title: A natural variability in the proline-rich motif of Nef modulates HIV-1 replication in primary T cells.
abstract: In the infected host, the Nef protein of HIV/SIV is required for high viral loads and thus disease progression. Recent evidence indicates that Nef enhances replication in the T cell compartment after the virus is transmitted from dendritic cells (DC). The underlying mechanism, however, is not clear. Here, we report that a natural variability in the proline-rich motif (R71T) profoundly modulated Nef-stimulated viral replication in primary T cells of immature dendritic cell/T cell cocultures. Whereas both Nef variants (R/T-Nef) downregulated CD4, only the isoform supporting viral replication (R-Nef) efficiently interacted with signaling molecules of the T cell receptor (TCR) environment and stimulated cellular activation. Structural analysis suggested that the R to T conversion induces conformational changes, altering the flexibility of the loop containing the PxxP motif and hence its ability to bind cellular partners. Our report suggests that functionally and conformationally distinct Nef isoforms modulate HIV replication on the interaction level with the TCR-signaling environment once the virus enters the T cell compartment.
authors.affiliation: Institute for Hygiene, Department of Virology, University of Heidelberg, D-69120, Heidelberg, Germany.
authors.forename: O T
authors.initials: OT
authors.lastname: Fackler
authors.forename: D
authors.initials: D
authors.lastname: Wolf
authors.forename: H O
authors.initials: HO
authors.lastname: Weber
authors.forename: B
authors.initials: B
authors.lastname: Laffert
authors.forename: P
authors.initials: P
authors.lastname: D'Aloja
authors.forename: B
authors.initials: B
authors.lastname: Schuler-Thurner
authors.forename: R
authors.initials: R
authors.lastname: Geffin
authors.forename: K
authors.initials: K
authors.lastname: Saksela
authors.forename: M
authors.initials: M
authors.lastname: Geyer
authors.forename: B M
authors.initials: BM
authors.lastname: Peterlin
authors.forename: G
authors.initials: G
authors.lastname: Schuler
authors.forename: A S
authors.initials: AS
authors.lastname: Baur
mesh_terms: D020816:Amino Acid Motifs; D015704:CD4 Antigens / Q000378:metabolism; D016827:CD8 Antigens / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003713:Dendritic Cells / Q000502:physiology; D015693:Gene Products, nef / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015497:HIV-1 / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D008958:Models, Molecular; D011233:Precipitin Tests; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000502:physiology* / Q000821:virology; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D015693:Gene Products, nef; D020033:Protein Isoforms; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)