Structure of Cu(I)-Bound DJ‑1 Reveals a Biscysteinate Metal Binding Site at the Homodimer Interface: Insights into Mutational Inactivation of DJ‑1 in Parkinsonism

The Parkinsonism-associated protein
DJ-1 has been suggested to
activate the Cu–Zn superoxide dismutase (SOD1) by providing
its copper cofactor. The structural and chemical means by which DJ-1
could support this function is unknown. In this study, we characterize
the molecular interaction of DJ-1 with Cu­(I). Mass spectrometric analysis
indicates binding of one Cu­(I) ion per DJ-1 homodimer. The crystal
structure of DJ-1 bound to Cu­(I) confirms metal coordination through
a docking accessible biscysteinate site formed by juxtaposed cysteine
residues at the homodimer interface. Spectroscopy in crystallo validates the identity and oxidation state of the bound metal. The
measured subfemtomolar dissociation constant (Kd = 6.41 × 10–16 M) of DJ-1 for Cu­(I)
supports the physiological retention of the metal ion. Our results
highlight the requirement of a stable homodimer for copper binding
by DJ-1. Parkinsonism-linked mutations that weaken homodimer interactions
will compromise this capability.