Luciferases and Light‐emitting Accessory Proteins: Structural Biology

Abstract

Creatures that glow have mesmerised people for aeons. During the last few hundred years, scientists have been trying to reveal exactly how organisms produce this light, or bioluminescence. It has been estimated that approximately 30 or more chemically distinct bioluminescence systems have evolved independently. The luciferase enzymes that catalyse bioluminescent reactions use a variety of different structures to produce light. This article looks at the X‐ray crystal structures known for five different types of luciferases: bacterial, dinoflagellate, firefly, and two classes of coelenterates (anthozoan and hydrozoan). The structures of these enzymes reveal details of how they catalyse bioluminescence reactions, and their remarkable diversity of structure, mechanism and substrate specificity. Two accessory fluorescent proteins are also described. Key Concepts: Luciferases are enzymes that catalyse reactions that produce bioluminescence. Approximately 30 distinct bioluminescent systems have evolved. Bioluminescent reactions all involve oxygenation of a substrate to generate a peroxide intermediate, which then breaks down to give an electronically excited product that emits light. X‐ray crystallographic structures are known for the luciferases in five different bioluminescent systems: bacteria, dinoflagellates, fireflies, hydrozoa and anthozoa. Each of these luciferases has an entirely different molecular structure and catalyzes bioluminescence in a unique way.

Mass spectrometry analysis and transcriptome sequencing reveal glowing squid crystal proteins are in the same superfamily as firefly luciferase

“…Bioluminescence has evolved independently at least 40 times across extant organisms. As a result, luciferase enzymes characterised so far have extremely varied structures, mechanisms and substrate specificities 30 31 32 . It has been thought that each luciferase enzyme from each independently evolved bioluminescent system was unique, with no sequence similarity between enzymes from different lineages 30 33 .…”

Semi-Intrinsic Luminescence in Marine Organisms

“…According to Shimomura [3], photoproteins can be distinguished from luciferases by two general means, not requiring molecular oxygen for light emission and being capable of emitting light proportional to the amount of protein present [68]. Isolated aequorin can appear to emit light only by adding Ca 2+ , and once the reaction is complete the protein does not appear to immediately be available for further reactions [69].…”

In Vivo Analysis of Protein–Protein Interactions with Bioluminescence Resonance Energy Transfer (BRET): Progress and Prospects

“…The most typical Lux system is from Photorhabdus luminescens , and it is coded by lux operon, which consists of a series of five genes controlled by a single promoter (Figure 2). In lux operon, luxA and luxB code the bacterial luciferase LuxAB, which is a dimeric luciferase with two subunits sized at 40 and 37 kDa [81]. LuxAB catalyses the oxidization of long-chain fatty aldehyde, such as decanal, and FMNH 2 to produce cyan coloured light that has a peak emission at 490 nm.…”