While the molecular structures and functions of many copper-handling proteins have been well characterized, much less is known about specific molecular mechanisms that govern cellular response to changing copper concentrations. Available data indicate that copper homeostasis proteins are regulated at many levels, including transcriptional, translational, and post-translational levels. It has recently been demonstrated that expression of multiple copper binding proteins is transcriptionally regulated by the transcription factor Specificity Protein 1 (Sp1) in response to copper level variations in mammalian cells. In this context, we report herein the spectroscopic characterization of Cu(I) binding to the Sp1 zinc finger (ZF) domains. Despite having different sequences, each ZF domain of Sp1 exhibits similar copper binding character. We show that copper binds with high affinity to all three ZF domains in both the apo- and metal-reconstituted forms even in the presence of the strong copper chelators glutathione and BCA. The results of this work suggest that copper substituted ZF domains might be relevant in the context of copper responsive transcription factors.

Characterization of copper(I) binding to the Sp1 zinc finger domains

251st National Meeting (2016)

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