title: A Conserved GPG-Motif in the HIV-1 Nef Core Is Required for Principal Nef-Activities.
abstract: 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.
authors.affiliation: Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Martínez-Bonet
authors.affiliation: Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain.
authors.forename: Claudia
authors.initials: C
authors.lastname: Palladino
authors.affiliation: Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain.
authors.forename: Veronica
authors.initials: V
authors.lastname: Briz
authors.affiliation: Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Jochen M
authors.initials: JM
authors.lastname: Rudolph
authors.affiliation: Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Fackler
authors.affiliation: Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Relloso
authors.affiliation: Laboratorio de Inmunobiología Molecular, Instituto de Investigación Biomédica Gregorio Marañón (IISGM), 28007 Madrid, Spain.
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Muñoz-Fernandez
authors.affiliation: Departament of Virology. Centro de Biología Molecular Severo Ochoa, CSIC/UAM, Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Madrid
mesh_terms: D020816:Amino Acid Motifs; D015497:HIV-1 / Q000235:genetics / Q000472:pathogenicity; D006367:HeLa Cells; D006801:Humans; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000821:virology; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1