title: The V86M mutation in HIV-1 capsid confers resistance to TRIM5α by abrogation of cyclophilin A-dependent restriction and enhancement of viral nuclear import.
abstract: BACKGROUND
  HIV-1 is inhibited early after entry into cells expressing some simian orthologues of the tripartite motif protein family member TRIM5α. Mutants of the human orthologue (TRIM5αhu) can also provide protection against HIV-1. The host protein cyclophilin A (CypA) binds incoming HIV-1 capsid (CA) proteins and enhances early stages of HIV-1 replication by unknown mechanisms. On the other hand, the CA-CypA interaction is known to increase HIV-1 susceptibility to restriction by TRIM5α. Previously, the mutation V86M in the CypA-binding loop of HIV-1 CA was found to be selected upon serial passaging of HIV-1 in cells expressing Rhesus macaque TRIM5α (TRIM5αrh). The objectives of this study were (i) to analyze whether V86M CA allows HIV-1 to escape mutants of TRIM5αhu, and (ii) to characterize the role of CypA in the resistance to TRIM5α conferred by V86M.
  
  
  RESULTS
  We find that in single-cycle HIV-1 vector transduction experiments, V86M confers partial resistance against R332G-R335G TRIM5αhu and other TRIM5αhu variable 1 region mutants previously isolated in mutagenic screens. However, V86M HIV-1 does not seem to be resistant to R332G-R335G TRIM5αhu in a spreading infection context. Strikingly, restriction of V86M HIV-1 vectors by TRIM5αhu mutants is mostly insensitive to the presence of CypA in infected cells. NMR experiments reveal that V86M alters CypA interactions with, and isomerisation of CA. On the other hand, V86M does not affect the CypA-mediated enhancement of HIV-1 replication in permissive human cells. Finally, qPCR experiments show that V86M increases HIV-1 transport to the nucleus of cells expressing restrictive TRIM5α.
  
  
  CONCLUSIONS
  Our study shows that V86M de-couples the two functions associated with CA-CypA binding, i.e. the enhancement of restriction by TRIM5α and the enhancement of HIV-1 replication in permissive human cells. V86M enhances the early stages of HIV-1 replication in restrictive cells by improving nuclear import. In summary, our data suggest that HIV-1 escapes restriction by TRIM5α through the selective disruption of CypA-dependent, TRIM5α-mediated inhibition of nuclear import. However, V86M does not seem to relieve restriction of a spreading HIV-1 infection by TRIM5αhu mutants, underscoring context-specific restriction mechanisms.
authors: Department of Medical Biology, Laboratory of retrovirology and GROEM, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC G9A 5H7, Canada.
authors: Maxime
authors: M
authors: Veillette
authors: Katsiaryna
authors: K
authors: Bichel
authors: Paulina
authors: P
authors: Pawlica
authors: Stefan M V
authors: SM
authors: Freund
authors: Mélodie B
authors: MB
authors: Plourde
authors: Quang Toan
authors: QT
authors: Pham
authors: Carlos
authors: C
authors: Reyes-Moreno
authors: Leo C
authors: LC
authors: James
authors: Lionel
authors: L
authors: Berthoux
mesh_terms: D021581:Active Transport, Cell Nucleus; D000090103:Antiviral Restriction Factors; D002352:Carrier Proteins / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D021984:Cyclophilin A / Q000276:immunology* / Q000378:metabolism; D016655:HIV Core Protein p24 / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases
chemical_list: D000090103:Antiviral Restriction Factors; D002352:Carrier Proteins; D016655:HIV Core Protein p24; D050505:Mutant Proteins; D000070584:Tripartite Motif Proteins; C477346:TRIM5 protein, human; D044767:Ubiquitin-Protein Ligases; D021984:Cyclophilin A