Researchers observe single protein dimers wavering between two symmetrically opposed ...( LA JOLLA CA June 19 2009Researchers ...)

LA JOLLA, CA, June 19, 2009Researchers at The Scripps Research Institute, the University of California, San Diego, and Ohio State University have used a very sensitive fluorescence technique to find that a bacterial protein thought to exist in one "natural" three-dimensional structure (shape), can actually twist itself into a second form, depending on the protein's chemical environment. One folded form is active and the other is inactive, but the protein can easily morph from one state to another.

The scientists say their discovery, published in the online Early Edition of in The Proceedings of the National Academy of Sciences (PNAS) on June 8, 2009, emphasizes that such shape shifting by proteins is a common way of regulating cellular activities. This direct view provides a neat example of the dynamic and complex nature of proteins, contrasting with a single preferred folded structure that is determined by the energy balance between the amino acids that make them up.

The group of Scripps Research Associate Professor Ashok Deniz has conducted a series of studies that use novel fluorescence methods to show that both simple and complex proteins can swiftly change their structures. In March, Deniz and his Scripps Research team published a study, also in PNAS, demonstrating how a simple protein associated with development of Parkinson's disease can switch shapes back and forth between different structures, depending on its binding to molecular partners.

Now, a collaboration among the Deniz laboratory, the group of Jos N. Onuchic of the University of California, San Diego, (UCSD) and the laboratory of Thomas J. Magliery of Ohio State University, has shown that a protein dimer made up of two identical parts can actually twist itself so that one copy of the protein is turned upside down if its environment is only slightly altered.

"It has long been a puzzle as to how proteins, which can theoretically adopt an ex
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