New bioluminescence mechanism by luciferin analogue TokeOni

Abstract

Firefly bioluminescence is the most widely used bioluminescence system in the field of bioluminescence imaging. However, the yellow-green light of firefly bioluminescence is not able to penetrate deeper through living organisms. To overcome the problem, we have developed three longer wavelength luciferin analogues, "AkaLumine", "TokeOni" and "SeMpai" based on the substrate of the firefly bioluminescence system. The luminescence induced by these analogues is extremely transmissive to living organisms. Unexpectedly, even though the luminescent enzyme gene was not introduced, we observed the luminescence from the liver of mice in vivo when AkaLumine and TokeOni were administered. In the process of several analyses to elucidate the mechanism of this unknown luminescence phenomenon, we found that inhibitors for some of cytochrome P450s (CYPs) significantly attenuated the luminescence. To investigate whether this luminescence phenomenon is also observed in other animal species, TokeOni was added to the extracts of blow flies and pill bugs. As a result, luminescence was observed in both species, and it was also attenuated by several CYP inhibitors. These results suggest that TokeOni luminescence may be caused by a mechanism involving CYPs in various animal species. On the other hand, it has been reported that a putative fatty acyl CoA synthetase has luminescent activity against several luciferin analogs in fruit flies. We would like to report the results of our investigation into the possible involvement of fatty acyl CoA synthases in the luminescence phenomena by TokeOni.