title: The Transmembrane Domain of HIV-1 gp41 Inhibits T-Cell Activation by Targeting Multiple T-Cell Receptor Complex Components through Its GxxxG Motif.
abstract: To successfully infect and persist within its host, HIV-1 utilizes several immunosuppressive motifs within its gp41 envelope glycoprotein to manipulate and evade the immune system. The transmembrane domain (TMD) of gp41 downregulates T-cell receptor (TCR) signaling through a hitherto unknown mechanism. Interactions between TMDs within the membrane milieu have been shown to be typically mediated by particular amino acids, such as interactions between basic and acidic residues and dimerization motifs as GxxxG. The HIV-1 TMD exhibits both a polar arginine (Arg(696)) residue and a GxxxG motif, making them ideal candidates for mediators of TMD-TCR interaction. Using a primary T-cell activation assay and biochemical and biophysical methods, we demonstrate that the gp41 TMD directly interacts with TMDs of the TCR and the CD3 coreceptors (δ, γ, and ε) within the membrane, presumably leading to impairment of complex assembly. Additionally, we reveal that although Arg(696) does not affect TMD immunosuppression, the GxxxG motif is crucial in mediating gp41's TMD interaction with the CD3 coreceptors of the TCR. These findings suggest that compared with other gp41 immunosuppressive motifs, the gp41 TMD has multiple targets within the TCR complex, suggesting less susceptibility to evolutionary pressure and consequently being advantageous for the virus over the host immune response. Furthermore, as the GxxxG motif mediates interactions of the gp41 TMD with multiple receptors, it emerges as an attractive drug target. This multitarget inhibitory mechanism might be a strategy utilized by HIV to interfere with the function of additional host receptors.
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Etai
authors.initials: E
authors.lastname: Rotem
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Eliran Moshe
authors.initials: EM
authors.lastname: Reuven
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Yoel A
authors.initials: YA
authors.lastname: Klug
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Yechiel
authors.initials: Y
authors.lastname: Shai
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001120:Arginine / Q000737:chemistry; D017252:CD3 Complex / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D019281:Dimerization; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000378:metabolism*; D015497:HIV-1 / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D057131:Immune Evasion; D059425:Interferon-gamma Release Tests; D008213:Lymphocyte Activation; D008810:Mice, Inbred C57BL; D009154:Mutation; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D053835:Unilamellar Liposomes
chemical_list: D017252:CD3 Complex; C115335:CD3E protein, human; D015700:HIV Envelope Protein gp41; D010446:Peptide Fragments; D016692:Receptors, Antigen, T-Cell, gamma-delta; D053835:Unilamellar Liposomes; C514787:gp41 protein, Human immunodeficiency virus 1; D001120:Arginine