Nature Biotechnology
18, 661 - 665 (2000)
doi:10.1038/76516
Engineering a mouse metallothionein on the cell surface of Ralstonia eutropha CH34 for immobilization of heavy metals in soilMarc Valls1, 2, Sílvia Atrian1, Víctor de Lorenzo2
& Luis A. Fernández21
Departament de Genètica, Facultat de Biologia, Av. Diagonal 645, Universitat de Barcelona, 08028-Barcelona, Spain
2
Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Campus Cantoblanco, 28049-Madrid. Spain
Correspondence should be addressed to Víctor de Lorenzo vdlorenzo@cnb.uam.esAlcaligenesbioremediationmetallothioneinRalstoniasurface displayheavy metalsHere we describe targeting of the mouse metallothionein I (MT) protein to the cell surface of the heavy metal-tolerant Ralstonia eutropha (formerly Alcaligenes eutrophus) CH34 strain, which is adapted to thrive in soils highly polluted with metal ions. DNA sequences encoding MT were fused to the autotransporter  -domain of the IgA protease of Neisseria gonorrhoeae, which targeted the hybrid protein toward the bacterial outer membrane. The translocation, surface display, and functionality of the chimeric MT protein was initially demonstrated in Escherichia coli before the transfer of its encoding gene (mtb) to R. eutropha. The resulting bacterial strain, named R. eutropha MTB, was found to have an enhanced ability for immobilizing Cd2+ ions from the external media. Furthermore, the inoculation of Cd2+-polluted soil with R. eutropha MTB decreased significantly the toxic effects of the heavy metal on the growth of tobacco plants (Nicotiana bentamiana).
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