Selective Targeting of Virus Replication by Proton Pump Inhibitors

Abstract

Two proton pump inhibitors, tenatoprazole and esomeprazole, were previously shown to inhibit HIV-1 egress by blocking the interaction between Tsg101, a member of the ESCRT-I complex, and ubiquitin.Here, we deepen our understanding of prazole budding inhibition by studying a range of viruses in the presence of tenatoprazole. furthermore, we investigate the relationship between the chemistry of prodrug activation and HIV-1 inhibition for diverse prazoles currently on the market. We report that tenatoprazole is capable of inhibiting the replication of members of the enveloped filo, alpha, and herpes virus families but not the flavivirus group and not the non-enveloped poliovirus. Another key finding is that prazole prodrugs must be activated inside the cell, while their rate of activation in vitro correlated to their efficacy in cells. Our study lays the groundwork for future efforts to repurpose prazole-based compounds as antivirals that are both broad-spectrum and selective in nature.

RNA Binding Suppresses Tsg101 Recognition of Ub-Modified Gag and Facilitates Recruitment to the Plasma Membrane

“…The fact that (i), RNA is involved in the NC-Alix interface [1,39,40]; (ii), in the presence of RNA, Tsg101 is pulled-down with NC from cell lysates and in vitro [11,17] and (iii), small molecules that resemble nucleosides can bind the Tsg101 UEV domain [32,33] collectively suggested that Tsg101 might interact with RNA directly. To test this notion, we determined whether the UEV domain of Tsg101 recognized nucleic acid.…”

“…As interactions with tRNA constitute the most frequent binding event between cytosolic Gag and RNA [41], a commercial mixture of yeast tRNA was tested. Using NMR spectroscopy, we mapped a tRNA binding site to a recombinant Tsg101 UEV protein on the face opposite to that containing the mono-Ub-, P(T/S)AP-and prazole-binding pockets [32,33,42]; Figure 1). Attempts using RNA Bind-n-Seq (RBNS) [43] to determine if UEV recognition was based on a specific subset of tRNA and to obtain a quantitative assessment of the binding provided no evidence for sequence-specific binding (Haque, Hogg, Strickland, and Tjandra, unpublished observations).…”

“…Finding that the UEV recognized specific sequence and fold properties in the tRNA mixture that were not recognized in Ub makes it less likely that the RNA bound the UEV adventitiously. To determine whether binding tRNA might interfere with Ub binding, we took advantage of the fact that small molecules in the prazole family (Figure 3, panel A) target the β-hairpin site [32,33],…”

“…The identification of ZnF 2 as the element critical for Tsg101 recognition, as noted above, was made using lysates from cells co-transfected with non-coding HIV-1 gRNA and GST-tagged NCp15 [17]. These observations, combined with the fact that small molecules capable of binding the Tsg101 UEV domain resemble adenine or guanine [32,33], prompted us to investigate the possibility that the UEV domain might recognize RNA. Here, we identify tRNA as a new Tsg101 binding partner that influences Tsg101 recruitment in conjunction with Ub-binding and P(T/S)AP motif recognition.…”

Ilaprazole and other novel prazole-based compounds that bind Tsg101 inhibit viral budding of HSV-1/2 and HIV from cells

“…Tenatoprazole and esomeprazole were shown to quantitatively inhibit the release of infectious HIV-1 from 293T cells in culture, and it was suggested that these effects may be mediated via changes in viral interaction with Tsg101, a key component of the cellular ESCRT complex (5,33). Given multiple reports suggesting that herpes viruses also use cellular ESCRT proteins in their replication process (20)(21)(22)(23) we tested if the Tsg101-binding prazole drugs, which blocked budding of HIV-1, would also block the release of herpes viruses from cells.…”