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 .
The dibenzothiophene (DBT) sulfone monooxygenase BdsA from Bacillus subtilis WU-S2B catalyzes the conversion of DBT sulfone to 2'-hydroxybiphenyl 2-sulfinate. We report the crystal structures of BdsA at a resolution of 2.80 Å.
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.
A biofilter based on light expanded clay aggregate (LECA) and cells of the obligate ethylenediamine tetraacetate (EDTA) destructor Chelativorans oligotrophicus LPM-4 has been developed. The culture steadily maintained a high level of EDTA monooxygenase activity of 180-200 nmol/min/mg of protein during three months. EDTA was converted completely or by 80% at initial concentrations of 0.
A system of primers was designed on the basis of analysis of nucleotide sequences of the emoA gene encoding ethylenediaminetetraacetate (EDTA) monooxygenase, which are deposited in GenBank. This system of primers makes it possible to obtain emoA gene fragments approximately 750 bp long for bacterial destructors of EDTA. Polymerase chain reaction (PCR) of total DNA isolated from enrichment and pure cultures showed that this system can be effectively used for detecting the emoA gene in representatives of Alpha- and Gammaproteobacteria.
EDTA has become a major organic pollutant in the environment because of its extreme usage and resistance to biodegradation. Recently, two critical enzymes, EDTA monooxygenase (EmoA) and NADH:FMN oxidoreductase (EmoB), belonging to the newly established two-component flavin-diffusible monooxygenase family, were identified in the EDTA degradation pathway in Mesorhizobium sp. BNC1.
