The second cysteine‐rich domain of Mac1p is a potent transactivator that modulates DNA binding efficiency and functionality of the protein

Mac1p is a Saccharomyces cerevisiae DNA binding transcription factor that activates genes involved in copper uptake. A copper-induced N^C-terminal intramolecular interac- tion and copper-independent homodimerization affect its func- tion. Here, we present a functional analysis of Mac1p deletion derivatives that attributes new roles to the second cysteine-rich (REPII) domain of the protein. This domain exhibits the copper- responsive potent transactivation function when assayed inde- pendently and, in the context of the entire protein, modulates the efficiency of Mac1p binding to DNA. The efficiency of binding to both copper-response promoter elements can determine the in vivo functionality of Mac1p independent of homodimer- ization. fl 2001 Federation of European Biochemical Soci- eties. Published by Elsevier Science B.V. All rights reserved.