TRIM5α Restriction of HIV-1-N74D Viruses in Lymphocytes Is Caused by a Loss of Cyclophilin A Protection.

Anastasia Selyutina,Felipe Diaz-Griffero,Lacy M Simons,Karen A Kirby,Judd F Hultquist,Angel Bulnes-Ramos,Pan Hu,Stefan G Sarafianos

doi:10.3390/v14020363

Abstract

The core of HIV-1 viruses bearing the capsid change N74D (HIV-1-N74D) do not bind the human protein CPSF6. In primary human CD4+ T cells, HIV-1-N74D viruses exhibit an infectivity defect when compared to wild-type. We first investigated whether loss of CPSF6 binding accounts for the loss of infectivity. Depletion of CPSF6 in human CD4+ T cells did not affect the early stages of wild-type HIV-1 replication, suggesting that defective infectivity in the case of HIV-1-N74D viruses is not due to the loss of CPSF6 binding. Based on our previous result that cyclophilin A (Cyp A) protected HIV-1 from human tripartite motif-containing protein 5α (TRIM5αhu) restriction in CD4+ T cells, we found that depletion of TRIM5αhu in CD4+ T cells rescued the infectivity of HIV-1-N74D, suggesting that HIV-1-N74D cores interacted with TRIM5αhu. Accordingly, TRIM5αhu binding to HIV-1-N74D cores was increased compared with that of wild-type cores, and consistently, HIV-1-N74D cores lost their ability to bind Cyp A. In agreement with the notion that N74D capsids are defective in their ability to bind Cyp A, we found that HIV-1-N74D viruses were 20-fold less sensitive to TRIMCyp restriction when compared to wild-type viruses in OMK cells. Structural analysis revealed that N74D hexameric capsid protein in complex with PF74 is different from wild-type hexameric capsid protein in complex with PF74, which explains the defect of N74D capsids to interact with Cyp A. In conclusion, we showed that the decreased infectivity of HIV-1-N74D in CD4+ T cells is due to a loss of Cyp A protection from TRIM5αhu restriction activity.

Highlights

Introduction published maps and institutional affilHuman cleavage and polyadenylation specificity factor subunit 6 (CPSF6) is a nuclear protein that belongs to the serine/arginine-rich protein family
human immunodeficiency virus-1 (HIV-1)-N74D-green fluorescent protein (GFP) viruses showed a defect on infectivity when compared to wild-type viruses when infecting the lung human cell line A549 or the Jurkat T cell line (Figure 1)
Our results indicate that HIV-1-N74D viruses do not interact with cyclophilin A (Cyp A) biochemically; we hypothesized that HIV-1-N74D viruses should be less sensitive to the restriction factor TRIMCyp when compared to wild-type viruses

Summary

Introduction

Human cleavage and polyadenylation specificity factor subunit 6 (CPSF6) is a nuclear protein that belongs to the serine/arginine-rich protein family. Expression of a cytosolic fragment of CPSF6 [CPSF6(1–358)] was found to potently block human immunodeficiency virus-1 (HIV-1) infection before the formation of 2-long terminal repeat circles [1], and this inhibition of HIV-1 infection correlated with the ability of CPSF6(1–358) to bind to the capsid and prevent uncoating [2–4]. The serial passaging of HIV-1 in human cells overexpressing. CPSF6(1–358) resulted in the generation of escape-mutant viruses bearing the N74D capsid change (HIV-1-N74D) [1], and binding studies of HIV-1 capsids with N74D mutations to CPSF6(1–358) demonstrated a lack of binding as the mechanism for escape [1,5]. HIV-1N74D viruses have decreased infectivity in Jurkat T cells when compared to wild-type, and recent studies showed that TRIM34 is important for this phenotype [6]. The overexpression of full-length CPSF6 remained nuclear and did not block HIV-1 infection, iations

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Conclusion