Tsg101 chaperone function revealed by HIV-1 assembly inhibitors

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• HIV-1 replication depends on Tsg101, a key component of the endosomal sorting complex required for transport (ESCRT) machinery.
• Tsg101's ubiquitin (Ub) E2 variant (UEV) domain has distinct pockets for binding PT/SAP motifs and Ub, crucial for viral assembly and budding.
• The precise role of Tsg101's Ub-binding function in HIV-1 production remains largely uncharacterized.

Purpose of the Study:

• To investigate the contribution of Tsg101's Ub-binding function to HIV-1 assembly and replication.
• To elucidate the mechanism by which drugs targeting Tsg101's Ub-binding pocket affect viral production.

Main Methods:

• Utilized commonly used drugs to disrupt Tsg101's Ub-binding pocket.
• Employed Nuclear Magnetic Resonance (NMR) spectroscopy to analyze drug-Tsg101 interactions.
• Assessed the impact of disrupted Ub-binding on HIV-1 assembly stages.

Main Results:

• Disruption of Tsg101's Ub-binding pocket by drugs arrested HIV-1 assembly at an early stage, distinct from PTAP-mediated binding disruption.
• NMR analysis confirmed that drugs form covalent adducts near the Ub-binding pocket, specifically inhibiting Ub binding, not PTAP binding.
• The findings indicate that Tsg101's Ub-binding capability is essential for an early step in viral assembly.

Conclusions:

• The Ub-binding pocket of Tsg101 plays a critical role in the initiation of HIV-1 budding, functioning as a chaperone.
• Targeting Tsg101's Ub-binding site represents a potential strategy for inhibiting HIV-1 replication.
• This study reveals a novel mechanism by which small molecules can interfere with essential viral processes.