Structural analysis of Siah1 and its interactions with Siah-interacting protein (SIP).
Seven in absentia homologue (Siah) family proteins bind ubiquitin-conjugating enzymes and target proteins for proteasome-mediated degradation. Recently we identified a novel Siah-interacting protein (SIP) that is a Sgt1-related molecule that provides a physical link between Siah family proteins and the Skp1-Cullin-F-box ubiquitin ligase component Skp1. In the present study, a ... structure-based approach was used to identify interacting residues in Siah that are required for association with SIP. In Siah1 a large concave surface is formed across the dimer interface. Analysis of the electrostatic surface potential of the Siah1 dimer reveals that the beta-sheet concavity is predominately electronegative, suggesting that the protein-protein interactions between Siah1 and SIP are mediated by ionic contacts. The structural prediction was confirmed by site-directed mutagenesis of these electronegative residues, resulting in loss of binding of Siah1 to SIP in vitro and in cells. The results also provide a structural basis for understanding the mechanism by which Siah family proteins interact with partner proteins such as SIP.
Mesh Terms:
Calcium-Binding Proteins, Carrier Proteins, Cell Line, Dimerization, Heat-Shock Proteins, Humans, Models, Molecular, Mutagenesis, Site-Directed, Nuclear Proteins, Protein Binding, Protein Conformation, Ubiquitin-Protein Ligases
Calcium-Binding Proteins, Carrier Proteins, Cell Line, Dimerization, Heat-Shock Proteins, Humans, Models, Molecular, Mutagenesis, Site-Directed, Nuclear Proteins, Protein Binding, Protein Conformation, Ubiquitin-Protein Ligases
J. Biol. Chem.
Date: Jan. 17, 2003
PubMed ID: 12421809
View in: Pubmed Google Scholar
Download Curated Data For This Publication
140402
Switch View:
- Interactions 4