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. Author manuscript; available in PMC: 2016 Jun 1.
Published in final edited form as: Biochem J. 2015 Jun 1;468(2):215–226. doi: 10.1042/BJ20141170

Figure 4. SARS PLpro is a unique “distal di-distributive” deubiquitinating enzyme.

Figure 4

(A) Schematics of the purification strategy of poly-Ub-conjugated Cdc34 in order to asses the directionality of cleavage of Ub chains. (B) Time-course cleavage of HisCdc34-poly-UbFLAG conjugates by SARS and MERS PLpro, revealing stabilization of mono-Ub-conjugated Cdc34 as a cleavage product by SARS PLpro and not by MERS PLpro. (C) Time-course cleavage of HisCdc34-poly-UbFLAG conjugates by USP-family DUBs. (D) Quantification of the relative abundance of the HisCdc34-mono-UbFLAG species from the time-course cleavage assay in (C). (E) Schematic representation of the mono-(for MERS PLpro, USP2 and USP21) and the di-distributive cleavage mechanism (for SARS PLpro), indicating the accumulation of mono-Ub-conjugated substrates only in the case of the di-distributive cleavage mechanism displayed by SARS PLpro.