title: Blocking the entrance of AMP pocket results in hormetic stimulation of imidazolium-based ionic liquids to firefly luciferase.
abstract: The hormesis characterized by low-concentration stimulation and high-concentration inhibition has gained significant interest over the past decades. Some organic solvents and ionic liquids (ILs) have hormetic concentration responses (HCR) to bioluminescence such as firefly luciferase and Vibrio qinghaiensis sp.-Q67. In this study, we determine the effects of 1-alkyl-3-methylimidazolium chlorine ILs ([Cnmim]Cl, n=2, 4, 6, 8, 10 and 12) to firefly luciferase in order to verify the mechanism of hormesis. The luminescence inhibition toxicity tests show that the stimulation effects of [C8mim]Cl and [C10mim]Cl are obvious, [C6mim]Cl and [C12mim]Cl are minor, and [C2mim]Cl and [C4mim]Cl are rare. The enzyme kinetics show that [C8mim]Cl and [C10mim]Cl are the competitive inhibitors with ATP while [C2mim]Cl and [C4mim]Cl are the noncompetitive ones. Molecular dynamics simulation results reveal that imidazolium rings of [C8mim] and [C10mim] locate at the entrance of luciferin pocket which is adjacent to AMP pocket, while alkyl-chains insert into the bottom of the luciferin pocket. Combining the results from inhibition test, kinetics assay and molecular simulation, we can deduce that occupying AMP pocket by imidazolium ring is responsible for hormetic stimulation.
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Fu
authors.initials: F
authors.lastname: Chen
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: ssliuhl@263.net.
authors.forename: Shu-Shen
authors.initials: SS
authors.lastname: Liu
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Mo
authors.initials: M
authors.lastname: Yu
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Rui
authors.initials: R
authors.lastname: Qu
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors.forename: Meng-Chao
authors.initials: MC
authors.lastname: Wang
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D059165:Hormesis / Q000187:drug effects*; D007093:Imidazoles / Q000737:chemistry* / Q000633:toxicity*; D052578:Ionic Liquids / Q000737:chemistry* / Q000633:toxicity*; D007700:Kinetics; D049409:Luciferases, Firefly / Q000737:chemistry* / Q000378:metabolism; D049449:Luminescence; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D018675:Toxicity Tests
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D000249:Adenosine Monophosphate; D049409:Luciferases, Firefly
keywords: Competitive inhibitor; Hormetic concentration response; Ionic liquid; Luciferase; Molecular dynamics simulation