
University of California - Berkeley
18-Oct-2001