Close-up of a Viral Base-Plate Mechanism

Researchers have used a combination of electron microscopy and x-ray crystallography to assemble a high-resolution three-dimensional image of the bacteriophage T4 base-plate structure.

The base plate is a complex protein mechanism that changes its conformation from a hexagon to a star shape when the virus binds to the bacterium. A team of investigators from Purdue University (West Lafayette, IN, USA; www.purdue.edu), the Institute of Bioorganic Chemistry of the Russian Academy of Sciences (Moscow), and the Tokyo Institute of Technology (Japan) pooled their resources to develop the image of the T4 base plate that was published in the August 17, 2003, issue of Nature Structural Biology.

They described the three-dimensional structure of the base-plate-tail tube complex determined at a resolution of 12 angstroms. The base plate had a six-fold symmetric, dome-like structure, 520 angstroms in diameter and 270 angstroms long, assembled around a central hub. A 940 angstroms-long and 96 angstroms-diameter tail tube, coaxial with the hub, was connected to the top of the base plate. At the center of the dome was a needle-like structure that was previously identified as a cell-puncturing device. They also identified the locations of six proteins with known atomic structures, and established the position and shape of several other base-plate proteins.

"We now have a fairly complete picture of the base plate, the part of the virus that latches onto its cellular victim,” said senior author Dr. Michael Rossmann, professor of biologic sciences at Purdue University. "Armed with this knowledge, we should obtain a better understanding of how this virus injects its genetic material into its host. It could be the key to stopping the process or even harnessing it to benefit humanity.”





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Russian Academy of Sciences
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