The C-Terminal Proline-Rich Tail of Human Immunodeficiency Virus Type 2 Vpx Is Necessary for Nuclear Localization of the Viral Preintegration Complex in Nondividing Cells

Abstract

Human immunodeficiency virus type 2 (HIV-2), like other lentiviruses, is capable of infecting nondividing T cells and macrophages. The present work shows that in HIV-2-infected cells, Vpx is necessary for efficient nuclear import of the preintegration complex. In agreement with this finding, the subcellular localization of a GFP-Vpx fusion protein was found to be predominantly nuclear. However, deletion of the proline-rich C-terminal 11 residues of Vpx resulted in a shift of the fusion protein to the cytoplasm. Furthermore, the same deletion in the context of the provirus resulted in a decrease in nuclear import of the preintegration complex and attenuated replication in macrophages.

Simian Immunodeficiency Virus Vpx Is Imported into the Nucleus via Importin Alpha-Dependent and -Independent Pathways

“…The recent reports from our and other laboratories have revealed that the C-terminal region contributes to the nuclear localization of Vpx (37,39). In the present investigation, for the first time, we show that two distinct noncanonical nuclear targeting signals reside within SIV Vpx and direct Vpx as well as other heterologous cytoplasmic proteins into the nucleus.…”

“…1C). Taken together, these results provide evidence for the presence of a functional NLS in the N-terminal domain (aa 20 to 40) of Vpx, in addition to the recently identified NLS in the C terminus of Vpx (37,39). Vpx with the N-terminal NLS (Vpx20-40) is sufficient to target a heterologous protein to the nucleus.…”

“…As the Vpx protein is incorporated into the virion (27,28,32), it becomes available during early replication events, immediately following entry of the new virion into a target cell even before de novo viral protein synthesis can start (10,21,32,37,38). Based on such late expression during virus production and early availability during initial infection, it has been proposed that Vpx is involved in the early stages of the viral life cycle, particularly in the efficient import of the viral genome into the nuclear compartment of nonproliferating target cells (10,32,37,39,40,42). Vpx was found to participate in the active translocation of the large (Stokes radius, 28 nm) viral preintegration complex (PIC) across the limiting nuclear pore (10).…”

“…Vpx was found to participate in the active translocation of the large (Stokes radius, 28 nm) viral preintegration complex (PIC) across the limiting nuclear pore (10). Although Vpx displays evident karyophilic properties, it does not contain a canonical nuclear localization signal (NLS) (32,37,39,40). The mechanism of Vpx-mediated nuclear import appears novel, but how Vpx cooperates with viral and host proteins to transport the viral PIC into the nucleus remains elusive.…”

HIV Genome-Wide Protein Associations: a Review of 30 Years of Research

“…In contrast to the HIV-1 Vpr-NC Gag interaction, SIV Vpx does not interact with NC Gag (314). In nondividing cells, the conserved domain of Vpx (positions 60 to 85) in HIV-2 and SIV is essential for PIC nuclear import (334,335). Regarding the interaction domains, the leucine-containing motif D 17 …”