Download MendeleyStructure of S5a Bound to Monoubiquitin Provides a Model for Polyubiquitin Recognition
Wang, Q., Young, P., Walters, K.J.(2005) J Mol Biology 348: 727-739
- PubMed: 15826667
- DOI: https://doi.org/10.1016/j.jmb.2005.03.007
- Primary Citation of Related Structures:
1YX4, 1YX5, 1YX6 - PubMed Abstract:
Ubiquitin is a key regulatory molecule in diverse cellular events. How cells determine the outcome of ubiquitylation remains unclear; however, a likely determinant is the specificity of ubiquitin receptor proteins for polyubiquitin chains of certain length and linkage. Proteasome subunit S5a contains two ubiquitin-interacting motifs (UIMs) through which it recruits ubiquitylated substrates to the proteasome for their degradation. Here, we report the structure of S5a (196-306) alone and complexed with two monoubiquitin molecules. This construct contains the two UIMs of S5a and we reveal their different ubiquitin-binding mechanisms and provide a rationale for their unique specificities for different ubiquitin-like domains. Furthermore, we provide direct evidence that S5a (196-306) binds either K63-linked or K48-linked polyubiquitin, and in both cases prefers longer chains. On the basis of these results we present a model for how S5a and other ubiquitin-binding proteins recognize polyubiquitin.
Organizational Affiliation:
Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church St SE, Minneapolis, MN 55455, USA.
