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Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
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Dynamic molecular architecture and substrate recruitment of cullin3-RING E3 ligase CRL3KBTBD2

Yuxia Hu1, Zhao Zhang2,3, Qiyu Mao1

  • 1Shanghai Fifth People's Hospital, Shanghai Institute of Infectious Disease and Biosecurity, Shanghai Key Laboratory of Medical Epigenetics and Institutes of Biomedical Sciences, Fudan University, Shanghai, China.

Nature Structural & Molecular Biology
|February 9, 2024
PubMed

Insights

The study reveals how the KBTBD2-CRL3 ubiquitin ligase complex degrades the p85α subunit, crucial for insulin signaling and preventing diseases like diabetes and cancer.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cellular Signaling

Background:

  • Phosphatidylinositol 3-kinase α (PI3Kα) is vital for insulin and IGF signaling, and its dysregulation contributes to oncogenesis.
  • Cellular p85α subunit levels are controlled by proteasomal degradation; impaired ubiquitination leads to diseases like diabetes and dwarfism.

Purpose of the Study:

  • To elucidate the structural mechanisms of ubiquitin ligase complexes that regulate p85α availability.
  • To understand the molecular basis of PI3Kα pathway dysregulation in metabolic and growth disorders.

Main Methods:

  • Structural elucidation of key ubiquitin ligase complexes.
  • Biochemical assays to determine substrate recruitment and complex assembly/disassembly dynamics.
  • Analysis of neddylation and deactivation mechanisms.

Main Results:

  • Identified KBTBD2 as the substrate receptor recruiting p85α to the CRL3 E3 ubiquitin ligase.
  • Demonstrated that CRL3KBTBD2 undergoes conformational changes upon substrate binding and neddylation, facilitating p85α ubiquitination.
  • Revealed the roles of NEDD8, COP9 signalosome, and CAND1 in regulating CRL3KBTBD2 activity and p85α degradation.

Conclusions:

  • The structural insights into p85α regulation by CRL3KBTBD2 provide a molecular basis for understanding diseases linked to PI3Kα pathway dysfunction.
  • This knowledge may pave the way for therapeutic strategies targeting glucose regulation, growth, and cancer.

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