ENERGY TRANSFER VIA PROTEIN‐PROTEIN INTERACTION IN RENILLA BIOLUMINESCENCE

Abstract—Radiationless energy transfer is known to play biologically important roles in both photosynthesis and bioluminescence. In photosynthesis, accessory pigments serve as “antennae”, transferring excitation energy into the “reaction centers”. In the bioluminescent coelenterates, energy is transferred from the site of reaction via an accessory protein known as the green‐fluorescent protein (GFP). Coelenterate bioluminescence systems such as that of the sea pansy, Renilla, are well characterized biochemically, and their energy transfer process can be duplicated in vitro using isolated and purified components. We have measured efficient in vitro energy transfer from the electronic excited state of the enzyme‐bound oxyluciferin to the green‐fluorescent protein at protein concentrations of 0.1 μM. We have also demonstrated a 1:l complex between these proteins, under conditions of energy transfer, by the chromato‐graphic technique of Hummel and Dreyer. These observations indicate that bioluminescent energy transfer is mediated via protein‐protein interaction. Furthermore, with inter‐species cross‐reaction studies and protein modification techniques we have shown that the interaction between luciferase and GFP is highly specific. These features make the Renilla system an attractive alternative to the photosynthetic systems as a tool for studying radiationless energy transfer.