The Delta33-35 Mutant alpha-Domain Containing beta-Domain-Like M(3)S(9) Cluster Exhibits the Function of alpha-Domain with M(4)S(11) Cluster in Human Growth Inhibitory Factor.

Neuronal growth inhibitory factor (GIF), also known as metallothionein (metallothionein-3), impairs the survival and neurite formation of cultured neurons. It is known that the alpha-beta domain-domain interaction of hGIF is crucial to the neuron growth inhibitory bioactivity although the exact mechanism is not clear. Herein, the beta(MT3)-beta(MT3) mutant and the hGIF-truncated Delta33-35 mutant were constructed, and their biochemical properties were characterized by pH titration, EDTA, and DTNB reactions. Their inhibitory activity toward neuron survival and neurite extension was also examined. We found that the Delta33-35 mutant alpha-domain containing beta-domain-like M(3)S(9) cluster exhibits the function of alpha-domain with M(4)S(11) cluster in hGIF. These results showed that the stability and solvent accessibility of the metal-thiolate cluster in beta-domain is very significant to the neuronal growth inhibitory activity of hGIF and also indicated that the particular primary structure of alpha-domain is pivotal to domain-domain interaction in hGIF.