Cloning and characterization of phytochelatin synthase from a Nickel hyperaccumulator Thlaspi japonicum and its expression in yeast

Phytochelatin {γ-(EC)_nG} is a group of peptides that chelate and detoxify heavy metals in plants. However, the relationship between the phytochelatin function and metal-hyperaccumulating plants has not been elucidated. In the current study, we cloned the phytochelatin synthase (PCS) gene, designated as TjPCS, from a Ni-hyperaccumulator plant Thlaspi japonicum, and examined its ability to detoxify Cd^<2+>. The RT-PCR product of 1,745 bp, which contained the open reading frame of the TjPCS was isolated, and cloned. The deduced amino acid sequence of TjPCS (475 amino acid length) showed a 90% identity with the sequence of PCS from Arabidopsis thaliana. The yeast transformed with the TjPCS</sprcial> produced PCS and showed an obvious Cd^<2+> tolerance after the induction of gene expression by galactose