Figure 1. Firefly luciferase and CG6178 both have promiscuous adenylation activity.
a) Fluc adenylates d-luciferin, and subsequent reaction with oxygen forms an excited-state oxyluciferin, which emits light. CG6178 is incapable of adenylating d-luciferin and has no luciferase activity. b) CG6178 natively functions as a promiscuous long-chain fatty acyl-CoA synthetase (ACSL), ligating coenzyme A to C8-C20 fatty acids via an adenylated intermediate. Fluc also has ACSL activity. c) Both Fluc and CG6178 have luciferase activity with CycLuc2.