title: Expression of human metallothionein-2 in Escherichia coli: cadmium tolerance of transformed cells.
abstract: A genetic approach was undertaken to investigate the physiological roles of human metallothionein-2. A constructed expression plasmid, pEXPMTII, in which human metallothionein-IIA cDNA was inserted downstream of a tryptophan-lactose promoter, was used to transform Escherichia coli JM105 strain. Cadmium-binding metallothionein was successfully expressed in E. coli in the medium containing cadmium, while copper and zinc-metallothioneins were scarcely observed in copper- or zinc-containing medium. The amino acid composition and sequence of the biosynthesized cadmium-metallothionein were analyzed. The selectivity of metals bound to metallothionein and the stability of metal-binding forms of metallothionein in E. coli were discussed. In addition, cadmium, zinc, or copper resistance of the cells expressing metallothionein was examined. Cells transformed with the plasmid pEXPMTII and cultured in a medium containing cadmium exhibited tolerance only to cadmium. It was demonstrated that human metallothionein-2 functioned for cadmium detoxification in E. coli.
authors.affiliation: Department of Environmental Medicine and Informatics, Hokkaido University, Sapporo.
authors.forename: F
authors.initials: F
authors.lastname: Odawara
authors.forename: M
authors.initials: M
authors.lastname: Kurasaki
authors.forename: M
authors.initials: M
authors.lastname: Suzuki-Kurasaki
authors.forename: S
authors.initials: S
authors.lastname: Oikawa
authors.forename: T
authors.initials: T
authors.lastname: Emoto
authors.forename: F
authors.initials: F
authors.lastname: Yamasaki
authors.forename: A R
authors.initials: AR
authors.lastname: Linde Arias
authors.forename: Y
authors.initials: Y
authors.lastname: Kojima
mesh_terms: D001483:Base Sequence; D002104:Cadmium / Q000494:pharmacology*; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D003300:Copper / Q000378:metabolism; D018076:DNA, Complementary; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D008668:Metallothionein / Q000096:biosynthesis* / Q000302:isolation & purification; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D015183:Restriction Mapping; D015032:Zinc / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D002104:Cadmium; D003300:Copper; D008668:Metallothionein; D015032:Zinc