Structural basis for the selection of glycosylated substrates by SCFFbs1 ubiquitin ligase
Mizushima, T., Yoshida, Y., Kumanomidou, T., Hasegawa, Y., Suzuki, A., Yamane, T., Tanaka, K.(2007) Proc Natl Acad Sci U S A 104: 5777-5781
- PubMed: 17389369 
- DOI: https://doi.org/10.1073/pnas.0610312104
- Primary Citation of Related Structures:  
2E31, 2E32, 2E33 - PubMed Abstract: 
The ubiquitin ligase complex SCF(Fbs1), which contributes to the ubiquitination of glycoproteins, is involved in the endoplasmic reticulum-associated degradation pathway. In SCF ubiquitin ligases, a diverse array of F-box proteins confers substrate specificity. Fbs1/Fbx2, a member of the F-box protein family, recognizes high-mannose oligosaccharides. To elucidate the structural basis of SCF(Fbs1) function, we determined the crystal structures of the Skp1-Fbs1 complex and the sugar-binding domain (SBD) of the Fbs1-glycoprotein complex. The mechanistic model indicated by the structures appears to be well conserved among the SCF ubiquitin ligases. The structure of the SBD-glycoprotein complex indicates that the SBD primarily recognizes Man(3)GlcNAc(2), thereby explaining the broad activity of the enzyme against various glycoproteins. Comparison of two crystal structures of the Skp1-Fbs1 complex revealed the relative motion of a linker segment between the F-box and the SBD domains, which might underlie the ability of the complex to recognize different acceptor lysine residues for ubiquitination.
Organizational Affiliation: 
Department of Biotechnology, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.