title: Inhibition of HIV-1 Maturation via Small-Molecule Targeting of the Amino-Terminal Domain in the Viral Capsid Protein.
abstract: The human immunodeficiency virus type 1 (HIV-1) capsid protein is an attractive therapeutic target, owing to its multifunctionality in virus replication and the high fitness cost of amino acid substitutions in capsids to HIV-1 infectivity. To date, small-molecule inhibitors have been identified that inhibit HIV-1 capsid assembly and/or impair its function in target cells. Here, we describe the mechanism of action of the previously reported capsid-targeting HIV-1 inhibitor, Boehringer-Ingelheim compound 1 (C1). We show that C1 acts during HIV-1 maturation to prevent assembly of a mature viral capsid. However, unlike the maturation inhibitor bevirimat, C1 did not significantly affect the kinetics or fidelity of Gag processing. HIV-1 particles produced in the presence of C1 contained unstable capsids that lacked associated electron density and exhibited impairments in early postentry stages of infection, most notably reverse transcription. C1 inhibited assembly of recombinant HIV-1 CAin vitroand induced aberrant cross-links in mutant HIV-1 particles capable of spontaneous intersubunit disulfide bonds at the interhexamer interface in the capsid lattice. Resistance to C1 was conferred by a single amino acid substitution within the compound-binding site in the N-terminal domain of the CA protein. Our results demonstrate that the binding site for C1 represents a new pharmacological vulnerability in the capsid assembly stage of the HIV-1 life cycle.IMPORTANCEThe HIV-1 capsid protein is an attractive but unexploited target for clinical drug development. Prior studies have identified HIV-1 capsid-targeting compounds that display different mechanisms of action, which in part reflects the requirement for capsid function at both the efferent and afferent phases of viral replication. Here, we show that one such compound, compound 1, interferes with assembly of the conical viral capsid during virion maturation and results in perturbations at a specific protein-protein interface in the capsid lattice. We also identify and characterize a mutation in the capsid protein that confers resistance to the inhibitor. This study reveals a novel mechanism by which a capsid-targeting small molecule can inhibit HIV-1 replication.
authors.affiliation: Dana-Farber Cancer Institute, Department of Cancer Immunology and Virology, Boston, Massachusetts, USA.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Upul D
authors.initials: UD
authors.lastname: Halambage
authors.affiliation: Dana-Farber Cancer Institute, Department of Cancer Immunology and Virology, Boston, Massachusetts, USA.
authors.forename: Kellie A
authors.initials: KA
authors.lastname: Jurado
authors.affiliation: Dana-Farber Cancer Institute, Department of Cancer Immunology and Virology, Boston, Massachusetts, USA.
authors.forename: Augusta V
authors.initials: AV
authors.lastname: Jamin
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Dana-Farber Cancer Institute, Department of Cancer Immunology and Virology, Boston, Massachusetts, USA alan_engelman@dfci.harvard.edu chris.aiken@vanderbilt.edu.
authors.forename: Alan N
authors.initials: AN
authors.lastname: Engelman
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA alan_engelman@dfci.harvard.edu chris.aiken@vanderbilt.edu.
authors.forename: Christopher
authors.initials: C
authors.lastname: Aiken
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D019380:Anti-HIV Agents / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D001665:Binding Sites / Q000235:genetics; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D024882:Drug Resistance, Viral / Q000235:genetics; D057809:HEK293 Cells; D015497:HIV-1 / Q000235:genetics / Q000254:growth & development*; D006801:Humans; D017434:Protein Structure, Tertiary; D048348:Reverse Transcription / Q000187:drug effects; D019065:Virus Assembly / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents; D001562:Benzimidazoles; D036022:Capsid Proteins
keywords: HIV-1; capsid; inhibitor; maturation