Synthetic Uncleavable Ubiquitinated Proteins Dissect Proteasome Deubiquitination and Degradation, and Highlight Distinctive Fate of Tetraubiquitin

Sumeet K. Singh, Indrajit Sahu, Sachitanand M. Mali, Hosahalli P. Hemantha, Oded Kleifeld, Michael H. Glickman, Ashraf Brik

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Various hypotheses have been proposed regarding how chain length, linkage type, position on substrate, and susceptibility to deubiquitinases (DUBs) affect processing of different substrates by proteasome. Here we report a new strategy for the chemical synthesis of ubiquitinated proteins to generate a set of well-defined conjugates bearing an oxime bond between the chain and the substrate. We confirmed that this isopeptide replacement is resistant to DUBs and to shaving by proteasome. Analyzing products generated by proteasomes ranked how chain length governed degradation outcome. Our results support that (1) the cleavage of the proximal isopeptide bond is not a prerequisite for proteasomal degradation, (2) by overcoming trimming at the proteasome, tetraUb is a fundamentally different signal than shorter chains, and (3) the tetra-ubiquitin chain can be degraded with the substrate. Together these results highlight the usefulness of chemistry to dissect the contribution of proteasome-associated DUBs and the complexity of the degradation process.

Original languageEnglish
Pages (from-to)16004-16015
Number of pages12
JournalJournal of the American Chemical Society
Volume138
Issue number49
DOIs
StatePublished - 14 Dec 2016
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry

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