Human Dlg protein binds to the envelope glycoproteins of human T-cell leukemia virus type 1 and regulates envelope mediated cell-cell fusion in T lymphocytes.
Human homologue of the Drosophila Dlg tumor suppressor (hDlg) is a widely expressed scaffold protein implicated in the organization of multi-protein complexes at cell adhesion sites such as the neuronal synapse. hDlg contains three PDZ domains that mediate its binding to the consensus motifs present at the C-termini of various cell surface proteins, thus inducing their clustering and/or stabilization at the plasma membrane. Using a yeast two-hybrid screen, we identified hDlg as a cellular binding partner of a viral membrane integral protein, the envelope glycoprotein (Env) of human T-cell leukemia virus type 1 (HTLV-1). HTLV-1 is a human retrovirus that infects CD4+ T lymphocytes and is preferentially transmitted via direct contacts between infected and target cells, through a structure referred to as the virological synapse. Here, we demonstrate that hDlg interacts with a classical PDZ domain-binding motif present at the C-terminus of the cytoplasmic domain of HTLV-1 Env and conserved in the related HTLV-2 virus. We further document that, in HTLV-1 infected primary T cells, hDlg and Env are concentrated in restricted areas of the plasma membrane, enriched in molecules involved in T-cell contacts. The presence of Gag proteins responsible for viral assembly and budding in these areas indicated that they constitute platforms for viral assembly and transmission. Finally, a mutant virus unable to bind hDlg exhibited a decreased ability to trigger Env mediated cell fusion between T lymphocytes. We thus propose that hDlg stabilizes HTLV-1 envelope glycoproteins at the virological synapse formed between infected and target cells, hence assisting the cell-to-cell transmission of the virus.
Département Biologie Cellulaire, CNRS UMR 8104 and INSERM U567, Institut Cochin, 22 rue Méchain, 75014 Paris, France. vblot@cochin.inserm.fr
Vincent
V
Blot
Lélia
L
Delamarre
Fabien
F
Perugi
Danielle
D
Pham
Serge
S
Bénichou
Richard
R
Benarous
Toshihiko
T
Hanada
Athar H
AH
Chishti
Marie-Christine
MC
Dokhélar
Claudine
C
Pique
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002448:Cell Adhesion; D002459:Cell Fusion; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D000074288:Discs Large Homolog 1 Protein; D015686:Gene Products, env / Q000378:metabolism; D015683:Gene Products, gag / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013601:T-Lymphocytes / Q000821:virology; D020798:Two-Hybrid System Techniques; D014760:Viral Fusion Proteins / Q000737:chemistry
D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D000074288:Discs Large Homolog 1 Protein; D015686:Gene Products, env; D015683:Gene Products, gag; D006023:Glycoproteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins; D005982:Glutathione Transferase