Electronic Thesis and Dissertation Repository


Master of Science




Gary S Shaw


The ubiquitin signaling pathway (USP) consists of hundreds of enzymes which are tightly regulated for proper maintenance of intracellular protein level homeostasis. The main goals of this thesis were to characterize the interaction of two proteins involved in the USP, the E3 ubiquitin ligase called parkin, and the Deubiquitinating (DUB) enzyme, ataxin-3. The effect of disease-state substitutions in the parkin ubiquitin-like domain (UbLD) on the interaction with ataxin-3 was investigated through NMR 1H-15N HSQC titration experiments and affinity binding assays. The three UIM regions in ataxin-3bind the hydrophobic patch of parkin UbLD (KD = 680 μM) and are proposed to use a multivalent binding mechanism. The disease-state UbLD proteins (UbLDV15M, UbLDR33Q, UbLDK48A) retain their interaction with ataxin-3. Other DUB enzymes and E3 ligases have been reported to have regulatory interplay, which has triggered interest in studying protein pairings such as ataxin-3 and parkin.

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