Enhanced metallosorption of Escherichia coli cells due to surface display of beta- and alpha-domains of mammalian metallothionein as a fusion to lambprotein

The lamB gene was inserted at with DNA fragments encoding N-terminal beta- and C-terminal alpha-domains of human metallothionein 1A (HMT1A). The hybri d LamB proteins were expressed as full-length products. Virtually whole poo l of hybrid LamB proteins was found localized in the outer membrane of E. c oli to and cells expressing LamB variants retained sensitivity to lambda ph age, indicating their correct folding. Expression of hybrid LamB proteins i ncreased natural ability of E. coli accumulate bivalent heavy metals ions w ith the highest efficiency observed for cadmium. The order of amount of cad mium accumulated is alpha-domain of HMT1A > HMT1A >> beta-domain of HMT1A. This correlates with affinity for cadmium and stability of metallothionein and its individual domains. This confirms suitability of LamB vehicle for s urface display of various bioactive molecules and suggests possibility of e ngineering of cell surface for bioremediation of heavy metals.