"We hope our RNA mimics of GFP open up the road to discovery," he says.
The RNAs developed by the Jaffrey group function like GFP, a natural protein expressed in jellyfish that exhibits a green fluorescence. GFP has enabled scientists to watch how proteins move in cells, providing powerful new insights into their roles in cell function. The DNA that encodes GFP is placed next to a gene that encodes for a protein, resulting in the expression of a protein fused to GFP, which can be observed by specialized forms of microscopy.
To make an RNA that functions like GFP, the Weill Cornell investigators took advantage of the ability of RNA to fold into complex three-dimensional shapes. Their goal was to create two new entities: a synthetic RNA sequence that would adopt a specific shape, and a small molecule that would bind to the new RNA and begin to fluoresce. "These were two huge challenges," says Dr. Jaffrey. "One challenge was to come up with an RNA sequence that could 'switch on' a small molecule. The other big hurdle was to find a small molecule that would fluoresce only when we wanted it to and would not be toxic to cells."
They tried a number of molecules, most of which stuck to oily lipids in the cell membrane and started fluorescing, or they would kill the cell. Finally, the team realized that GFP itself had a molecule, a fluorophore, within it that switched its light on when it was bound in a certain way within the protein. They created chemical molecules based on the shape of this fluorophore and then developed an artificial RNA sequence, or "aptamer," that held the fluorophore in exactly the same way that GFP held its fluorophore. They named this RNA "Spinach" for its bright green fluorescence.
The researchers went eve
|Contact: Andrew Klein|
New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College