Gyrase B Inhibitor Impairs HIV-1 Replication by Targeting Hsp90 and the Capsid Protein

Abstract

Chemical genetics is an emerging approach to investigate the biology of host-pathogen interactions. We screened several inhibitors of ATP-dependent DNA motors and detected the gyrase B inhibitor coumermycin A1 (C-A1) as a potent antiretroviral. C-A1 inhibited HIV-1 integration and gene expression from acutely infected cell, but the two activities mapped to distinct targets. Target discovery identified Hsp90 as the C-A1 target affecting viral gene expression. Chromatin immunoprecipitation revealed that Hsp90 associates with the viral promoter and may directly regulate gene expression. Molecular docking suggested that C-A1 binds to two novel pockets at the C terminal domain of Hsp90. C-A1 inhibited Hsp90 dimer formation, suggesting that it impairs viral gene expression by preventing Hsp90 dimerization at the C terminus. The inhibition of HIV-1 integration imposed by C-A1 was independent of Hsp90 and mapped to the capsid protein, and a point mutation at residue 105 made the virus resistant to this block. HIV-1 susceptibility to the integration block mediated by C-A1 was influenced by cyclophilin A. Our chemical genetic approach revealed an unexpected function of capsid in HIV-1 integration and provided evidence for a role of Hsp90 in regulating gene expression in mammalian cells. Both activities were amenable to inhibition by small molecules and represent novel antiretroviral drug targets.

Heat shock protein 90 controls HIV-1 reactivation from latency

“…We reported previously that Hsp90 associates with the HIV-1 promoter at chromatin and that hyperthermia increases the frequency of localization of Hsp90 at the viral transcriptional site (14,15). The integrated HIV-1 provirus may be considered as a cellular gene that needs to be rapidly activated.…”

“…We have previously shown that Hsp90 is required for HIV-1 gene expression (14,15). Others have shown that the NF-κB pathway is an important regulator of HIV-1 latency reactivation (12) and that Hsp90 and Cdc37 bind to the IKK complex (35).…”

“…HIV-1 latency is a multifactorial process involving chromatin modifications, low levels of specific transcription factors, integration site selection, and cell activation (11)(12)(13). We have discovered that the heat shock protein 90 (Hsp90) is required for HIV-1 gene expression and that it localizes at the viral promoter DNA (14). Furthermore, we reported that Hsp90 is required for enhanced HIV-1 replication in conditions of hyperthermia (fever) by stimulating transcriptional activity of the viral promoter (15).…”

Enhanced Autointegration in Hyperstable Simian Immunodeficiency Virus Capsid Mutants Blocked after Reverse Transcription

“…Changes in retroviral capsids can influence uncoating, reverse transcription, nuclear entry, chromatin targeting and binding, and integration (3,4,6,7,13,14,16,18,37). Here we describe two SIVmac239 capsid mutants, A87E and A87D, that uncoat less efficiently than wild-type SIVmac239 yet are capable of reverse transcription and nuclear entry.…”

“…Less expectedly, alterations in the capsid protein can affect subsequent steps in the early phase of lentivirus infection. An appreciation of the contribution of the capsid to multiple steps in the lentiviral life cycle has made capsid an attractive target of therapeutic intervention (6,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”