Study of the Substrate Specificity of Ubiquitin C-Terminal Hydrolase
Date Issued
2014
Date
2014
Author(s)
Liao, Wan-Jyun
Abstract
In eukaryotes, NEDD8 (neural precursor cell expressed developmentally downregulated protein 8) is the most close relative to ubiquitin (Ub) among several kinds of ubiquitin-like proteins. However, Ub and NEDD8 have their unique enzyme systems involved in different cellular pathways. Most of ubiquitinating enzymes (DUB) are specific for Ub, whereas the UCH family is reported to have NEDD8 cross-reactivity. This work is aimed to study the substrate recognition and catalytic mechanism of UCH for processing Ub and NEDD8. It is reported that the length of the active-site crossover loop defines the substrate specificity of UCH for ubiquitin chains. Thus, this study examined whether the length of the active-site crossover loop was also involved in the substrate specificity of UCH. The result showed that mutation of the active-site crossover loop did not impede UCH’s catalytic activity. To investigate whether the replacement of the conserved amino acid residues of Ub with the corresponding residues of NEDD8 may affect the substrate specificity, mutations of the residues at position 4, 12, 14, 63, 64 and 72 were applied to test the possibility. The experimental results demonstrated that the conserved amino acid residues at residues 4, 12, 14, 63, 64 and 72 were not the molecular determinants for substrate binding and specific recognition.
Subjects
泛素
NEDD8
Deubiquitinating enzyme
UCH
Type
thesis
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