Recent work has indicated that the X-linked Inhibitor of Apoptosis Protein (XIAP), which is a key regulator of programmed cell death, may also function as a cellular copper sensor. Specifically, XIAP regulates intracellular concentrations of the copper exporter COMMD1 and binds copper ions directly. We have characterized the binding of copper to a construct of XIAP containing the BIR2 and BIR3 domains, both of which contain a thiol-rich zinc-binding structural site. Absorption and emission spectroscopic measurements show that Cu(I) binds at both the zinc structural sites within the protein and also at higher affinity, surface-accessible binding sites on the BIR2 domain. Moreover, binding at the BIR2 domain induces protein oligomerization, which is likely to impact the function of XIAP. These results constitute the first spectroscopic evidence for copper-XIAP interactions.<br/>

Spectroscopic characterization of Cu(I) binding at the BIR2 domain of the X-linked Inhibitor of apoptosis protein

249th National Meeting (2015)

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