Inhibition of HIV Budding by a Genetically Selected Cyclic Peptide Targeting the Gag−TSG101 Interaction

Abstract

The egress of HIV particles from virus-infected cells is accomplished by the recruitment of proteins that normally mediate host cell endocytic functions. This process requires interaction of the HIV Gag protein with the host protein TSG101 (tumor susceptibility gene 101). Here, we report the use of a bacterial reverse two-hybrid system to identify cyclic peptides that interfere with the Gag−TSG101 interaction and the finding that a five amino acid peptide discovered by this approach can disrupt the interaction and consequently inhibit HIV egress. The inhibiting molecule, which was selected from a cyclic peptide library containing ∼3.2 × 106 members, differs in primary sequence from the interacting sites of either TSG101 or Gag. Addition of cyclic peptide tagged with an HIV Tat sequence, which previously has been shown to enhance protein translocation across plasma membranes, to cultured human cells inhibited the production of virus-like particles (VLPs) by these cells (IC50 of 7 μM), and this inhibition occurred in the absence of adverse affects on normal endocytic functions mediated by TSG101. A mutant Gag protein not dependent on TSG101 for release was unaffected by the cyclic peptide. Our findings, which suggest that interference with the TSG101−Gag interaction by cyclic peptides may be of practical use in the treatment of HIV infections, identify a specific cyclic peptide that reduces VLP release by this mechanism; they also demonstrate that the efficiency of interference with protein−protein interactions by cyclic peptides can be enhanced by tagging the peptides with translocation-promoting sequences. Collectively our results support the notion that small molecule therapeutics that inhibit specific interactions between viral and host proteins may have general applicability in antiviral therapy.

The association of the cytoplasmic domains of interleukin 4 receptor alpha and interleukin 13 receptor alpha 2 regulates interleukin 4 signaling

“…and pAH69 26 as previously described 27,28 to give the IL-4Ra-IL13Ra2 RTHS. The IL-4Ra-IL-13Ra2 P366A RTHS was generated by site-directed mutagenesis (SDM), cloned into pTHCP14-IL-4Ra-IL-13Ra2 with AgeI and SacI.…”

Evolution of cyclic peptide protease inhibitors

“…Toward this end, a method to generate libraries of cyclic peptides that employs circularly permuted inteins which self-catalyze the cyclization of a target peptide has been developed in Escherichia coli (16)(17)(18)(19)(20)(21)(22). This method, termed split intein catalyzed ligation of proteins and peptides (SICLOPPS), has been previously used to select inhibitors of hydrolases, methyl transferases, and other proteins (17,20,(22)(23)(24). However, one major disadvantage of this system relative to nonribosomal peptide synthesis is the limited repertoire of functional groups that can be accessed.…”

Human genetic variation altering anthrax toxin sensitivity

“…Host variation has the potential to influence infectious disease outcome not only through genes that combat pathogens (15,16), but also through host genes that are needed for pathogen propagation (14,17) or the detrimental effects of microbial toxins (18). Among the pathogens and toxins that have been shown experimentally to exploit host genes are HIV, malaria, hepatitis, leprosy, and anthrax toxin (11)(12)(13)(19)(20)(21)(22).…”