The Erbin PDZ Domain Binds with High Affinity and Specificity to the Carboxyl Termini of δ-Catenin and ARVCF

Abstract

Erbin is a recently described member of the LAP (leucine-rich repeat and PDZ domain) protein family. We used a C-terminally displayed phage peptide library to identify optimal ligands for the Erbin PDZ domain. Phage-selected peptides were type 1 PDZ ligands that bound with high affinity and specificity to the Erbin PDZ domain in vitro. These peptides most closely resembled the C-terminal PDZ domain-binding motifs of three p120-related catenins: ␦-catenin, ARVCF, and p0071 (DSWV-COOH). Analysis of the interactions of the Erbin PDZ domain with synthetic peptides matching the C termini of ARVCF or ␦-catenin also demonstrated specific high affinity binding. We characterized the interactions between the Erbin PDZ domain and both ARVCF and ␦-catenin in vitro and in vivo. The Erbin PDZ domain co-localized and coprecipitated with ARVCF or ␦-catenin complexed with ␤-catenin and E/N-cadherin. Mutagenesis and peptide competition experiments showed that the association of Erbin with the cadherincatenin complex was mediated by the interaction of its PDZ domain with the C-terminal PDZ domain-binding motifs (DSWV-COOH) of ARVCF and ␦-catenin. Finally, we showed that endogenous ␦-catenin and Erbin co-localized in and co-immunoprecipitated from neurons. These results suggest that ␦-catenin and ARVCF may function to mediate the association of Erbin with the junctional cadherin-catenin complex. They also demonstrate that C-terminal phage-display technology can be used to predict physiologically relevant ligands for PDZ domains.PDZ 1 domains are 80 -100-amino acid compact globular motifs that are usually embedded in larger multidomain scaffolding proteins (1-3). PDZ domains predominantly mediate protein/protein interactions by recognizing the C termini of various intracellular and cell-surface proteins. Type 1 PDZ domains interact with the C-terminal consensus sequence X(S/ T)X(V/I/L)-COOH, whereas type 2 domains bind to the C-terminal consensus sequence X-hydrophobe-X-hydrophobe-COOH (3-5). Structural analyses of peptides bound to PDZ domains suggest necessary interactions at both positions 0 and Ϫ2 (6-8). However, among type 1 PDZ ligands, these residues are relatively invariant, indicating that other residues within the C terminus likely contribute to the specificity of PDZ domain/ ligand interactions (3). For example, two previous studies (9 -11), as well as those presented here, demonstrated the importance of residues Ϫ1 and Ϫ3 for binding specificity and affinity for some PDZ domain/ligand interactions.Genetic evidence supports a role for several families of PDZ domain-containing proteins as scaffolding molecules that target signaling complexes to various subcellular locations. For example, the multi-PDZ domain protein INAD was found to assemble components of the Drosophila visual transduction system to allow for efficient signaling in response to light (12, 13). Another study in the nematode Caenorhabditis elegans demonstrated that the basolateral localization of the LET-23 receptor tyrosine kinase is dependent upon direct b...

A flexible docking scheme to explore the binding selectivity of PDZ domains

“…The affinity of the phage-selected peptide (TGWETWV) binding at a submicromolar level is higher than the affinities measured for the ErbB2 peptide (EYLGLDVPV). 85,86 Overall, incorporating flexibility with ENM-guided REMD runs predicts binding selectivities of PDZ domains very accurately.…”

Erbin regulates NRG1 signaling and myelination

“…Erbin, via the PDZ domain, interacts with integrin␤4, a receptor for laminins, which are the components of extracellular matrix (19), ␦-catenin, a member of the p120 catenin family, which is critical for adherence junction formation (20), and ErbB2 (27), all of which are implicated in myelin formation or regeneration (10,28,29). It also interacts with EBP50, an adherence junction protein implicated in SC motility (24,30).…”

Scribble protein domain mapping reveals a multistep localization mechanism and domains necessary for establishing cortical polarity

“…More is known about the role of PDZ domains in junctional targeting of LAP proteins. The mammalian LAP proteins Erbin and Densin180 show PDZ-mediated interactions with p120-catenins (Izawa et al, 2002a;Izawa et al, 2002b;Jaulin-Bastard et al, 2002;Laura et al, 2002), and Erbin-catenin p0071 colocalize to adherens junctions and desmosomes in cultured epithelial cells (Izawa et al, 2002b;Jaulin-Bastard et al, 2002). Disruption of Erbin-p0071 interactions leads to aberrant cell morphology and disruption of cell-cell contacts (Jaulin-Bastard et al, 2002).…”