A metallothionein-like protein of rice (rgMT) functions in E. coli and its gene expression is induced by abiotic stresses.

A metallothionein-like (rgMT) gene was isolated from a rice (Oryza sativa L.) root cDNA library that was prepared from plants grown under NaHCO3 stress. The rgMT gene expression was induced in rice leaves and roots under several abiotic stresses from salts (NaCl and NaHCO3), drought (PEG) and metals (CuCl2, ZnCl2, CdCl2). The results suggested that the rgMT gene was expressed in response to environmental stresses. The rgMT gene was expressed in Escherichia coli, and the final yield of the purified rgMT protein was 4.8 mg g(-1) dry cells. Tolerance of E. coli expressing GST-rgMT fusion protein to Cu2+, Zn2+ and Cd2+ was enhanced, and cells dry weight increased 0.04 mg, 0.17 mg and 0.07 mg in 1 ml culture treated with either CuCl2, ZnCl2 or CdCl2, respectively, compared with control after 6 h culture.