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Title: Inhibition of SCF ubiquitin ligases by engineered ubiquitin variants that target the Cul1 binding site on the Skp1–F-box interface

Skp1–Cul1–F-box (SCF) E3 ligases play key roles in multiple cellular processes through ubiquitination and subsequent degradation of substrate proteins. Although Skp1 and Cul1 are invariant components of all SCF complexes, the 69 different human F-box proteins are variable substrate binding modules that determine specificity. SCF E3 ligases are activated in many cancers and inhibitors could have therapeutic potential. Here, we used phage display to develop specific ubiquitin-based inhibitors against two F-box proteins, Fbw7 and Fbw11. Unexpectedly, the ubiquitin variants bind at the interface of Skp1 and F-box proteins and inhibit ligase activity by preventing Cul1 binding to the same surface. Using structure-based design and phage display, we modified the initial inhibitors to generate broad-spectrum inhibitors that targeted many SCF ligases, or conversely, a highly specific inhibitor that discriminated between even the close homologs Fbw11 and Fbw1. We propose that most F-box proteins can be targeted by this approach for basic research and for potential cancer therapies.
 [1] ;  [2] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [1] ;  [5] ;  [1]
  1. Univ. of Toronto, ON (Canada). Terrence Donnelly Center for Cellular and Biomolecular Research. Banting and Best Dept. of Medical Research. Dept. of Molecular Genetics
  2. Mount Sinai Hospital, Toronto, ON (Canada). Lunenfeld-Tanenbaum Research Inst.
  3. Cornell Univ., Argonne, IL (United States). Dept. of Chemistry and Chemical Biology
  4. Mount Sinai Hospital, Toronto, ON (Canada). Lunenfeld-Tanenbaum Research Inst.; Univ. of Montreal, QC (Canada). Inst. of Immunology and Cancer Research
  5. Mount Sinai Hospital, Toronto, ON (Canada). Lunenfeld-Tanenbaum Research Inst.; Univ. of Toronto, ON (Canada). Dept. of Molecular Genetics
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-06CH11357; GM103403; MOP-136956; MOP-126129
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 13; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Univ. of Toronto, ON (Canada)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Inst. of Health (NIH) (United States); Canadian Inst. of Health Research (CIHR) (Canada); Canadian Cancer Society Research Inst. (Canada)
Contributing Orgs:
Mount Sinai Hospital, Toronto, ON (Canada); Cornell Univ., Argonne, IL (United States); Univ. of Montreal, QC (Canada)
Country of Publication:
United States
60 APPLIED LIFE SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; Cul1 affinity; SCF inhibitors; Fbxw7; Fbxw11; β-Trcp