Dinoflagellate luciferase | |||||||||
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Identifiers | |||||||||
EC no. | 1.13.12.18 | ||||||||
CAS no. | 303183-71-3 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
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Dinoflagellate luciferase (EC 1.13.12.18, Gonyaulax luciferase) is a specific luciferase, an enzyme with systematic name dinoflagellate-luciferin:oxygen 132-oxidoreductase. [1] [2] [3] [4] [5] [6]
The EC number of dinoflagellate luciferase is 1.13.12.18. This number denotes that dinoflagellate luciferase is an oxidoreductase that acts on single donors with incorporation of molecular oxygen (oxygenases) that are not necessarily derived from O2, with incorporation of one atom of oxygen (internal monooxygenases or internal mixed-function oxidases). [7]
Dinoflagellate luciferase is a single protein with three luciferase domains and an N-terminal domain. [6] The three domains have been shown to be 1.8-A crystal structure that contain beta barrel pocketa that act as active sites with each domain preceded by a regulatory three helix bundle. [6] These helical bundles contain important histidine residues that play a role in the pH regulation of dinoflagellate luciferase activity. [6] Specifically, the presence of N-terminal intramolecularly conserved histidine residues are shown to be responsible for the loss of activity of the enzyme at high pH. [8] Protonation of these histidine residues alters the conformation of each domain to allow the substrate luciferin to enter the enlarged pocket. This conformational change must occur in order to provide access and space for the ligand to enter the active site. [6] At pH 8, the histidine residues remain unprotonated, interacting with a network of hydrogen bonds that block substrate access to the active site. [6] This blockage is overcome by protonation of histidine residues or by experimental replacement of histidine residues with alanine residues. [6] Realistically, alanine replacement does not occur spontaneously; however, this experimental result provides further evidence that the larger histidine residues block access to the active site of the enzyme. The N-terminal domain is conserved between dinoflagellate luciferase and luciferin binding proteins. This region may be where luciferin binding proteins interact with luciferase in order to allow the ligand, usually luciferin, to enter the active site. [9]
Dinoflagellate luciferase is active in slightly acidic environments but in most cases requires the luciferin binding protein (LBP) to unbind from the dinoflagellate luciferin substrate; however, LBP binds luciferin at neutral to alkaline conditions. [10] Although the primary mechanism is unknown, voltage-gated ion channels on scintillon membranes open, allowing an influx of protons to enter the organelle lowering the pH sufficiently for dinoflagellate luciferase to activate. [11] G-protein coupled receptors and calcium ions also play a role in stimulating bioluminescence. [12]
Dinoflagellate luciferase is found in bioluminescent dinoflagellates, eukaryotic protists that are found in ocean surface waters. [13] Dinoflagellate luciferase allows these organisms to emit blue light (max 475 nm) after stimulation. [14] The light produced is theorized to act as a defense against predators or lure for prey. [15] These organisms utilize scintillons which are specialized organelles that project from the cytoplasm into the acidic vacuole to produce this light. [16] This is where the dinoflagellate luciferase enzyme is contained.
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.
Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words luciferin and luciferase, for the substrate and enzyme, respectively. Both words are derived from the Latin word lucifer, meaning "lightbearer", which in turn is derived from the Latin words for "light" (lux) and "to bring or carry" (ferre).
Luciferin is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen. The resulting transformation, which usually involves splitting off a molecular fragment, produces an excited state intermediate that emits light upon decaying to its ground state. The term may refer to molecules that are substrates for both luciferases and photoproteins.
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Renilla-luciferin 2-monooxygenase, Renilla luciferase, or RLuc, is a bioluminescent enzyme found in Renilla reniformis, belonging to a group of coelenterazine luciferases. Of this group of enzymes, the luciferase from Renilla reniformis has been the most extensively studied, and due to its bioluminescence requiring only molecular oxygen, has a wide range of applications, with uses as a reporter gene probe in cell culture, in vivo imaging, and various other areas of biological research. Recently, chimeras of RLuc have been developed and demonstrated to be the brightest luminescent proteins to date, and have proved effective in both noninvasive single-cell and whole body imaging.
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John Woodland "Woody" Hastings, was a leader in the field of photobiology, especially bioluminescence, and was one of the founders of the field of circadian biology. He was the Paul C. Mangelsdorf Professor of Natural Sciences and Professor of Molecular and Cellular Biology at Harvard University. He published over 400 papers and co-edited three books.
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Bioluminescent bacteria are light-producing bacteria that are predominantly present in sea water, marine sediments, the surface of decomposing fish and in the gut of marine animals. While not as common, bacterial bioluminescence is also found in terrestrial and freshwater bacteria. These bacteria may be free living or in symbiosis with animals such as the Hawaiian Bobtail squid or terrestrial nematodes. The host organisms provide these bacteria a safe home and sufficient nutrition. In exchange, the hosts use the light produced by the bacteria for camouflage, prey and/or mate attraction. Bioluminescent bacteria have evolved symbiotic relationships with other organisms in which both participants benefit close to equally. Another possible reason bacteria use luminescence reaction is for quorum sensing, an ability to regulate gene expression in response to bacterial cell density.
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