Crystal Structure and Solution NMR Studies of Lys48-linked Tetraubiquitin at Neutral pH

Ubiquitin modification of proteins is used as a signal in many cellular processes. Lysine side-chains can be modified by a single ubiquitin or by a polyubiquitin chain, which is defined by an isopeptide bond between the C terminus of one ubiquitin and a specific lysine in a neighboring ubiquitin. Po...

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Bibliographic Details
Published in:Journal of molecular biology 2007-03, Vol.367 (1), p.204-211
Main Authors: Eddins, Michael J., Varadan, Ranjani, Fushman, David, Pickart, Cecile M., Wolberger, Cynthia
Format: Article
Language:English
Subjects:
crystal structure
Crystallography, X-Ray
Hydrogen-Ion Concentration
Lys48-linked
Lysine - chemistry
Magnetic Resonance Spectroscopy
Models, Molecular
Polyubiquitin - chemical synthesis
Polyubiquitin - chemistry
polyubiquitin chains
Protein Conformation
tetraubiquitin
ubiquitin
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Summary:Ubiquitin modification of proteins is used as a signal in many cellular processes. Lysine side-chains can be modified by a single ubiquitin or by a polyubiquitin chain, which is defined by an isopeptide bond between the C terminus of one ubiquitin and a specific lysine in a neighboring ubiquitin. Polyubiquitin conformations that result from different lysine linkages presumably differentiate their roles and ability to bind specific targets and enzymes. However, conflicting results have been obtained regarding the precise conformation of Lys48-linked tetraubiquitin. We report the crystal structure of Lys48-linked tetraubiquitin at near-neutral pH. The two tetraubiquitin complexes in the asymmetric unit show the complete connectivity of the chain and the molecular details of the interactions. This tetraubiquitin conformation is consistent with our NMR data as well as with previous studies of diubiquitin and tetraubiquitin in solution at neutral pH. The structure provides a basis for understanding Lys48-linked polyubiquitin recognition under physiological conditions.
ISSN:0022-2836
1089-8638
DOI:10.1016/j.jmb.2006.12.065