Project description:The widespread use of synthetic aminopolycarboxylates, such as ethylenediaminetetraacetate (EDTA), as chelating agents has led to their contamination in the environment as stable metal-chelate complexes. Microorganisms can transport free EDTA, but not metal-EDTA complexes, into cells for metabolism. An ABC-type transporter for free EDTA uptake in Chelativorans sp. BNC1 was investigated to understand the mechanism of the ligand selectivity. We solved the X-ray crystal structure of the periplasmic EDTA-binding protein (EppA) and analyzed its structure-function relations through isothermal titration calorimetry, site-directed mutagenesis, molecular docking, and quantum chemical analysis. EppA had high affinities for EDTA and other aminopolycarboxylates, which agrees with structural analysis, showing that its binding pocket could accommodate free aminopolycarboxylates. Further, key amino acid residues involved in the binding were identified. Our results suggest that EppA is a general binding protein for the uptake of free aminopolycarboxylates. This finding suggests that bacterial cells import free aminopolycarboxylates, explaining why stable metal-chelate complexes are resistant to degradation, as they are not transported into the cells for degradation.
Project description:The bacterium Novosphingobium sp. THN1 (THN1) is capable of degrading microcystin-LR (MCLR). To get an insight into genes expression during MCLR degradation and the regulation of different carbon concentrations on MCLR degradation, we performed RNA-seq of THN1 during MCLR degradation under different carbon concentrations.
Project description:In this study, we isolated a potent doxycycline-degrading bacterium, Chryseobacterium sp. WX1, from environmental samples. To elucidate the molecular mechanisms underlying doxycycline degradation by strain WX1, we assessed and interpreted the proteomic profiles of Chryseobacterium sp. WX1 under conditions both with and without doxycycline exposure.
