Conservation of Oxidative Protein Stabilization in an Insect Homologue of Parkinsonism-Associated Protein DJ-1

Abstract

DJ-1 is a conserved, disease-associated protein that protects against oxidative stress and mitochondrial damage in multiple organisms. Human DJ-1 contains a functionally essential cysteine residue (Cys106) whose oxidation is important for regulating protein function by an unknown mechanism. This residue is well conserved in other DJ-1 homologues, including two (DJ-1α and DJ-1β) in Drosophila melanogaster. Because D. melanogaster is a powerful model system for studying DJ-1 function, we have determined the crystal structure and impact of cysteine oxidation on Drosophila DJ-1β. The structure of D. melanogaster DJ-1β is similar to that of human DJ-1, although two important residues in the human protein, Met26 and His126, are not conserved in DJ-1β. His126 in human DJ-1 is substituted with a tyrosine in DJ-1β, and this residue is not able to compose a putative catalytic dyad with Cys106 that was proposed to be important in the human protein. The reactive cysteine in DJ-1 is oxidized readily to the cysteine-sulfinic acid in both flies and humans and this may regulate the cytoprotective function of the protein. We show that the oxidation of this conserved cysteine residue to its sulfinate form (Cys-SO2−) results in considerable thermal stabilization of both Drosophila DJ-1β and human DJ-1. Therefore, protein stabilization is one potential mechanism by which cysteine oxidation may regulate DJ-1 function in vivo. More generally, most close DJ-1 homologues are likely stabilized by cysteine-sulfinic acid formation but destabilized by further oxidation, suggesting that they are biphasically regulated by oxidative modification.

DJ-1-Dependent Regulation of Oxidative Stress in the Retinal Pigment Epithelium (RPE)

“…Our results, together with previous reports, suggests that DJ-1 C oxidation is important for protein stabilization [61], [62], [63], [64] and mitochondria localization [23], [52], [65].…”

A role for the Parkinson’s disease protein DJ-1 as a chaperone and antioxidant in the anhydrobiotic nematode Panagrolaimus superbus

“…These authors proposed that DJ-1 functions as a redox-sensitive molecular chaperone that possesses chaperone activity only in an oxidizing environment. The mechanism by which cysteine oxidation alters human DJ-1 function is unclear because the crystal structures of reduced and Cys106-sulfinate-oxidised hDJ-1 proteins are 'essentially identical' (Lin et al 2012). We find that incubation of PsuDJ-1.1 with insulin in the presence of DTT results in a Fig.…”

“…The crystal structures of E. coli YajL (Wilson et al 2005) and Drosophila melanogaster DJ-1β (Lin et al 2012) are strikingly similar to that of hDJ-1-all three molecules form homodimer structures with similar oxidative modification occurring at the nucleophile elbow of the conserved Cys106 residue (Wilson 2011). Thus, a conservation of structure, and possibly function, occurs within the DJ-1 clade.…”

“…Slight but statistically insignificant increases in transcription levels occurred in response to osmotic stress (2.2-fold), cold (1.8-fold), oxidative stress (1.5 fold) and heat (1.1-fold). DJ-1 is widely associated with the response to oxidative stress (Taira et al 2004;Lin et al 2012;Tsushima et al 2012), so its minimal response to oxidative stress in P. superbus is surprising. Instead, the potent induction of Psudj-1.1 in response to desiccation suggests that a major function of DJ-1.1 in P. superbus may be in anhydrobiotic protection.…”

“…However, in PsuDJ-1.1 and D. melanogaster DJ-1β, this His126 residue is replaced by Tyr (Fig. 3), which would prevent a hydrogen-bonding interaction with the catalytic cysteine residue (Lin et al 2012). This provides structural evidence that PsuDJ-1.1 is unlikely to function as a protease, although further studies with PsuDJ-1.1 lacking the C-terminal region would be necessary to confirm this.…”