The dark and bright sides of an enzyme: a three dimensional structure of the N-terminal domain of Zophobas morio luciferase-like enzyme, inferences on the biological function and origin of oxygenase/luciferase activity. Issue 5 (21st April 2016)

• Record Type: Journal Article
• Authors: Prado, R. A.; Santos, C. R.; Kato, D. I.; Murakami, M. T.; Viviani, V. R.
• Is Part Of: Photochemical & photobiological sciences. Volume 15:Issue 5(2016:May)
• Page Start: 654
• Page End: 665
• Publication Date: 2016-04-21
• Subjects: Photochemistry -- Periodicals; Photobiology -- Periodicals; 541.35
• DOI: 10.1039/c6pp00017g
• Languages: English
• ISSNs: 1474-905X

Abstract

Abstract : The structure and catalytic activities of a Malpighian luciferase-like enzyme indicate a generalistic xenobiotic CoA-ligase and a catalytic residue for bioluminescence. Abstract : Beetle luciferases, the enzymes responsible for bioluminescence, are special cases of CoA-ligases which have acquired a novel oxygenase activity, offering elegant models to investigate the structural origin of novel catalytic functions in enzymes. What the original function of their ancestors was, and how the new oxygenase function emerged leading to bioluminescence remains unclear. To address these questions, we solved the crystal structure of a recently cloned Malpighian luciferase-like enzyme of unknown function from Zophobas morio mealworms, which displays weak luminescence with ATP and the xenobiotic fireflyd -luciferin. The three dimensional structure of the N-terminal domain showed the expected general fold of CoA-ligases, with a unique carboxylic substrate binding pocket, permitting the binding and CoA-thioesterification activity with a broad range of carboxylic substrates, including short-, medium-chain and aromatic acids, indicating a generalist function consistent with a xenobiotic-ligase. The thioesterification activity withl -luciferin, but not with thed -enantiomer, confirms that the oxygenase activity emerged from a stereoselective impediment of the thioesterification reaction with the latter, favoring the alternative chemiluminescence oxidative reaction. The structure and site-directed mutagenesis support the involvement of the main-chain amide carbonyl of the invariant glycine G323 as the catalytic base for luciferin C4 proton abstraction during the oxygenase activity in this enzyme and in beetle luciferases (G343).