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Updated: May 17, 2026

Measuring Endoplasmic Reticulum Stress and Unfolded Protein Response in HIV-1 Infected T-Cells and Analyzing its Role in HIV-1 Replication
Published on: June 14, 2024
Core-binding factor β increases the affinity between human Cullin 5 and HIV-1 Vif within an E3 ligase complex
Jason D Salter1, Geoffrey M Lippa, Ivan A Belashov
1Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States.
The HIV-1 Vif protein binds tightly to cellular proteins, including Cullin 5 (Cul5) and core-binding factor β (CBFβ), to degrade the antiviral APOBEC3G (A3G). This interaction is crucial for viral replication and offers potential therapeutic targets.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- HIV-1 Vif protein targets APOBEC3G (A3G) for degradation, a key step in viral replication.
- Vif acts as a receptor for the Elongin B/C/Cullin 5 (EloB/C/Cul5) E3 ubiquitin ligase complex.
- Unlike cellular receptors, Vif requires human core-binding factor β (CBFβ) for its function.
Purpose of the Study:
- To investigate the binding interactions between HIV-1 Vif, EloB/C/Cul5, and CBFβ.
- To elucidate the role of CBFβ in stabilizing Vif for Cul5 binding.
- To identify potential therapeutic targets for HIV-1 infection.
Main Methods:
- Isothermal titration calorimetry (ITC) to measure binding affinities.
- Thermodynamic analysis (heat capacity changes) to understand binding mechanisms.
- Biochemical assays to study protein-protein interactions.
Main Results:
- Cullin 5 (Cul5) binds significantly tighter to full-length Vif in the presence of CBFβ (K(d) = 5 ± 2 nM) compared to Vif lacking the CBFβ-binding region (K(d) = 327 ± 40 nM).
- CBFβ prestabilizes Vif, enhancing the interaction with Cul5, particularly involving Vif's C-terminal Zn(2+)-binding motif.
- Evidence suggests an additional binding interface between Cul5 and an N-terminal region of Vif.
Conclusions:
- CBFβ plays a critical role in enhancing the Vif-Cul5 interaction, essential for APOBEC3G degradation.
- The findings reveal a detailed mechanism of Vif function and highlight potential strategies for therapeutic intervention.
- Understanding these molecular interactions can inform the design of novel antiviral drugs targeting HIV-1 replication.
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