Lanthanum(III) Impacts on Metallothionein MTT1 and MTT2 from Tetrahymena thermophila

Metallothionein MTT1 and MTT2 from Tetrahymena thermophila are sulfydryl-rich proteins that can bind to and are inducible by heavy metals such as mercury, cadmium, zinc, and copper. However, little is known about the induction and binding of T. thermophila metallothionein by trivalent metals. In this study, we found that 10–80 μM La³⁺ can promote Tetrahymena cells proliferation, and fluorescence spectrum analysis showed that La³⁺ can enter T. thermophila cells. Real-time quantitative polymerase chain reaction showed La³⁺ induced the expression of MTT1 and MTT2. Furthermore, Fluorescence analysis indicated La³⁺ bind to MTT1 and MTT2. These results implied that La³⁺ could interact with MTT1 and MTT2 via aspartic or glutamic acid oxygen atoms.