Interacting selectively and non-covalently with a sequence of DNA that is in cis with and relatively close to a core promoter for RNA polymerase II (RNAP II) and interacting selectively and non-covalently with metal ion(s) and responding, e.g. by conformational change, to changes in the cellular level of metal ion, such a way that metal ion binding regulates the activity of the transcription factor in order to activate or increase the frequency, rate or extent of transcription from the RNAP II promoter.