Primate Lentiviral Vpx Commandeers DDB1 to Counteract a Macrophage Restriction

Natalia Sharova,Yuanfei Wu,Mark Sharkey,Ruzena Stranska,Mario Stevenson,Xiaonan Zhu,Rajnish Kaushik,Michael H Malim

doi:10.1371/journal.ppat.1000057

Natalia Sharova, Yuanfei Wu + Show 6 more

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https://doi.org/10.1371/journal.ppat.1000057

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Journal: PLoS Pathogens	Publication Date: May 2, 2008
Citations: 209	License type: CC BY 4.0

Affiliation: University of Massachusetts Chan Medical School

Abstract

Primate lentiviruses encode four “accessory proteins” including Vif, Vpu, Nef, and Vpr/Vpx. Vif and Vpu counteract the antiviral effects of cellular restrictions to early and late steps in the viral replication cycle. We present evidence that the Vpx proteins of HIV-2/SIVSM promote virus infection by antagonizing an antiviral restriction in macrophages. Fusion of macrophages in which Vpx was essential for virus infection, with COS cells in which Vpx was dispensable for virus infection, generated heterokaryons that supported infection by wild-type SIV but not Vpx-deleted SIV. The restriction potently antagonized infection of macrophages by HIV-1, and expression of Vpx in macrophages in trans overcame the restriction to HIV-1 and SIV infection. Vpx was ubiquitylated and both ubiquitylation and the proteasome regulated the activity of Vpx. The ability of Vpx to counteract the restriction to HIV-1 and SIV infection was dependent upon the HIV-1 Vpr interacting protein, damaged DNA binding protein 1 (DDB1), and DDB1 partially substituted for Vpx when fused to Vpr. Our results indicate that macrophage harbor a potent antiviral restriction and that primate lentiviruses have evolved Vpx to counteract this restriction.

Highlights

The genomes of primate and non-primate lentiviruses encode ‘‘accessory’’ proteins from short open reading frames which are absent from the genomes of simple retroviruses [1]
In order to understand the functions of the viral protein R (Vpr)/viral protein X (Vpx) proteins in macrophage infection, we have focused on Vpx because of its profound impact on macrophage infection
We previously demonstrated that Vpx of HIV-2/SIVSM was essential for early events in macrophage infection yet dispensable for infection of CD4 lymphocytes [4]

Summary

Introduction

The genomes of primate and non-primate lentiviruses encode ‘‘accessory’’ proteins from short open reading frames which are absent from the genomes of simple retroviruses [1]. Members of the HIV-2/SIVSM/SIVMAC lineage contain an additional gene in this region termed viral protein X (Vpx) which was originally derived from the African green monkey vpr gene by an ancestral recombination event [4] Both Vpr and Vpx proteins are packaged into virions through association with the Gag polyprotein [5,6,7] and this points to an early role for these proteins in the virus life cycle (i.e., at a point proceeding de novo production of viral proteins). Vpx is essential for infection of simian macrophages by SIV in vitro and following infection of simian macrophages by Vpx minus SIVSM, late cDNA product are reduced while 2-LTR cDNAs, which are formed only after completion of reverse transcription, are absent [4,18] Whether any of these activities relate to the functional role of Vpr/Vpx proteins in primate lentivirus replication, is unclear. Its effect can be studied independently of other Vpr/Vpx-assigned activities including UDG association and cell cycle arrest

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