Identification of human immunodeficiency virus type 1 (HIV-1) gp120-binding sites on scavenger receptor cysteine rich 1 (SRCR1) domain of gp340

CD4 is the primary receptor for the human immunodeficiency virus type 1 (HIV-1). Early mutational studies implicated a number of residues of CD4, centered in the region 41-59, in binding to gp120. However, further mutational analyses, together with studies using inhibitory antibodies or CD4-derived peptides, have suggested that other regions of CD4 are also involved in binding or postbinding events during infection. To resolve these ambiguities, we used rat CD4 mutants in which particular regions were replaced with the corresponding sequence of human CD4. We have previously shown that some of these are able to bind HIV-1 gp120, and here we test their ability to act as functional receptors. We find that the presence of human CD4 residues 33-62 is enough to confer efficient receptor function to rat CD4, and we conclude that it is unlikely that regions of CD4 outside this sequence are involved in specific interactions with HIV-1 during either infection or syncytium formation.

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Naturally Occurring Human Immunodeficiency Virus Type 1 Long Terminal Repeats Have a Frequently Observed Duplication That Binds RBF-2 and Represses Transcription

Journal of Virology ◽

10.1128/jvi.72.8.6465-6474.1998 ◽

1998 ◽

Vol 72 (8) ◽

pp. 6465-6474 ◽

Cited By ~ 26

Author(s):

Mario Clemente Estable ◽

Brendan Bell ◽

Martin Hirst ◽

Ivan Sadowski

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Naturally Occurring ◽

Immunodeficiency Virus ◽

Aids Study ◽

Hiv 1 ◽

In Cells

ABSTRACT Approximately 38% of human immunodeficiency virus type 1 (HIV-1)-infected patients within the Vancouver Lymphadenopathy-AIDS Study have proviruses bearing partial 15- to 34-nucleotide duplications upstream of the NF-κB binding sites within the 5′ long terminal repeat (LTR). This most frequent naturally occurring length polymorphism (MFNLP) of the HIV-1 5′ LTR encompasses potential binding sites for several candidate transcription factors, including TCF-1α/hLEF, c-Ets, AP-4, and Ras-responsive binding factor 2 (RBF-2) (M. C. Estable et al., J. Virol. 70:4053–4062, 1996). RBF-2 and an apparently related factor, RBF-1, bind to at least fourcis elements within the LTR which are required for full transcriptional responsiveness to protein-tyrosine kinases and v-Ras (B. Bell and I. Sadowski, Oncogene 13:2687–2697, 1996). Here we demonstrate that representative MFNLPs from two patients specifically bind RBF-2. In both cases, deletion of the MFNLP caused elevated LTR-directed transcription in cells expressing RBF-2 but not in cells with undetectable RBF-2. RBF-1, but not RBF-2, appears to contain the Ets transcription factor family member GABPα/GABPβ1. Taken together with the fact that every MFNLP from a comparative study of over 500 LTR sequences from 42 patients contains a predicted binding site for RBF-2, our data suggest that the MFNLP is selected in vivo because it provides a duplicated RBF-2 cis element, which may limit transcription in monocytes and activated T cells.

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Mapping the RNA binding sites for human immunodeficiency virus type-1 Gag and NC proteins within the complete HIV-1 and -2 untranslated leader regions

Nucleic Acids Research ◽

10.1093/nar/26.16.3667 ◽

1998 ◽

Vol 26 (16) ◽

pp. 3667-3676 ◽

Cited By ~ 58

Author(s):

C. K. Damgaard ◽

H. Dyhr-Mikkelsen ◽

J. Kjems

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Rna Binding ◽

Immunodeficiency Virus ◽

Hiv 1 ◽

Rna Binding Sites

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Characterization of DC-SIGN/R Interaction with Human Immunodeficiency Virus Type 1 gp120 and ICAM Molecules Favors the Receptor's Role as an Antigen-Capturing Rather than an Adhesion Receptor

Journal of Virology ◽

10.1128/jvi.79.8.4589-4598.2005 ◽

2005 ◽

Vol 79 (8) ◽

pp. 4589-4598 ◽

Cited By ~ 62

Author(s):

Greg A. Snyder ◽

Jennifer Ford ◽

Parizad Torabi-Parizi ◽

James A. Arthos ◽

Peter Schuck ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Cell Surface ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Trojan Horse ◽

Gp120 Binding ◽

Immunodeficiency Virus ◽

Cell Surface Glycoproteins ◽

Hiv 1

ABSTRACT The dendritic cell (DC)-specific intercellular adhesion molecule 3 (ICAM-3)-grabbing nonintegrin binding receptor (DC-SIGN) was shown to bind human immunodeficiency virus type 1 (HIV-1) viral envelope protein gp120 and proposed to function as a Trojan horse to enhance trans-virus infection to host T cells. To better understand the mechanism by which DC-SIGN and DC-SIGNR selectively bind HIV-1 gp120, we constructed a series of deletion mutations in the repeat regions of both receptors. Different truncated receptors exist in different oligomeric forms. The carbohydrate binding domain without any repeats was monomeric, whereas the full extracellular receptors existed as tetramers. All reconstituted receptors retained their ability to bind gp120. The dissociation constant, however, differed drastically from micromolar values for the monomeric receptors to nanomolar values for the tetrameric receptors, suggesting that the repeat region of these receptors contributes to the avidity of gp120 binding. Such oligomerization may provide a mechanism for the receptor to selectively recognize pathogens containing multiple high-mannose-concentration carbohydrates. In contrast, the receptors bound to ICAMs with submicromolar affinities that are similar to those of two nonspecific cell surface glycoproteins, FcγRIIb and FcγRIII, and the oligomerization of DC-SIGNR resulted in no increase in binding affinity to ICAM-3. These findings suggest that DC-SIGN may not discriminate other cell surface glycoproteins from ICAM-3 binding. The pH dependence in DC-SIGN binding to gp120 showed that the receptor retained high-affinity gp120 binding at neutral pH but lost gp120 binding at pH 5, suggesting a release mechanism of HIV in the acidic endosomal compartment by DC-SIGN. Our work contradicts the function of DC-SIGN as a Trojan horse to facilitate HIV-1 infection; rather, it supports the function of DC-SIGN/R (a designation referring to both DC-SIGN and DC-SIGNR) as an antigen-capturing receptor.

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Stoichiometry of Monoclonal Antibody Neutralization of T-Cell Line-Adapted Human Immunodeficiency Virus Type 1

Journal of Virology ◽

10.1128/jvi.73.10.8364-8370.1999 ◽

1999 ◽

Vol 73 (10) ◽

pp. 8364-8370 ◽

Cited By ~ 39

Author(s):

Kristian Schønning ◽

Ole Lund ◽

Ole Søgaard Lund ◽

John-Erik Stig Hansen

Keyword(s):

Monoclonal Antibody ◽

Human Immunodeficiency Virus ◽

T Cell ◽

Cell Line ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT In order to study the stoichiometry of monoclonal antibody (MAb) neutralization of T-cell line-adapted human immunodeficiency virus type 1 (HIV-1) in antibody excess and under equilibrium conditions, we exploited the ability of HIV-1 to generate mixed oligomers when different env genes are coexpressed. By the coexpression of Env glycoproteins that either can or cannot bind a neutralizing MAb in an env transcomplementation assay, virions were generated in which the proportion of MAb binding sites could be regulated. As the proportion of MAb binding sites in Env chimeric virus increased, MAb neutralization gradually increased. Virus neutralization by virion aggregation was minimal, as MAb binding to HIV-1 Env did not interfere with an AMLV Env-mediated infection by HIV-1(AMLV/HIV-1) pseudotypes of CD4− HEK293 cells. MAb neutralization of chimeric virions could be described as a third-order function of the proportion of Env antigen refractory to MAb binding. This scenario is consistent with the Env oligomer constituting the minimal functional unit and neutralization occurring incrementally as each Env oligomer binds MAb. Alternatively, the data could be fit to a sigmoid function. Thus, these data could not exclude the existence of a threshold for neutralization. However, results from MAb neutralization of chimeric virus containing wild-type Env and Env defective in CD4 binding was readily explained by a model of incremental MAb neutralization. In summary, the data indicate that MAb neutralization of T-cell line-adapted HIV-1 is incremental rather than all or none and that each MAb binding an Env oligomer reduces the likelihood of infection.

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High-Mobility-Group Protein I Can Modulate Binding of Transcription Factors to the U5 Region of the Human Immunodeficiency Virus Type 1 Proviral Promoter

Journal of Virology ◽

10.1128/jvi.74.22.10523-10534.2000 ◽

2000 ◽

Vol 74 (22) ◽

pp. 10523-10534 ◽

Cited By ~ 24

Author(s):

Angus Henderson ◽

Michael Bunce ◽

Nicole Siddon ◽

Raymond Reeves ◽

David John Tremethick

Keyword(s):

Human Immunodeficiency Virus ◽

Transcription Factor ◽

Dna Binding ◽

Binding Site ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT HMG I/Y appears to be a multifunctional protein that relies on in its ability to interact with DNA in a structure-specific manner and with DNA, binding transcriptional activators via distinct protein-protein interaction surfaces. To investigate the hypothesis that HMG I/Y may have a role in human immunodeficiency virus type 1 (HIV-1) expression, we have analyzed whether HMG I/Y interacts with the 5′ long terminal repeat and whether this interaction can modulate transcription factor binding. Using purified recombinant HMG I, we have identified several high-affinity binding sites which overlap important transcription factor binding sites. One of these HMG I binding sites coincides with an important binding site for AP-1 located downstream of the transcriptional start site, in the 5′ untranslated region at the boundary of a positioned nucleosome. HMG I binding to this composite site inhibits the binding of recombinant AP-1. Consistent with this observation, using nuclear extracts prepared from Jurkat T cells, we show that HMG I (but not HMG Y) is strongly induced upon phorbol myristate acetate stimulation and this induced HMG I appears to both selectively inhibit the binding of basal DNA-binding proteins and enhance the binding of an inducible AP-1 transcription factor to this AP-1 binding site. We also report the novel finding that a component present in this inducible AP-1 complex is ATF-3. Taken together, these results argue that HMG I may play a fundamental role in HIV-1 expression by determining the nature of transcription factor-promoter interactions.

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Concordant Modulation of Neutralization Resistance and High Infectivity of the Primary Human Immunodeficiency Virus Type 1 MN Strain and Definition of a Potential gp41 Binding Site in gp120

Journal of Virology ◽

10.1128/jvi.77.1.560-570.2003 ◽

2003 ◽

Vol 77 (1) ◽

pp. 560-570 ◽

Cited By ~ 23

Author(s):

Maria Leavitt ◽

Eun Ju Park ◽

Igor A. Sidorov ◽

Dimiter S. Dimitrov ◽

Gerald V. Quinnan,

Keyword(s):

Human Immunodeficiency Virus ◽

Binding Site ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Leucine Zipper ◽

Immunodeficiency Virus ◽

Hiv 1 ◽

High Infectivity

ABSTRACT Efforts to develop a vaccine against human immunodeficiency virus type 1 (HIV-1) are complicated by resistance of virus to neutralization. The neutralization resistance phenotype of HIV-1 has been linked to high infectivity. We studied the mechanisms determining this phenotype using clones of the T-cell-line-adapted (TCLA) MN strain (MN-TCLA) and the neutralization-resistant, primary MN strain (MN-P). Mutations in the amino- and carboxy-terminal halves of gp120 and the carboxy terminus of gp41 contributed to the neutralization resistance, high-infectivity phenotype but depended upon sequences in the leucine zipper (LZ) domain of gp41. Among 23 clones constructed to map the contributing mutations, there was a very strong correlation between infectivity and neutralization resistance (R 2 = 0.81; P < 0.0001). Mutations that distinguished the gp120s of MN-P and MN-TCLA clones were clustered in or near the CD4 and coreceptor binding sites and in regions distant from those binding sites. To test the hypothesis that some of these distant mutations may interact with gp41, we determined which of them contributed to high infectivity and whether those mutations modulated gp120-gp41 association in the context of MN-P LZ sequences. In one clone, six mutations in the amino terminus of gp120, at least four of which clustered closely on the inner domain, modulated infectivity. This clone had a gp120-gp41 association phenotype like MN-P: in comparison to MN-TCLA, spontaneous dissociation was low, and dissociation induced by soluble CD4 binding was high. These results identify a region of the gp120 inner domain that may be a binding site for gp41. Our studies clarify mechanisms of primary virus neutralization resistance.

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Loss of a Single N-Linked Glycan Allows CD4-Independent Human Immunodeficiency Virus Type 1 Infection by Altering the Position of the gp120 V1/V2 Variable Loops

Journal of Virology ◽

10.1128/jvi.75.7.3435-3443.2001 ◽

2001 ◽

Vol 75 (7) ◽

pp. 3435-3443 ◽

Cited By ~ 130

Author(s):

Peter Kolchinsky ◽

Enko Kiprilov ◽

Peter Bartley ◽

Roee Rubinstein ◽

Joseph Sodroski

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Glycosylation Site ◽

Ccr5 Chemokine Receptor ◽

Gp120 Binding ◽

Immunodeficiency Virus ◽

Variable Loops ◽

Hiv 1

ABSTRACT The gp120 envelope glycoprotein of primary human immunodeficiency virus type 1 (HIV-1) promotes virus entry by sequentially binding CD4 and the CCR5 chemokine receptor on the target cell. Previously, we adapted a primary HIV-1 isolate, ADA, to replicate in CD4-negative canine cells expressing human CCR5. The gp120 changes responsible for CD4-independent replication were limited to the V2 loop-V1/V2 stem. Here we show that elimination of a single glycosylation site at asparagine 197 in the V1/V2 stem is sufficient for CD4-independent gp120 binding to CCR5 and for HIV-1 entry into CD4-negative cells expressing CCR5. Deletion of the V1/V2 loops also allowed CD4-independent viral entry and gp120 binding to CCR5. The binding of the wild-type ADA gp120 to CCR5 was less dependent upon CD4 at 4°C than at 37°C. In the absence of the V1/V2 loops, neither removal of the N-linked carbohydrate at asparagine 197 nor lowering of the temperature increased the CD4-independent phenotypes. A CCR5-binding conformation of gp120, achieved by CD4 interaction or by modification of temperature, glycosylation, or variable loops, was preferentially recognized by the monoclonal antibody 48d. These results suggest that the CCR5-binding region of gp120 is occluded by the V1/V2 variable loops, the position of which can be modulated by temperature, CD4 binding, or an N-linked glycan in the V1/V2 stem.

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Alanine Substitutions of Polar and Nonpolar Residues in the Amino-Terminal Domain of CCR5 Differently Impair Entry of Macrophage- and Dualtropic Isolates of Human Immunodeficiency Virus Type 1

Journal of Virology ◽

10.1128/jvi.72.4.3464-3468.1998 ◽

1998 ◽

Vol 72 (4) ◽

pp. 3464-3468 ◽

Cited By ~ 98

Author(s):

Gwénaël E. E. Rabut ◽

Jason A. Konner ◽

Francis Kajumo ◽

John P. Moore ◽

Tatjana Dragic

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Amino Terminal ◽

Terminal Domain ◽

Gp120 Binding ◽

Immunodeficiency Virus ◽

Amino Terminal Domain ◽

Hiv 1

ABSTRACT Multiple extracellular domains of the CC-chemokine receptor CCR5 are important for its function as a human immunodeficiency virus type 1 (HIV-1) coreceptor. We have recently demonstrated by alanine scanning mutagenesis that the negatively charged residues in the CCR5 amino-terminal domain are essential for gp120 binding and coreceptor function. We have now extended our analysis of this domain to include most polar and nonpolar amino acids. Replacement of alanine with all four tyrosine residues and with serine-17 and cysteine-20 decrease or abolish gp120 binding and CCR5 coreceptor activity. Tyrosine-15 is essential for viral entry irrespective of the test isolate. Substitutions at some of the other positions impair the entry of dualtropic HIV-1 isolates more than that of macrophagetropic ones.

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