Novel Redox-Dependent Esterase Activity (EC 126.96.36.199) for DJ-1: Implications for Parkinson's Disease
Diaz-Sanchez, Angel G.
Dagda, Ruben K.
Dominguez-Solis, Carlos A.
Dagda, Raul Y.
Coronado-Ramirez, Cynthia K.
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Mutations the in human DJ-1 (hDJ-1) gene are associated with early-onset autosomal recessive forms of Parkinson's disease (PD). hDJ-1/parkinsonism associated deglycase (PARK7) is a cytoprotective multi-functional protein that contains a conserved cysteine-protease domain. Given that cysteine-proteases can act on both amide and ester substrates, we surmised that hDJ-1 possessed cysteine-mediated esterase activity. To test this hypothesis, hDJ-1 was overexpressed, purified and tested for activity towards 4-nitrophenyl acetate (pNPA) as mu mol of pNPA hydrolyzed/min/mg . protein (U/mg protein). hDJ-1 showed maximum reaction velocity esterase activity (V-max = 235.10 +/- 12.00 U/mg protein), with a sigmoidal fit (S-0.5 = 0.55 +/- 0.040 mM) and apparent positive cooperativity (Hill coefficient of 2.05 +/- 0.28). A PD-associated mutant of DJ-1 (M26I) lacked activity. Unlike its protease activity which is inactivated by reactive oxygen species (ROS), esterase activity of hDJ-1 is enhanced upon exposure to low concentrations of hydrogen peroxide (< 10 mu M) and plateaus at elevated concentrations (> 100 mu M) suggesting that its activity is resistant to oxidative stress. Esterase activity of DJ-1 requires oxidation of catalytic cysteines, as chemically protecting cysteines blocked its activity whereas an oxido-mimetic mutant of DJ-1 (C106D) exhibited robust esterase activity. Molecular docking studies suggest that C106 and L126 within its catalytic site interact with esterase substrates. Overall, our data show that hDJ-1 contains intrinsic redox-sensitive esterase activity that is abolished in a PD-associated mutant form of the hDJ-1 protein.