title: Rhesus TRIM5α disrupts the HIV-1 capsid at the inter-hexamer interfaces.
abstract: TRIM proteins play important roles in the innate immune defense against retroviral infection, including human immunodeficiency virus type-1 (HIV-1). Rhesus macaque TRIM5α (TRIM5α(rh)) targets the HIV-1 capsid and blocks infection at an early post-entry stage, prior to reverse transcription. Studies have shown that binding of TRIM5α to the assembled capsid is essential for restriction and requires the coiled-coil and B30.2/SPRY domains, but the molecular mechanism of restriction is not fully understood. In this study, we investigated, by cryoEM combined with mutagenesis and chemical cross-linking, the direct interactions between HIV-1 capsid protein (CA) assemblies and purified TRIM5α(rh) containing coiled-coil and SPRY domains (CC-SPRY(rh)). Concentration-dependent binding of CC-SPRY(rh) to CA assemblies was observed, while under equivalent conditions the human protein did not bind. Importantly, CC-SPRY(rh), but not its human counterpart, disrupted CA tubes in a non-random fashion, releasing fragments of protofilaments consisting of CA hexamers without dissociation into monomers. Furthermore, such structural destruction was prevented by inter-hexamer crosslinking using P207C/T216C mutant CA with disulfide bonds at the CTD-CTD trimer interface of capsid assemblies, but not by intra-hexamer crosslinking via A14C/E45C at the NTD-NTD interface. The same disruption effect by TRIM5α(rh) on the inter-hexamer interfaces also occurred with purified intact HIV-1 cores. These results provide insights concerning how TRIM5α disrupts the virion core and demonstrate that structural damage of the viral capsid by TRIM5α is likely one of the important components of the mechanism of TRIM5α-mediated HIV-1 restriction.
authors: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America.
authors: Gongpu
authors: G
authors: Zhao
authors: Danxia
authors: D
authors: Ke
authors: Thomas
authors: T
authors: Vu
authors: Jinwoo
authors: J
authors: Ahn
authors: Vaibhav B
authors: VB
authors: Shah
authors: Ruifeng
authors: R
authors: Yang
authors: Christopher
authors: C
authors: Aiken
authors: Lisa M
authors: LM
authors: Charlton
authors: Angela M
authors: AM
authors: Gronenborn
authors: Peijun
authors: P
authors: Zhang
mesh_terms: D000818:Animals; D000090103:Antiviral Restriction Factors; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D015497:HIV-1 / Q000276:immunology / Q000378:metabolism / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D008253:Macaca mulatta; D026901:Membrane Transport Proteins / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases; D016335:Zinc Fingers
chemical_list: D000090103:Antiviral Restriction Factors; D036022:Capsid Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D011506:Proteins; D000070584:Tripartite Motif Proteins; C477346:TRIM5 protein, human; C482587:TRIM5(alpha) protein, rhesus monkey; D044767:Ubiquitin-Protein Ligases