An active proteolytic fragment of Gonyaulax luciferase

Bioluminescence: from chemical bonds to photons

The biological transformation of chemical to photic energy involves an enzyme-mediated chemiluminescent reaction, in which one of the products exists in an electronically excited state, emitting a photon as it returns to the ground state. The colour of bioluminescence differs in different organisms, ranging from the deep blue (460 nm) of certain crustacea, through the bluish green (490 nm) of some bacteria, the green (530 nm) of mushrooms to the red (about 600 nm) of the railroad worm. In one case, energy transfer has been demonstrated from the enzyme system to material that emits light with a longer wavelength. The energies involved range from about 165 to 250 kJ/einstein (40 to 60 kcal/einstein). Boyle first showed that air was involved in bioluminescence in 1668 in his experiments with an air pump. Over the past 100 years, it has become clear that most if not all bioluminescent systems require molecular oxygen. The recent isolation and characterization of an oxygen-containing (peroxide) enzyme intermediate from the bacterial system is described and a reaction mechanism is postulated. This scheme is compared with other hypothetical mechanisms, in particular those involving a four-membered ring intermediate, a dioxetane, in which the simultaneous cleavage of two bonds leaves one product in an excited state. I shall discuss the special role of luciferases in bioluminescence, especially in flashing mechanisms involving 'precharged' intermediates.

C-terminal region of the active domain enhances enzymatic activity in dinoflagellate luciferase

The dinoflagellate luciferase of Lingulodinium polyedrum has three catalytic domains in its single polypeptide chain (M(r) = 137 kDa), and each 42 kDa domain is enzymatically active. Deletion mutants for N- or C-terminal regions of domain 3 of the luciferase, ranging from 29 to 38 kDa, were constructed and expressed in E. coli cells. The activities of N-terminal deleted mutants were above 20% of wild type, but showed different pH-activity profiles. By contrast, the activities of C-terminal deleted mutants decreased drastically to below 1% of wild type, although their pH-activity profiles and spectra were identical to those of wild type L. polyedrum luciferase. These results indicate that the C-terminal region of this enzyme could be important for the bioluminescence reaction, although based on crystal structure of the luciferase domain, this region does not contain active or regulatory sites.

Cloning and characterization of an active fragment of luciferase from a luminescent marine alga, Pyrocystis lunula

Two marine dinoflagellates, Lingulodinium polyedrum and Pyrocystis lunula, emit light in a reaction involving the enzymatic oxidation of its tetrapyrrole luciferin by molecular oxygen. The characteristic properties of P. lunula luciferase have not been clarified, whereas L. polyedrum luciferase, which has three active domains, has been characterized. A cloned partial cDNA of the P. lunula luciferase encodes an active fragment corresponding to part of domain 2 and all of domain 3 of L. polyedrum luciferase. The homology of the amino acid sequence between the two luciferases in domain 3 is about 84.3%. A recombinant His-tagged luciferase fragment containing domain 3 (Mr = 46 kDa) catalyzed the light-emitting oxidation of luciferin (lambdamax = 474 nm). This protein was purified by a single affinity-chromatography procedure. The pH-activity profile and the bioluminescence spectrum of the recombinant enzyme having a third domain are almost identical to those of an extract from P. lunula cultured in vitro. The recombinant enzyme is active at pH 8.0, although the recombinant enzyme derived from the second domain of L. polyedrum luciferase is inactive at pH 8.0. Substitution of Glu-201 by histidine in the third domain of P. lunula luciferase showed a decrease of activity above pH 7.0, suggesting that histidine residues could be responsible for pH-sensitivity in dinoflagellate luciferase.

Three functional luciferase domains in a single polypeptide chain

We report a unique case of a gene containing three homologous and contiguous repeat sequences, each of which, after excision, cloning, and expression in Escherichia coli, is shown to code for a peptide catalyzing the same reaction as the native protein, Gonyaulax polyedra luciferase (Mr = 137). This enzyme, which catalyzes the light-emitting oxidation of a linear tetrapyrrole (dinoflagellate luciferin), exhibits no sequence similarities to other luciferases in databases. Sequence analysis also reveals an unusual evolutionary feature of this gene: synonymous substitutions are strongly constrained in the central regions of each of the repeated coding sequences.

Cloning, sequencing and expression of dinoflagellate luciferase DNA from a marine alga, Gonyaulax polyedra

The marine dinoflagellate, Gonyaulax polyedra emits light in a reaction involving the enzymatic oxidation of its tetrapyrrole luciferin by molecular oxygen; its luciferase (LCF) single chain has an estimated molecular mass of 130 kDa, and exhibits a circadian rhythm in its activity. A cDNA expression library in the lambda ZAPII vector was constructed from the polyadenylated RNA isolated from the Gonyaulax cells during the early night phase, the time at which LCF synthesis is believed to be greatest. Of the approx. 1.2 . 10(5) phages from the library screened with antibody against Gonyaulax LCF, 13 positive plaques were obtained. The nucleotide sequences of two of the larger inserts (2.4 kb and 1.6 kb in length), both carrying the poly(A) tail, were determined and found to be identical in the overlapping region. When expressed in Escherichia coli, both cDNA clones produced active luciferase. A Northern hybridization using the cDNA as a probe showed that the length of the lcf mRNA is approx. 4.1 kb, sufficiently long to encode the 130 kDa LCF. Analyses of polymerase chain reaction products, prepared using both the cloned cDNA and Gonyaulax chromosomal DNA as templates, indicated that the cloned region of the luciferase gene does not carry any introns. This represents the first dinoflagellate luciferase to be cloned and sequenced; its deduced amino acid sequence bears no significant homologies with that of any other luciferase, or any other sequence in the data base.

Characterization of the bioluminescent organelles in Gonyaulax polyedra (dinoflagellates) after fast-freeze fixation and antiluciferase immunogold staining

To characterize the microsources of bioluminescent activity in the dinoflagellate Gonyaulax polyedra, an immunogold labeling method using a polyclonal antiluciferase was combined with fast-freeze fixation and freeze substitution. The quality of the preservation and the specificity of the labeling were greatly improved compared to earlier results with chemical fixation. Two organelles were specifically labeled: cytoplasmic dense bodies with a finely vermiculate texture, and mature trichocysts, labeled in the space between the shaft and the membrane. The available evidence indicates that the dense bodies are the light-emitting microsources observed in vivo. The dense bodies appear to originate in the Golgi area as cytoplasmic densifications and, while migrating peripherally, come into contact with the vacuolar membrane. Mature organelles protrude and hang like drops in the vacuolar space, linked by narrow necks to the cytoplasm. These structural relationships, not previously apparent with glutaraldehyde fixation, suggest how bioluminescent flashes can be elicited by a proton influx from a triggering action potential propagated along the vacuolar membrane. Similar dense bodies were labeled in the active particulate biochemical fraction (the scintillons), where they were completely membrane bound, as expected if their necks were broken and resealed during extraction. The significance of the trichocyst reactivity remains enigmatic. Both organelles were labeled with affinity-purified antibody, which makes it unlikely that the trichocyst labeling is due to a second antibody of different specificity. But trichocysts are not bioluminescent; the cross-reacting material could be luciferase present in this compartment for some other reason, or a different protein carrying similar antigenic epitopes.

Circadian Changes in Enzyme Concentration Account for Rhythm of Enzyme Activity in Gonyaulax

A circadian rhythm in the activity of luciferase is partly responsible for rhythmic bioluminescence in the dinoflagellate alga Gonyaulax polyedra. The cyclic activity of this enzyme can be attributed to a corresponding rhythm in the concentration of immunologically reactive luciferase protein. Hence protein turnover (synthesis or degradation or both) is used by the endogenous clock to control the daily rhythm of bioluminescence.

Dinoflagellate bioluminescence: a comparative study of invitro components

In vitro bioluminescence components of the dinoflagellates Gonyaulax polyedra, G. tamarensis, Dissodinium lunual, and Pyrocystis noctiluca were studied. The luciferases and luciferins of the four species cross-react in all combinations. All of these species possess high-molecular weight luciferases (200,000-400,000 daltons) with similar pH activity profiles. The active single chains of luciferases from the Gonyaulax species have a MW of 130,000 while those from P. noctiluca and D. lunula have a MW of 60,000. Extractable luciferase activity varies with time of day in the two Gonyaulax species, but not in the other two. A luciferin binding protein (LBP) can easily be extracted from the two Gonyaulax species (MW approximately 120,000 daltons), but none could be detected in extracts of either D. lunula or P. noctiluca. Scintillons are extractable from all four species, but they vary in density and the degree to which activity can be increased by added luciferin. Although the biochemistry of bioluminescence in these dinoflagellates is generally similar, the observations that D. lunula and P. noctiluca apparently lack LBP and have luciferases with low MW single chains require further clarification.