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Determinants for the rhesus monkey TRIM5alpha-mediated block of the late phase of HIV-1 replication
Ryuta Sakuma1, Seiga Ohmine1, Yasuhiro Ikeda1
1From the Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota 55905.
Abstract:
Rhesus monkey TRIM5alpha (TRIM5alpharh) includes RING, B-box, coiled-coil, and B30.2(PRYSPRY) domains and blocks HIV-1 infection by targeting HIV-1 core through a B30.2(PRYSPRY) domain. Previously, we reported that TRIM5alpharh also blocks HIV-1 production in a B30.2(PRYSPRY)-independent manner. Efficient encapsidation of TRIM5alpharh, but not human TRIM5alpha (TRIM5alphahu), in HIV-1 virus-like particles suggests the interaction between Gag and TRIM5alpharh during viral assembly. Here, we determined responsible regions for late restriction activity of TRIM5alpharh. The RING disruption, but not the replacement with human TRIM21 RING, ablated the efficient encapsidation and the late restriction, suggesting that a RING structure was essential for the late restriction and efficient interaction with HIV-1 Gag. The prominent cytoplasmic body formation of TRIM5alpharh, which depended on the coiled-coil domain and the ensuing linker 2 region, was not required for the encapsidation. Intriguingly, TRIM5alpharh coiled-coil domain mutants (M133T and/or T146A) showed impaired late restriction activity, despite the efficient encapsidation and cytoplasmic body formation. Our results suggest that the TRIM5alpharh-mediated late restriction involves at least two distinct activities as follows: (i) interaction with HIV-1 Gag polyprotein through the N-terminal, RING, and B-box 2 regions of a TRIM5alpharh monomer, and (ii) an effector function(s) that depends upon the coiled-coil and linker 2 domains of TRIM5alpharh. We speculate that the TRIM5alpharh coiled-coil region recruits additional factor(s), such as other TRIM family proteins or a cellular protease, during the late restriction. RBCC domains of TRIM family proteins may play a role in sensing newly synthesized viral proteins as a part of innate immunity against viral infection.
Insights
Rhesus monkey TRIM5alpha (TRIM5alpharh) blocks HIV-1 production through distinct mechanisms. Its RING domain is crucial for interacting with HIV-1 Gag and restricting viral production, while coiled-coil domains mediate effector functions.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Rhesus monkey TRIM5alpha (TRIM5alpharh) is known to inhibit HIV-1 infection.
- TRIM5alpharh blocks HIV-1 infection via its B30.2(PRYSPRY) domain, and also inhibits HIV-1 production independently of this domain.
- Efficient encapsidation of TRIM5alpharh in HIV-1 virus-like particles suggests interaction with Gag during viral assembly.
Purpose of the Study:
- To identify the specific regions of TRIM5alpharh responsible for its late restriction activity against HIV-1 production.
- To elucidate the molecular mechanisms underlying TRIM5alpharh's interaction with HIV-1 Gag and its role in viral assembly and production.
Main Methods:
- Mutagenesis of TRIM5alpharh domains (RING, coiled-coil, linker 2) to assess their role in encapsidation and late restriction.
- Analysis of TRIM5alpharh encapsidation in HIV-1 virus-like particles.
- Evaluation of cytoplasmic body formation and late restriction activity of TRIM5alpharh mutants.
Main Results:
- Disruption of the RING domain abolished efficient encapsidation and late restriction, indicating its essential role in interacting with HIV-1 Gag.
- Cytoplasmic body formation, dependent on the coiled-coil and linker 2 domains, was not required for encapsidation.
- Mutations in the coiled-coil domain impaired late restriction activity, despite maintaining efficient encapsidation and cytoplasmic body formation.
Conclusions:
- TRIM5alpharh-mediated late restriction of HIV-1 production involves at least two distinct activities: Gag interaction via N-terminal, RING, and B-box 2 regions, and effector functions dependent on coiled-coil and linker 2 domains.
- The coiled-coil region may recruit additional factors for late restriction, highlighting a potential role in innate immunity.
- TRIM5alpharh's RBCC domains might sense viral proteins, contributing to innate antiviral defense.
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