A Conserved GPG-Motif in the HIV-1 Nef Core Is Required for Principal Nef-Activities

• Published in: PloS one 2015-12, Vol.10 (12), p.e0145239-e0145239
• Main Authors: Martínez-Bonet, Marta, Palladino, Claudia, Briz, Veronica, Rudolph, Jochen M, Fackler, Oliver T, Relloso, Miguel, Muñoz-Fernandez, Maria Angeles, Madrid, Ricardo
• Format: Article
• Language: English
• Subjects: Acquired immune deficiency syndrome; Actin; AIDS; Alanine; Amino Acid Motifs; Analysis; Care and treatment; CD4 antigen; Cloning; Gene expression; HeLa Cells; HIV; HIV infections; HIV-1 - genetics; HIV-1 - pathogenicity; Human immunodeficiency virus; Humans; Infections; Infectious diseases; Infectivity; Kinases; Lymphocytes; Lymphocytes T; Muscle proteins; Mutagenesis; nef Gene Products, Human Immunodeficiency Virus - chemistry; nef Gene Products, Human Immunodeficiency Virus - genetics; nef Gene Products, Human Immunodeficiency Virus - physiology; Nef protein; Phosphorylation; Plasma; Protein Structure, Tertiary; Protein transport; Protein-tyrosine kinase; Proteins; Recruitment; Risk factors; Signal transduction; Structure-Activity Relationship; T cell receptors; T cells; T-cell receptor; T-Lymphocytes - virology; Transcription factors; Viral infections; Virology; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0145239

To find out new determinants required for Nef activity we performed a functional alanine scanning analysis along a discrete but highly conserved region at the core of HIV-1 Nef. We identified the GPG-motif, located at the 121-137 region of HIV-1 NL4.3 Nef, as a novel protein signature strictly required for the p56Lck dependent Nef-induced CD4-downregulation in T-cells. Since the Nef-GPG motif was dispensable for CD4-downregulation in HeLa-CD4 cells, Nef/AP-1 interaction and Nef-dependent effects on Tf-R trafficking, the observed effects on CD4 downregulation cannot be attributed to structure constraints or to alterations on general protein trafficking. Besides, we found that the GPG-motif was also required for Nef-dependent inhibition of ring actin re-organization upon TCR triggering and MHCI downregulation, suggesting that the GPG-motif could actively cooperate with the Nef PxxP motif for these HIV-1 Nef-related effects. Finally, we observed that the Nef-GPG motif was required for optimal infectivity of those viruses produced in T-cells. According to these findings, we propose the conserved GPG-motif in HIV-1 Nef as functional region required for HIV-1 infectivity and therefore with a potential interest for the interference of Nef activity during HIV-1 infection.