title: Structural and biochemical characterization of EDTA monooxygenase and its physical interaction with a partner flavin reductase.
abstract: Ethylenediaminetetraacetate (EDTA) is currently the most abundant organic pollutant due to its recalcitrance and extensive use. Only a few bacteria can degrade it, using EDTA monooxygenase (EmoA) to initiate the degradation. EmoA is an FMNH2 -dependent monooxygenase that requires an NADH:FMN oxidoreductase (EmoB) to provide FMNH2 as a cosubstrate. Although EmoA has been identified from Chelativorans (ex. Mesorhizobium) sp. BNC1, its catalytic mechanism is unknown. Crystal structures of EmoA revealed a domain-like insertion into a TIM-barrel, which might serve as a flexible lid for the active site. Docking of MgEDTA(2-) into EmoA identified an intricate hydrogen bond network connected to Tyr(71) , which should potentially lower its pKa. Tyr(71) , along with nearby Glu(70) and a peroxy flavin, facilitates a keto-enol transition of the leaving acetyl group of EDTA. Further, for the first time, the physical interaction between EmoA and EmoB was observed by ITC, molecular docking and enzyme kinetic assay, which enhanced both EmoA and EmoB activities probably through coupled channelling of FMNH2 .
authors.affiliation: Department of Chemistry, Washington State University, Pullman, WA, 99164-4630, USA.
authors.forename: Se-Young
authors.initials: SY
authors.lastname: Jun
authors.affiliation: Department of Chemistry, Washington State University, Pullman, WA, 99164-4630, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Lewis
authors.affiliation: Department of Chemistry, Washington State University, Pullman, WA, 99164-4630, USA.|Department of Biological Sciences, Pusan National University, Busan, South Korea.
authors.forename: Buhyun
authors.initials: B
authors.lastname: Youn
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA, 99164-4660, USA.
authors.forename: Luying
authors.initials: L
authors.lastname: Xun
authors.affiliation: Department of Chemistry, Washington State University, Pullman, WA, 99164-4630, USA.|School of Molecular Biosciences, Washington State University, Pullman, WA, 99164-4660, USA.
authors.forename: ChulHee
authors.initials: C
authors.lastname: Kang
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D020134:Catalytic Domain; D004492:Edetic Acid / Q000378:metabolism; D038181:FMN Reductase / Q000737:chemistry* / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000378:metabolism; D005415:Flavins / Q000378:metabolism; D006873:Hydroquinones / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000378:metabolism*; D059127:Phyllobacteriaceae / Q000201:enzymology / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D005415:Flavins; D006873:Hydroquinones; C540087:flavin mononucleotide hydroquinone; D005486:Flavin Mononucleotide; D004492:Edetic Acid; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D000587:Oxidoreductases Acting on CH-NH Group Donors; D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; C113720:EDTA monooxygenase