Dronpa

Function

Dronpa is a GFP-like photoswitchable protein. It was first designed by Ryoko Ando, Hideaki Mizuno, and Atsushi Miyawaki in 2004. The protein was named after the “Japanese term Dron, a ninja term referring to instant disappearance of the body, and pa, short for photo activation.”^[1] Using a laser diode at 405nm the protein can be activated into its “bright” state, and using an argon laser at 480nm, the protein can be deactivated and turned into its “dark” state^[1]. Dronpa can be turned back and forth as often as necessary just by switching the wavelength of light that is focused onto it. Dronpa works by switching between the cis (bright state) to trans (dark state) position of a few amino acids in the chromophore center of the Beta-barrel structure. This reversible ability to be able to switch back and forth between “dark” and “light” is what makes Dronpa unique.

Structural highlights

The amino acids that are key for this change - forming spontaneously the CYG bicyclic chromophore - are Cys 62, Tyr 63, and Gly 64. There are also changes in conformation of four additional amino acids that are near the chromophore, Arg 66, Ser 142, Val 157, and His 193^[2].