Exploring and exploiting firefly and coelenterate luciferin biosynthesis
Firefly luciferin is a specialized metabolite restricted to fireflies (family Lampyridae) and other select families of beetles (order Coleoptera). Firefly luciferin undergoes luciferase-catalyzed oxidation to produce light, thereby enabling the luminous mating signals essential for reproductive success in many bioluminescent beetle species. Although firefly luciferin and luciferase have become widely used biotechnological tools, questions remain regarding the physiology and biochemistry of firefly bioluminescence. Here we report sulfoluciferin to be an in vivo derivative of firefly luciferin in fireflies, and report the cloning of luciferin sulfotransferase (LST) from the North American firefly Photinus pyralis. LST catalyzes the production of sulfoluciferin from firefly luciferin and the sulfo-donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS). Sulfoluciferin is abundant in several surveyed firefly genera, as well as the bioluminescent elaterid beetle Pyrophorus luminosus at a low level. LST is one of the most highly expressed genes in the Photinus pyralis photophore. Molecular phylogenetics of the LST gene combined with analyses of gene loci in the draft Photinus pyralis genome demonstrate that LST arose from a tandem duplication of an ancestral sulfotransferase gene, which we dub ST0. We propose that the LST gene arose early in the evolution of the Lampyridae by gene duplication and subsequently specialized to catalyze luciferin sulfonation. We hypothesize that sulfoluciferin may serve as a luciferin storage molecule in fireflies, and that LST may find use as a new tool to enhance existing biotechnological applications of the firefly bioluminescent system.
Arnold O. Beckman exemplifies the meaning of the word humanitarian. Combined with his unwavering enthusiasm for life, his keen sense of humor and his strong moral and ethical principles, he is a national icon.