Dissociation of the CD4 downregulation and viral infectivity enhancement functions of human immunodeficiency virus type 1 Nef. 1995

M A Goldsmith, and M T Warmerdam, and R E Atchison, and M D Miller, and W C Greene
Gladstone Institute of Virology and Immunology, School of Medicine, University of California San Francisco 94141, USA.

Recent evidence indicates that the nef gene of human immunodeficiency virus type 1 augments rather than inhibits viral replication in both cell culture and in vivo models. In addition, nef alters various normal cellular processes, including the display of CD4 on the cell surface. However, it remains unknown whether the enhancement of infectivity and the downregulation of CD4 represent linked or independent biologic properties of this single protein. In the present studies, mutational analyses were performed to define structure-function relationships within the Nef protein that mediate these effects. To assess the functional consequences of these mutations, sensitive and reliable assays were developed to quantitate the viral infectivity enhancement and CD4 downregulation functions of Nef. The results indicate that membrane-targeting sequences at the N terminus of Nef are important for both functions of Nef, while certain other conserved regions are dispensable for both functions. A conserved proline-X-X repeat segment in the central core of the protein, which is reminiscent of an SH3-binding domain, is critical for the enhancement of infectivity function but is dispensable for CD4 downregulation. However, the downregulation of CD4 by Nef appears to involve a two-step process requiring the initial dissociation of p56lck from CD4 to permit engagement of the endocytic apparatus by CD4. Together, these findings demonstrate that the infectivity enhancement and CD4 downregulation activities of human immunodeficiency virus type 1 Nef can be dissociated. Thus, these processes may be independent of one another in the viral replication cycle.

UI MeSH Term Description Entries
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D011505 Protein-Tyrosine Kinases Protein kinases that catalyze the PHOSPHORYLATION of TYROSINE residues in proteins with ATP or other nucleotides as phosphate donors. Tyrosine Protein Kinase,Tyrosine-Specific Protein Kinase,Protein-Tyrosine Kinase,Tyrosine Kinase,Tyrosine Protein Kinases,Tyrosine-Specific Protein Kinases,Tyrosylprotein Kinase,Kinase, Protein-Tyrosine,Kinase, Tyrosine,Kinase, Tyrosine Protein,Kinase, Tyrosine-Specific Protein,Kinase, Tyrosylprotein,Kinases, Protein-Tyrosine,Kinases, Tyrosine Protein,Kinases, Tyrosine-Specific Protein,Protein Kinase, Tyrosine-Specific,Protein Kinases, Tyrosine,Protein Kinases, Tyrosine-Specific,Protein Tyrosine Kinase,Protein Tyrosine Kinases,Tyrosine Specific Protein Kinase,Tyrosine Specific Protein Kinases
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001483 Base Sequence The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence. DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D015497 HIV-1 The type species of LENTIVIRUS and the etiologic agent of AIDS. It is characterized by its cytopathic effect and affinity for the T4-lymphocyte. Human immunodeficiency virus 1,HIV-I,Human Immunodeficiency Virus Type 1,Immunodeficiency Virus Type 1, Human
D015536 Down-Regulation A negative regulatory effect on physiological processes at the molecular, cellular, or systemic level. At the molecular level, the major regulatory sites include membrane receptors, genes (GENE EXPRESSION REGULATION), mRNAs (RNA, MESSENGER), and proteins. Receptor Down-Regulation,Down-Regulation (Physiology),Downregulation,Down Regulation,Down-Regulation, Receptor
D015693 Gene Products, nef Products of the retroviral NEF GENE. They play a role as accessory proteins that influence the rate of viral infectivity and the destruction of the host immune system. nef gene products were originally found as factors that trans-suppress viral replication and function as negative regulators of transcription. nef stands for negative factor. nef Gene Products,nef Protein,3'-orf Protein,Gene Product, nef,3' orf Protein,nef Gene Product
D015704 CD4 Antigens 55-kDa antigens found on HELPER-INDUCER T-LYMPHOCYTES and on a variety of other immune cell types. They are members of the immunoglobulin supergene family and are implicated as associative recognition elements in MAJOR HISTOCOMPATIBILITY COMPLEX class II-restricted immune responses. On T-lymphocytes they define the helper/inducer subset. T4 antigens also serve as INTERLEUKIN-15 receptors and bind to the HIV receptors, binding directly to the HIV ENVELOPE PROTEIN GP120. Antigens, CD4,CD4 Molecule,CD4 Receptor,CD4 Receptors,Receptors, CD4,T4 Antigens, T-Cell,CD4 Antigen,Receptors, Surface CD4,Surface CD4 Receptor,Antigen, CD4,Antigens, T-Cell T4,CD4 Receptor, Surface,CD4 Receptors, Surface,Receptor, CD4,Surface CD4 Receptors,T-Cell T4 Antigens,T4 Antigens, T Cell
D016297 Mutagenesis, Site-Directed Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion. Mutagenesis, Oligonucleotide-Directed,Mutagenesis, Site-Specific,Oligonucleotide-Directed Mutagenesis,Site-Directed Mutagenesis,Site-Specific Mutagenesis,Mutageneses, Oligonucleotide-Directed,Mutageneses, Site-Directed,Mutageneses, Site-Specific,Mutagenesis, Oligonucleotide Directed,Mutagenesis, Site Directed,Mutagenesis, Site Specific,Oligonucleotide Directed Mutagenesis,Oligonucleotide-Directed Mutageneses,Site Directed Mutagenesis,Site Specific Mutagenesis,Site-Directed Mutageneses,Site-Specific Mutageneses
D054311 nef Gene Products, Human Immunodeficiency Virus Proteins encoded by the NEF GENES of the HUMAN IMMUNODEFICIENCY VIRUS. nef Protein, Human Immunodeficiency Virus,HIV-3'-orf Protein,nef Protein, HIV,HIV 3' orf Protein,HIV nef Protein

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