Expression of gene encoding rice OsMTI-3a in E. coli

Metallothioneins (MTs) are a group of low molecular weight and cystein-rich proteins that can bind metal ions through their thiol groups. In plant different MT isoforms are present. In this study, in order to study of the role of this protein, the coding sequence of gene encoding OsMTI-3a from rice (Oryza sativa), was cloned in pET41a and transferred into expression host, Escherichia coli strain Rosetta (DE3). After induction with IPTG, considerable amount of recombinant proteins was produced in the soluble fraction of the E.coli transformation. The tolerance of cells expressing recombinant proteins toward either Ni, Cu, Cd and Zn were compared to control by plotting their growth curve. In addition the amount of metal that was removed from medium or accumulated in the cells were determined using atomic adsorption spectroscopy (AAS). The results show that the isoform OsMTI-3a has ability to bind metals as follows: Cd>Ni>Zn>Cu.