title: Solid phase biosensors for arsenic or cadmium composed of A trans factor and cis element complex.
abstract: The presence of toxic metals in drinking water has hazardous effects on human health. This study was conducted to develop GFP-based-metal-binding biosensors for on-site assay of toxic metal ions. GFP-tagged ArsR and CadC proteins bound to a cis element, and lost the capability of binding to it in their As- and Cd-binding conformational states, respectively. Water samples containing toxic metals were incubated on a complex of GFP-tagged ArsR or CadC and cis element which was immobilized on a solid surface. Metal concentrations were quantified with fluorescence intensity of the metal-binding states released from the cis element. Fluorescence intensity obtained with the assay significantly increased with increasing concentrations of toxic metals. Detection limits of 1 μg/L for Cd(II) and 5 μg/L for As(III) in purified water and 10 µg/L for Cd(II) and As(III) in tap water and bottled mineral water were achieved by measurement with a battery-powered portable fluorometer after 15-min and 30-min incubation, respectively. A complex of freeze dried GFP-tagged ArsR or CadC binding to cis element was stable at 4 °C and responded to 5 μg/L As(III) or Cd(II). The solid phase biosensors are sensitive, less time-consuming, portable, and could offer a protocol for on-site evaluation of the toxic metals in drinking water.
authors.affiliation: United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Japan. msrsiddiki@yahoo.com
authors.forename: Mohammad Shohel Rana
authors.initials: MS
authors.lastname: Siddiki
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Ueda
authors.forename: Isamu
authors.initials: I
authors.lastname: Maeda
mesh_terms: D001151:Arsenic / Q000032:analysis* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005612:Freeze Drying / Q000379:methods; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014877:Water Pollution, Chemical / Q000032:analysis
chemical_list: C489527:ArsR protein, E coli; D001426:Bacterial Proteins; C080050:CadC protein, Bacteria; D029968:Escherichia coli Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D002104:Cadmium; D049452:Green Fluorescent Proteins; D001151:Arsenic