SLAP2 Adaptor Binding Disrupts c-CBL Autoinhibition to Activate Ubiquitin Ligase Function

JOURNAL OF MOLECULAR BIOLOGY

卷:433

Article

Wybenga-Groot, Leanne E.^1,2,3  Tench, Andrea J.^1,2,4  Simpson, Craig D.^1,2  St Germain, Jonathan⁵  Raught, Brian^4,5  Moran, Michael F.^2,3,6  McGlade, C. Jane^1,2,4 

[1] Hosp Sick Children, Arthur & Sonia Labatt Brain Tumour Res Ctr, 555 Univ Ave, Toronto, ON M5G 1X8, Canada

[2] Hosp Sick Children, Program Cell Biol, 555 Univ Ave, Toronto, ON M5G 1X8, Canada

[3] Hosp Sick Children, SPARC BioCtr, 555 Univ Ave, Toronto, ON M5G 1X8, Canada

[4] Univ Toronto, Dept Med Biophys, 610 Univ Ave, Toronto, ON M5G 2M9, Canada

[5] Univ Hlth Network, Princess Margaret Canc Ctr, Toronto, ON M5G 1L7, Canada

[6] Dept Mol Genet, 1 Kings Coll Circle, Toronto, ON M5S 1A8, Canada

关键词: Src-like adaptor protein;    CBL;    protein-protein interaction;    ubiquitin ligase;    X-ray crystal structure;    activation mechanism;   

DOI  :  10.1016/j.jmb.2021.166880

来源: Elsevier

【 摘 要 】

D CBL is a RING type E3 ubiquitin ligase that functions as a negative regulator of tyrosine kinase signaling and loss of CBL E3 function is implicated in several forms of leukemia. The Src-like adaptor proteins (SLAP/SLAP2) bind to CBL and are required for CBL-dependent downregulation of antigen receptor, cytokine receptor, and receptor tyrosine kinase signaling. Despite the established role of SLAP/SLAP2 in regulating CBL activity, the nature of the interaction and the mechanisms involved are not known. To understand the molecular basis of the interaction between SLAP/SLAP2 and CBL, we solved the crystal structure of CBL tyrosine kinase binding domain (TKBD) in complex with SLAP2. The carboxy-terminal region of SLAP2 adopts an a-helical structure which binds in a cleft between the 4H, EF-hand, and SH2 domains of the TKBD. This SLAP2 binding site is remote from the canonical TKBD phosphotyrosine peptide binding site but overlaps with a region important for stabilizing CBL in its autoinhibited conformation. In addition, binding of SLAP2 to CBL in vitro activates the ubiquitin ligase function of autoinhibited CBL. Disruption of the CBL/SLAP2 interface through mutagenesis demonstrated a role for this protein-protein interaction in regulation of CBL E3 ligase activity in cells. Our results reveal that SLAP2 binding to a regulatory cleft of the TKBD provides an alternative mechanism for activation of CBL ubiquitin ligase function. (C) 2021 Elsevier Ltd. All rights reserved.

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