‘Molecular motor’ twice as powerful as auto engine

December 26th, 2008 - 11:06 am ICT by IANS  

Washington, Dec 26 (IANS) A powerful “molecular motor” that packages DNA into the head segment of some viruses during their assembly delivers twice as much punch as an auto engine, according to a new study.Packaging DNA is an essential step in the ability of virus to multiply and infect new host organisms.

Parts of the motor move in sequence like the pistons in a car’s engine, progressively drawing the genetic material into the virus’s head, or capsid, said Michael Rossmann, Purdue University professor of biological sciences.

The motor is needed to insert DNA into the capsid of the T4 virus, which is called a bacteriophage because it infects bacteria. The same kind of motor, however, also is likely present in other viruses, including the human herpes virus.

Other researchers have determined that the T4 molecular motor is the strongest yet discovered in viruses and proportionately twice as powerful as an automotive engine, said a Purdue release. The study has been detailed in the online edition of the journal Cell.

The motors generate 20 times the force produced by the protein myosin, one of the two proteins responsible for the contraction and strength of muscles.

“Molecular motors in double-stranded DNA viruses have never been shown in such detail before,” said Siyang Sun, a postdoctoral research associate working in Rossmann’s lab.

“This research is allowing us to examine the inner workings of a virus packaging motor at the atomic level,” the authors said. “This particular motor is very fast and powerful.”

The virus consists of a head and tail portion. The DNA-packaging motor is located in the same place where the tail eventually connects to the head. Most of the motor falls off after the packaging step is completed, allowing the tail to attach to the capsid.

The DNA is a complete record of a virus’s properties, and the capsid protects this record from damage and ensures that the virus can reproduce by infecting a host organism.

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