No abstract

Insect bioluminescence is largely confined to a small subset of beetles, most notably the firefly. However, beetle luciferases are thought to have evolved from fatty acyl‐CoA synthetases found in all insects. Both classes of enzymes activate fatty acids with ATP to form acyl‐adenylate intermediates, but only luciferases can activate and oxidize D‐luciferin to emit light. Recently, we found that the Drosophila fatty acyl‐CoA synthetase CG6178, which cannot use D‐luciferin as a substrate, is a latent luciferase due to its ability to catalyze light emission from the synthetic luciferin analog CycLuc2. Bioluminescence can be detected from the purified protein, endogenous CG6178 in live Drosophila Schneider 2 cells, and from mammalian cells transfected with CG6178. Here we show that additional luciferin analogs can support bioluminescence with CG6178, highlighting the generality of the light emitting chemistry and the catalytic promiscuity of this enzyme. We also find that additional insect fatty acyl‐CoA synthetases possess luciferase activity when treated with an appropriate synthetic luciferin. These results demonstrate that the introduction of a new substrate can reveal latent enzymatic activity that differs significantly from an enzyme's normal function and suggest that the chemistry of a small molecule substrate can help drive evolution of new enzymatic functions.