Abstract
Metal-responsive transcription factor-1 (MTF-1) is a transcription factor contains six C2H2 type zinc finger motifs. When cells are exposed to stresses, such as metal and oxidative stress, MTF-1 can be activated and translocates into nuclei. The factor will bind to metal response elements (MREs) and induces gene expressions. We investigated in this study how MTF-1 interacts with MREs. Notably, purified MTF-1 lost its ability to bind MRE even in the presence of Zn. However, addition of cell extract restored the DNA binding activity of MTF-1. We hypothesized that there are factors in cell extract participating in MTF-1 binding reaction. In this study, we attempted to purify and characterize this factor using ion-exchange and gel filtration chromatographies. Our results showed that this factor exists in the nuclei and cytoplasm of eukaryotic cells, and it can also be found in prokaryotic cells. Addition of chaperons, such as Hsp90 and Hsc70 exert the binding ability of MTF-1, raising the possibility that this factor facilitates MTF-1 binding by stabilizing its structure. A variety of proteins have been used to classify the characteristics of the potential MTF-1 binding factor. However, no conclusive result was obtained.