Human immunodeficiency virus type 1 nucleocapsid p1 confers ESCRT pathway dependence

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Human immunodeficiency virus type 1 (HIV-1) utilizes the Endosomal Sorting Complex Required for Transport (ESCRT) pathway for progeny virion release.
• The C-terminal p6 domain of HIV-1 Gag contains late assembly (L) domains that interact with ESCRT components like Tsg101 and ALIX.
• Certain HIV-1 Gag constructs lacking the nucleocapsid (NC) domain show dispensability of L domains for particle production.

Purpose of the Study:

• To investigate the role of different regions of the HIV-1 Gag protein in ESCRT pathway dependence during viral budding.
• To determine which domains of Gag are essential for mediating sensitivity to ESCRT pathway inhibitors.

Main Methods:

• Construction and analysis of modified HIV-1 Gag constructs with domain substitutions (e.g., leucine zipper for NC).
• Assessment of viral particle production in the presence of dominant-negative ESCRT pathway inhibitors.
• Evaluation of L domain dependence in engineered Gag constructs.

Main Results:

• An L domain-independent Gag construct (Z(WT)) lacking NC-p1-p6 was resistant to ESCRT inhibitors.
• Restoring NC-p1-p6 to Z(WT) rendered it L domain-dependent and sensitive to ESCRT inhibition.
• Replacing the NC domain with a leucine zipper conferred ESCRT pathway sensitivity to the p1-p6 region, not p6 alone.
• In authentic HIV-1 Gag, deleting part of the NC domain and p1 alleviated inhibitor effects.

Conclusions:

• The ESCRT pathway dependence of HIV-1 budding is significantly influenced by the NC-p1 region of the Gag protein.
• The NC-p1 region, rather than p6 alone, plays a key role in mediating HIV-1's interaction with the ESCRT machinery.
• These findings provide insights into the mechanisms governing HIV-1 virion release and potential therapeutic targets.