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Identification of a CD36-related thrombospondin 1-binding domain in HIV-1 envelope glycoprotein gp120: relationship to HIV-1-specific inhibitory factors in human saliva.

Crombie R, Silverstein RL, MacLow C, Pearce SF, Nachman RL, Laurence J - J. Exp. Med. (1998)

Bottom Line: In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines.Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity.Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, The New York Hospital-Cornell Medical Center, New York 10021, USA.

ABSTRACT
Human and non-human primate salivas retard the infectivity of HIV-1 in vitro and in vivo. Because thrombospondin 1 (TSP1), a high molecular weight trimeric glycoprotein, is concentrated in saliva and can inhibit the infectivity of diverse pathogens in vitro, we sought to determine the role of TSP1 in suppression of HIV infectivity. Sequence analysis revealed a TSP1 recognition motif, previously defined for the CD36 gene family of cell adhesion receptors, in conserved regions flanking the disulfide-linked cysteine residues of the V3 loop of HIV envelope glycoprotein gp120, important for HIV binding to its high affinity cellular receptor CD4. Using solid-phase in vitro binding assays, we demonstrate direct binding of radiolabeled TSP1 to immobilized recombinant gp120. Based on peptide blocking experiments, the TSP1-gp120 interaction involves CSVTCG sequences in the type 1 properdin-like repeats of TSP1, the known binding site for CD36. TSP1 and fusion proteins derived from CD36-related TSP1-binding domains were able to compete with radiolabeled soluble CD4 binding to immobilized gp120. In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines. Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity. Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.

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Amino acid sequence alignment of CD36/LIMPII TSP-binding motifs with homologous sequences in HIV-1 gp120. Results of a  pattern-based blast enhanced alignment utility search (BEAUTY) that  matched a split motif in gp120 domains C2 (top) and C3 (bottom). *, indicates disulfide-bonded cysteine residues of the V3 loop. The brackets  above alignments show boundaries of CD36 exon 5 coding region  (CD36 aa 95–143). Amino acids identical between HIV-1 gp120 and either CD36 or LIMPII are highlighted white on black. Bold residues represent conservative substitutions according to the following groups: basic  (KRH), acidic (DE), charged (KRH, DE), aromatic (YFW), hydroxy  (STY), aliphatic (AG), nonpolar/branched (IVL), hydrophobic (AGP,  IVL, FM), polar/hydrophilic (ST, KRH, DNEQ, CWY), X = any aa, period = gap. These sequence data are available from GenBank/EMBL/ DDBJ under accession numbers: huCD36, M24795; huLIMPII, D12676;  HIV-1, partial sequence of isolate U37041. HIV-1 clade B consensus,  MN, and LAI isolate sequences were retrieved from the WHO HIV Sequence Database.
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Figure 1: Amino acid sequence alignment of CD36/LIMPII TSP-binding motifs with homologous sequences in HIV-1 gp120. Results of a pattern-based blast enhanced alignment utility search (BEAUTY) that matched a split motif in gp120 domains C2 (top) and C3 (bottom). *, indicates disulfide-bonded cysteine residues of the V3 loop. The brackets above alignments show boundaries of CD36 exon 5 coding region (CD36 aa 95–143). Amino acids identical between HIV-1 gp120 and either CD36 or LIMPII are highlighted white on black. Bold residues represent conservative substitutions according to the following groups: basic (KRH), acidic (DE), charged (KRH, DE), aromatic (YFW), hydroxy (STY), aliphatic (AG), nonpolar/branched (IVL), hydrophobic (AGP, IVL, FM), polar/hydrophilic (ST, KRH, DNEQ, CWY), X = any aa, period = gap. These sequence data are available from GenBank/EMBL/ DDBJ under accession numbers: huCD36, M24795; huLIMPII, D12676; HIV-1, partial sequence of isolate U37041. HIV-1 clade B consensus, MN, and LAI isolate sequences were retrieved from the WHO HIV Sequence Database.

Mentions: Deduced amino acid sequences encoded by exon 5 of CD36 or homolog LIMPII (Fig. 1) that contain previously characterized TSP1-binding motifs (35) were used as query for a BLAST-enhanced alignment utility search (BEAUTY; reference 37), which incorporates pattern-induced multiple alignment (PIMA; reference 38) sequence family clusters, conserved cluster domains, and PROSITE annotated libraries (39). HIV-1 consensus and subtype sequence alignments were retrieved from the Los Alamos Sequence Database.


Identification of a CD36-related thrombospondin 1-binding domain in HIV-1 envelope glycoprotein gp120: relationship to HIV-1-specific inhibitory factors in human saliva.

Crombie R, Silverstein RL, MacLow C, Pearce SF, Nachman RL, Laurence J - J. Exp. Med. (1998)

Amino acid sequence alignment of CD36/LIMPII TSP-binding motifs with homologous sequences in HIV-1 gp120. Results of a  pattern-based blast enhanced alignment utility search (BEAUTY) that  matched a split motif in gp120 domains C2 (top) and C3 (bottom). *, indicates disulfide-bonded cysteine residues of the V3 loop. The brackets  above alignments show boundaries of CD36 exon 5 coding region  (CD36 aa 95–143). Amino acids identical between HIV-1 gp120 and either CD36 or LIMPII are highlighted white on black. Bold residues represent conservative substitutions according to the following groups: basic  (KRH), acidic (DE), charged (KRH, DE), aromatic (YFW), hydroxy  (STY), aliphatic (AG), nonpolar/branched (IVL), hydrophobic (AGP,  IVL, FM), polar/hydrophilic (ST, KRH, DNEQ, CWY), X = any aa, period = gap. These sequence data are available from GenBank/EMBL/ DDBJ under accession numbers: huCD36, M24795; huLIMPII, D12676;  HIV-1, partial sequence of isolate U37041. HIV-1 clade B consensus,  MN, and LAI isolate sequences were retrieved from the WHO HIV Sequence Database.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199189&req=5

Figure 1: Amino acid sequence alignment of CD36/LIMPII TSP-binding motifs with homologous sequences in HIV-1 gp120. Results of a pattern-based blast enhanced alignment utility search (BEAUTY) that matched a split motif in gp120 domains C2 (top) and C3 (bottom). *, indicates disulfide-bonded cysteine residues of the V3 loop. The brackets above alignments show boundaries of CD36 exon 5 coding region (CD36 aa 95–143). Amino acids identical between HIV-1 gp120 and either CD36 or LIMPII are highlighted white on black. Bold residues represent conservative substitutions according to the following groups: basic (KRH), acidic (DE), charged (KRH, DE), aromatic (YFW), hydroxy (STY), aliphatic (AG), nonpolar/branched (IVL), hydrophobic (AGP, IVL, FM), polar/hydrophilic (ST, KRH, DNEQ, CWY), X = any aa, period = gap. These sequence data are available from GenBank/EMBL/ DDBJ under accession numbers: huCD36, M24795; huLIMPII, D12676; HIV-1, partial sequence of isolate U37041. HIV-1 clade B consensus, MN, and LAI isolate sequences were retrieved from the WHO HIV Sequence Database.
Mentions: Deduced amino acid sequences encoded by exon 5 of CD36 or homolog LIMPII (Fig. 1) that contain previously characterized TSP1-binding motifs (35) were used as query for a BLAST-enhanced alignment utility search (BEAUTY; reference 37), which incorporates pattern-induced multiple alignment (PIMA; reference 38) sequence family clusters, conserved cluster domains, and PROSITE annotated libraries (39). HIV-1 consensus and subtype sequence alignments were retrieved from the Los Alamos Sequence Database.

Bottom Line: In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines.Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity.Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, The New York Hospital-Cornell Medical Center, New York 10021, USA.

ABSTRACT
Human and non-human primate salivas retard the infectivity of HIV-1 in vitro and in vivo. Because thrombospondin 1 (TSP1), a high molecular weight trimeric glycoprotein, is concentrated in saliva and can inhibit the infectivity of diverse pathogens in vitro, we sought to determine the role of TSP1 in suppression of HIV infectivity. Sequence analysis revealed a TSP1 recognition motif, previously defined for the CD36 gene family of cell adhesion receptors, in conserved regions flanking the disulfide-linked cysteine residues of the V3 loop of HIV envelope glycoprotein gp120, important for HIV binding to its high affinity cellular receptor CD4. Using solid-phase in vitro binding assays, we demonstrate direct binding of radiolabeled TSP1 to immobilized recombinant gp120. Based on peptide blocking experiments, the TSP1-gp120 interaction involves CSVTCG sequences in the type 1 properdin-like repeats of TSP1, the known binding site for CD36. TSP1 and fusion proteins derived from CD36-related TSP1-binding domains were able to compete with radiolabeled soluble CD4 binding to immobilized gp120. In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines. Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity. Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.

Show MeSH
Related in: MedlinePlus