Linkage via K27 Bestows Ubiquitin Chains with Unique Properties among Polyubiquitins

Carlos A Castañeda (Lead / Corresponding author), Emma K Dixon, Olivier Walker, Apurva Chaturvedi, Mark A Nakasone, Joseph E Curtis, Megan R Reed, Susan Krueger, T Ashton Cropp, David Fushman (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


Polyubiquitination, a critical protein post-translational modification, signals for a diverse set of cellular events via the different isopeptide linkages formed between the C terminus of one ubiquitin (Ub) and the ɛ-amine of K6, K11, K27, K29, K33, K48, or K63 of a second Ub. We assembled di-ubiquitins (Ub2) comprising every lysine linkage and examined them biochemically and structurally. Of these, K27-Ub2 is unique as it is not cleaved by most deubiquitinases. As this remains the only structurally uncharacterized lysine linkage, we comprehensively examined the structures and dynamics of K27-Ub2 using nuclear magnetic resonance, small-angle neutron scattering, and in silico ensemble modeling. Our structural data provide insights into the functional properties of K27-Ub2, in particular that K27-Ub2 may be specifically recognized by K48-selective receptor UBA2 domain from proteasomal shuttle protein hHR23a. Binding studies and mutagenesis confirmed this prediction, further highlighting structural/recognition versatility of polyubiquitins and the potential power of determining function from elucidation of conformational ensembles.

Original languageEnglish
Pages (from-to)423-436
Number of pages14
Issue number3
Early online date16 Feb 2016
Publication statusPublished - 1 Mar 2016


  • Binding Sites
  • DNA Repair Enzymes/chemistry
  • DNA-Binding Proteins/chemistry
  • Humans
  • Lysine/metabolism
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Polyubiquitin/chemistry
  • Protein Binding
  • Protein Conformation
  • Scattering, Small Angle
  • Ubiquitination


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