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Updated: Jun 17, 2026
In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Crystallographic structure of ubiquitin in complex with cadmium ions
Insaf A Qureshi1, Francois Ferron, Cheah Chen Seh
1School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
Background:
Ubiquitination plays a critical role in regulating many cellular processes, from DNA repair and gene transcription to cell cycle and apoptosis. It is catalyzed by a specific enzymatic cascade ultimately leading to the conjugation of ubiquitin to lysine residues of the target protein that can be the ubiquitin molecule itself and to the formation of poly-ubiquitin chains.
Findings:
We present the crystal structure at 3.0 A resolution of bovine ubiquitin crystallized in presence of cadmium ions. Two molecules of ubiquitin are present in the asymmetric unit. Interestingly this non-covalent dimeric arrangement brings Lys-6 and Lys-63 of each crystallographically-independent monomer in close contact with the C-terminal ends of the other monomer. Residues Leu-8, Ile-44 and Val-70 that form a hydrophobic patch at the surface of the Ub monomer are trapped at the dimer interface.
Conclusions:
The structural basis for signalling by poly-Ub chains relies on a visualization of conformations of alternatively linked poly-Ub chains. This arrangement of ubiquitin could illustrate how linkages involving Lys-6 or Lys-63 of ubiquitin are produced in the cell. It also details how ubiquitin molecules can specifically chelate cadmium ions.
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