Work

Structural and biochemical characterization of EDTA monooxygenase and its physical interaction with a partner flavin reductase

Year: 2016

Type: article

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 .

Source: Molecular Microbiology

DOI: 10.1111/mmi.13363

Authors: Se‐Young Jun, Kevin M. Lewis, Buhyun Youn, Luying Xun, ChulHee Kang

Institutions: Washington State University, Pusan National University

Language: English

Topic: Enzyme Structure and Function

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, National Institutes of Health, National Institute of General Medical Sciences

Award: Roles of Calsequestrin in the Control of Calcium Signals in Health and Disease