中国生物工程杂志

Metallothioneins (MTs) are a family of low-molecularweight, cysteine-rich, metal-binding proteins, widely distributed in nature and have very important functions such as heavy metal detoxification and essential metal metabolism. It is very difficult to express recombinant MT directly because of toxicity to host cells, presumably owing to its thiol groups, and because of general difficulties encountered in expressing small proteins. A DNA coded fusion protein GST-SUMO-MT was constructed and cloned into vector pET-28a. The fusion protein was expressed in E.coli Origami (DE3) and the amount of expressed fusion protein in cultural media using described strategy was 70 mg/L. The fusion protein, GST-SUMO-MT was purified using the combination of Glutathione Sepharose chromatography and Sephardex G-25 and the purity was higher than 95%. GST-SUMO-MT could improve the endurance of host for the accumulation of Cd2+, Zn2+ and Cu2+and the endurance activity was 4.2, 4.0 and 1.6 times than that of control respectively. Moreover, every fusion protein, GST-SUMO-MT, could combine 2-3 Cd2+ detected by Atomic absorption spectrum.