Transcriptome analysis reveals candidate genes involved in luciferin metabolism inLuciola aquatilis(Coleoptera: Lampyridae)

Abstract

Bioluminescence, which living organisms such as fireflies emit light, has been studied extensively for over half a century. This intriguing reaction, having its origins in nature where glowing insects can signal things such as attraction or defense, is now widely used in biotechnology with applications of bioluminescence and chemiluminescence. Luciferase, a key enzyme in this reaction, has been well characterized; however, the enzymes involved in the biosynthetic pathway of its substrate, luciferin, remains unsolved at present. To elucidate the luciferin metabolism, we performed a de novo transcriptome analysis using larvae of the firefly species, Luciola aquatilis. Here, a comparative analysis is performed with the model coleopteran insect Tribolium casteneum to elucidate the metabolic pathways in L. aquatilis. Based on a template luciferin biosynthetic pathway, combined with a range of protein and pathway databases, and various prediction tools for functional annotation, the candidate genes, enzymes, and biochemical reactions involved in luciferin metabolism are proposed for L. aquatilis. The candidate gene expression is validated in the adult L. aquatilis using reverse transcription PCR (RT-PCR). This study provides useful information on the bio-production of luciferin in the firefly and will benefit to future applications of the valuable firefly bioluminescence system.

Enzymatic promiscuity and the evolution of bioluminescence

“…Figure details our current understanding of how fireflies likely synthesize their luciferin from benzoquinone and two molecules of l ‐cysteine. This de novo biosynthetic route involves first removing the sugar from arbutin, yielding 1,4 hydroquinone . The 1,4 hydroquinone is then oxidized to para ‐benzoquinone .…”

“…This de novo biosynthetic route involves first removing the sugar from arbutin, yielding 1,4 hydroquinone . The 1,4 hydroquinone is then oxidized to para ‐benzoquinone . l ‐cysteine adds to benzoquinone through 1,4 addition .…”

“…recently demonstrated that l ‐luciferin can be synthesized in neutral buffer conditions under air atmosphere at room temperature, enzymes likely mediate in vivo d ‐luciferin metabolism . To establish the identities of the enzymes responsible for luciferin metabolism, recent studies have focused on characterization of the transcriptome of fireflies . These studies have uncovered several candidate enzymes that could presumably function in these reactions and have high expression in lantern tissue .…”

RNA Sequencing, De novo assembly, functional annotation and SSR analysis of the endangered diving beetle Cybister chinensis (= Cybister japonicus) using the Illumina platform

“…) revealing the candidate genes involved in stress responses, chemosensory processes, metabolism, and immune processes of insects including the beetles (Vongsangnak et al . ; Duan et al . ; Wei et al .…”

“…Next-generation sequencing (NGS) platforms have been increasingly used to map the genetic regulatory circuits and provide insights to survival and adaptation strategies of commercial and threatened species of insects (Morozova and Marra 2008;Wheat 2010;Patnaik et al 2016). Moreover, the NGS platforms have been useful to generate transcriptome data and analyse the complexity of the transcriptome in nonmodel species of insects (Oppenheim et al 2015;Patnaik et al 2015;Patnaik et al 2016) revealing the candidate genes involved in stress responses, chemosensory processes, metabolism, and immune processes of insects including the beetles (Vongsangnak et al 2016;Duan et al 2017;Wei et al 2017). The Roche 454 FLX Titanium platform-based pyrosequencing technology provided large-scale gene discovery in the coleopteran pest, Eucryptorrhynchus chinensis (Liu and Wen 2016), ground beetles, Carabus iwawakianus and Carabus uenoi (Fujimaki et al 2014), and the banana weevil, Cosmopolites sordidus (Valencia et al 2016).…”