Cd(II) and As(III) bioaccumulation by recombinant Escherichia coli expressing oligomeric human metallothioneins

Metallothioneins (MTs) are a family of metal binding proteins. Recombinant Escherichia coli expressing the human MT (hMT-1A) gene was constructed for bioaccumulation of heavy metals. In order to increase protein stability, the glutathione S-transferase (GST) gene was fused with the hMT-1A gene and coexpressed. In order to increase MT expression efficiency and metal binding capacity, two, three or four hMT-1A genes were integrated in series and overexpressed in E. coli. The recombinant E. coli expressing the GST fused trimeric hMT-1A protein exhibited the highest Cd(II) and As(III) bioaccumulation ability, 6.36 mg Cd/g dry cells and 7.59 mg As/g dry cells, respectively.