WEST LAFAYETTE, Ind. -- Researchers at Purdue University and The Catholic University of America have discovered the structure of an enzyme essential for the operation of "molecular motors" that package DNA into the head segment of some viruses during their assembly.

The enzyme, called an ATPase, provides energy to run the motor needed to insert DNA into the capsid, or head, 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.

"This is the first time a structure has been determined of an ATPase involved in a DNA packaging motor," said Michael Rossmann, the Hanley Distinguished Professor of Biological Sciences in Purdue's College of Science.

The article's lead author is Siyang Sun (pronounced See-Young Sun), a postdoctoral research associate working in Rossmann's lab. The researchers have proposed a mechanism for how the motor works.

Findings are detailed in a paper published Thursday (March 22) in the journal Molecular Cell. The paper was written by Sun; Kiran Kondabagil, a postdoctoral research associate at The Catholic University of America; Petra Gentz, a former visiting doctoral student at Purdue; Rossmann; and Venigalla B. Rao, a professor of biology at The Catholic University of America.

"The virus first assembles the protein shell of the head and then packages the DNA into this empty capsid," Rossmann said. "This process could be likened to building a house and then filling it with furniture."

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

"This research represents a significant step forward to understanding how DNA genetic material is packaged in viruses," Rao said.

Energy to run the packaging motor is produced when the ATPa
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Contact: Emil Venere
venere@purdue.edu
765-494-4709
Purdue University
22-Mar-2007