Journal Article

Structural insights into substrate recognition by the SOCS2 E3 ubiquitin ligase

Kung, Wei-Wei, Ciulli, Alessio, Makukhin, Nikolai, Bruno, Elvira, Ramachandran, Sarath

2019

Overview

The suppressor of cytokine signaling 2 (SOCS2) acts as substrate recognition subunit of a Cullin5 E3 ubiquitin ligase complex. SOCS2 binds to phosphotyrosine-modified epitopes as degrons for ubiquitination and proteasomal degradation, yet the molecular basis of substrate recognition has remained elusive. Here, we report co-crystal structures of SOCS2-ElonginB-ElonginC in complex with phosphorylated peptides from substrates growth hormone receptor (GHR-pY595) and erythropoietin receptor (EpoR-pY426) at 1.98 Å and 2.69 Å, respectively. Both peptides bind in an extended conformation recapitulating the canonical SH2 domain-pY pose, but capture different conformations of the EF loop via specific hydrophobic interactions. The flexible BG loop is fully defined in the electron density, and does not contact the substrate degron directly. Cancer-associated SNPs located around the pY pocket weaken substrate-binding affinity in biophysical assays. Our findings reveal insights into substrate recognition and specificity by SOCS2, and provide a blueprint for small molecule ligand design. The suppressor of cytokine signaling 2 (SOCS2) is a component of the Cullin5 E3 ubiquitin ligase complex. Here the authors provide insights into substrate recognition and specificity of SOCS2 by determining the crystal structures of the SOCS2-ElonginB-ElonginC in complex with phosphorylated peptides from two of its substrates the growth hormone receptor and erythropoietin receptor.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 631/45 / 631/45/535 / 631/45/535/1266 / 631/45/611 / 631/45/612 / Conformation / Crystal structure / Crystallography, X-Ray / Electron density / Epitopes / Erythropoietin / Growth hormones / Humanities and Social Sciences / Humans / Hydrophobicity / multidisciplinary / Peptides / Phosphotyrosine / Phosphotyrosine - chemistry / Polymorphism, Single Nucleotide / Proteasomes / Protein Conformation / Receptors, Erythropoietin - chemistry / Receptors, Somatotropin - chemistry / Recognition / Science / Science (multidisciplinary) / Sequence Alignment / Substrate Specificity / Substrates / Suppressor of Cytokine Signaling Proteins - chemistry / Suppressor of Cytokine Signaling Proteins - genetics / Ubiquitin / Ubiquitin-protein ligase / Ubiquitin-Protein Ligases - chemistry / Ubiquitination