Structural basis for HIV-1 REV nucleocytoplasmic trafficking

The National Institute of Allergy and Infectious Diseases awarded the University of Alabama at Birmingham $172,220 on November 3, 2025, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to support structural and mechanistic research into HIV-1 Rev nucleocytoplasmic trafficking as a potential target for novel antiretroviral drug development.

The research investigates how the HIV-1 Rev protein, which mediates nuclear export of viral messenger RNA necessary for virus assembly, is recognized and transported through the nuclear pore complex by human host machinery. The work addresses the clinical need for new antiretrovirals, as people living with HIV on current combination antiretroviral therapies face lifetime treatment requirements and increasing risk of drug-resistant viral strains.

The project employs two complementary aims. Aim 1 uses cryogenic-electron microscopy, pull-down assays, and turbidity assays to visualize and characterize the structural binding determinants between HIV-1 Rev and the host importin-B protein. Aim 2 applies cryo-EM to explore mechanisms of CRM1-mediated nuclear export of Rev alone and Rev bound to the HIV-1 genome. The hypothesis underlying both aims posits that Rev hijacks human importin and exportin machinery—specifically importin-B and CRM1—to traffic through the nuclear pore complex while preventing Rev aggregation and non-specific RNA binding.

Work is performed in Birmingham, Alabama. The award runs through June 30, 2028.

Abstract

Human immunodeficiency virus 1 (HIV-1) targets the human immune system and can lead to the development of acquired immunodeficiency syndrome (aids), increasing susceptibility to opportunistic infections and tumors. Current HIV-1/aids treatments involve the utilization of combination antiretroviral therapies (cart) that target and inhibit multiple steps of the HIV-1 replication cycle. People living with HIV must stay on treatment for the rest of their lives, which increases the risk of HIV-1 developing resistance to antiretrovirals. As a result, there is a need for the development of novel antiretrovirals. One target for possible antiretroviral treatment is the HIV-1 protein called REV (regulator of expression of virion proteins). REV functions as a nucleocytoplasmic shuttling protein for the nuclear export of viral mrna necessary for virus assembly. To properly mediate the export of this mrna, REV must be able to translocate back and forth through the nuclear pore complex (NPC). REV contains a nuclear localization signal and a nuclear export signal able to bind host importins and exportins, which are responsible for host cargo nucleocytoplasmic trafficking. This F31 proposal seeks to decipher how HIV-1 REV is recognized, bound, and trafficked through the NPC by the host nuclear transport machinery. We hypothesize that REV hijacks human importins and exportins, specifically importin-β and CRM1 (or exportin), for trafficking REV through the NPC and preventing REV aggregation and non-specific RNA binding. Aim 1 of this proposal explores binding determinants between HIV-1 REV and importin-β. We will utilize cryogenic-electron microscopy (cryo-EM) and pull-down and turbidity assays to visualize and characterize the importin-β:REV structure. Aim 2 explores the mechanisms of CRM1 nuclear export of REV alone and bound to the HIV-1 genome. To better understand these mechanisms, we will use cryo-EM to determine the structures of CRM1 bound to REV before and after adding viral mrna.