Spectroscopic characterization of the copper(I)‐thiolate cluster in the DNA‐binding domain of yeast ACE1 transcription factor

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Abstract
A polypeptide containing the amino‐terminal region of ACEI (residues 1–122; 122*), the activator of yeast Cu‐methallothionein gene transcription, shows charge‐transfer and metal‐centered UV absorption bands, and orange luminescence which are characteristic of Cu‐cysteinyl thiolate cluster structures. These spectral features are abolished by the Cu(1) complexing agents CN* and diethyldithiocarbamate or exposure to acid, but not by the Cu(II)chelator. EDTA. Binding of the polypeptide to its specific DNA recognition site, but not to calf‐thymus double‐stranded DNA, induces quenching of its Tyr and Cu‐S cluster luminescence emission. The CD spectrum is characteristic of a tightly folded structure that may be organized around the Cu cluster.