Alterations of structure and hydrolase activity of parkinsonism-associated human ubiquitin carboxyl-terminal hydrolase L1 variants.
Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is a neuron-specific ubiquitin recycling enzyme. A mutation at residue 93 and polymorphism at residue 18 within human UCH-L1 are linked to familial Parkinson's disease and a decreased Parkinson's disease risk, respectively. Thus, we constructed recombinant human UCH-L1 variants and examined their structure (using circular dichroism) and hydrolase activities. We confirmed that an I93M substitution results in a decrease in kcat (45.6%) coincident with an alteration in alpha-helical content. These changes may contribute to the pathogenesis of Parkinson's disease. In contrast, an S18Y substitution results in an increase in kcat (112.6%) without altering the circular dichroistic spectrum. These data suggest that UCH-L1 hydrolase activity may be inversely correlated with Parkinson's disease risk and that the hydrolase activity is protective against the disease. Furthermore, we found that oxidation of UCH-L1 by 4-hydroxynonenal, a candidate for endogenous mediator of oxidative stress-induced neuronal cell death, results in a loss of hydrolase activity. Taken together, these results suggest that further studies of altered UCH-L1 hydrolase function may provide new insights into a possible common pathogenic mechanism between familial and sporadic Parkinson's disease.
Nishikawa
Kaori
K
Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, 187-8502, Tokyo, Japan.
Li
Hang
H
Kawamura
Ryoichi
R
Osaka
Hitoshi
H
Wang
Yu-Lai
YL
Hara
Yoko
Y
Hirokawa
Takatsugu
T
Manago
Yoshimasa
Y
Amano
Taiju
T
Noda
Mami
M
Aoki
Shunsuke
S
Wada
Keiji
K
D000447:Aldehydes / Q000494:pharmacology; D002942:Circular Dichroism; D003374:Coumarins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009154:Mutation; D010300:Parkinson Disease / Q000201:enzymology / Q000235:genetics*; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000032:analysis / Q000302:isolation & purification; D013869:Thiolester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D043222:Ubiquitin Thiolesterase; D014452:Ubiquitins / Q000378:metabolism
D000447:Aldehydes; D003374:Coumarins; D011994:Recombinant Proteins; D014452:Ubiquitins; C110770:ubiquitin C-terminal 7-amido-4-methylcoumarin; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase; C027576:4-hydroxy-2-nonenal