Ubiquitin is degraded by the ubiquitin system as a monomer and as part of its conjugated target

Nitzan Shabek, Kazuhiro Iwai, Aaron Ciechanover

Research output: Contribution to journalArticleResearchpeer-review

17 Citations (Scopus)

Abstract

An important problem concerning regulation of the ubiquitin-proteasome system (UPS) relates to the stability of its own components and the mechanisms of their degradation. It has been demonstrated that monomeric ubiquitin is relatively stable and is probably degraded by the proteasome. It has also been shown that it is destabilized following inactivation of deubiquitinating enzymes, suggesting that failure to release it, results in its concomitant degradation along with its target. Here, we demonstrate that conjugation of monomeric ubiquitin requires both its internal lysines and N-terminal residue. Interestingly however, the degradation of the monomeric species requires also a short C-terminal extension, implying that unlike conjugation, entry into the proteasomal chamber requires a tail that can be generated in the cell via several distinct mechanisms. We further show that accelerated intracellular degradation induced by stress results in depletion of ubiquitin, supporting the notion that ubiquitin is also degraded as part of the chain conjugated to its target substrate.

Original languageEnglish
Pages (from-to)425-431
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume363
Issue number2
DOIs
StatePublished - 16 Nov 2007

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Ubiquitin
Monomers
Degradation
Proteasome Endopeptidase Complex
Lysine
Substrates
Enzymes

Keywords

  • Degradation
  • Proteasome
  • Ubiquitin

Cite this

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Ubiquitin is degraded by the ubiquitin system as a monomer and as part of its conjugated target. / Shabek, Nitzan; Iwai, Kazuhiro; Ciechanover, Aaron.

In: Biochemical and Biophysical Research Communications, Vol. 363, No. 2, 16.11.2007, p. 425-431.

Research output: Contribution to journalArticleResearchpeer-review

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