Identification of V3 loop-binding proteins as potential receptors implicated in the binding of HIV particles to CD4(+) cells.
The binding of human immunodeficiency virus (HIV) type 1 particles to CD4(+) cells could be blocked either by antibodies against the V3 loop domain of the viral external envelope glycoprotein gp120, or by the V3 loop mimicking pseudopeptide 5[Kpsi(CH2N)PR]-TASP, which forms a stable complex with a cell-surface-expressed 95-kDa protein. Here, by using an affinity matrix containing 5[Kpsi(CH2N)PR]-TASP and cytoplasmic extracts from human CEM cells, we purified three V3 loop-binding proteins of 95, 40, and 30 kDa, which after microsequencing were revealed to be as nucleolin, putative HLA class II-associated protein (PHAP) II, and PHAP I, respectively. The 95-kDa cell-surface protein was also isolated and found to be nucleolin. We show that recombinant preparations of gp120 bind the purified preparations containing the V3 loop-binding proteins with a high affinity, comparable to the binding of gp120 to soluble CD4. Such binding is inhibited either by 5[Kpsi(CH2N)PR]-TASP or antibodies against the V3 loop. Moreover, these purified preparations inhibit HIV entry into CD4(+) cells as efficiently as soluble CD4. Taken together, our results suggest that nucleolin, PHAP II, and PHAP I appear to be functional as potential receptors in the HIV binding process by virtue of their capacity to interact with the V3 loop of gp120.
Callebaut
C
C
Unité de Virologie et Immunologie Cellulaire, ERS 572 CNRS, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
Blanco
J
J
Benkirane
N
N
Krust
B
B
Jacotot
E
E
Guichard
G
G
Seddiki
N
N
Svab
J
J
Dam
E
E
Muller
S
S
Briand
J P
JP
Hovanessian
A G
AG
D000595:Amino Acid Sequence; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D056488:Histone Chaperones; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins; D010446:Peptide Fragments / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D015728:Receptors, HIV / Q000378:metabolism*; D014157:Transcription Factors; D014771:Virion / Q000378:metabolism*; D000097796:Nucleolin
D015704:CD4 Antigens; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D015699:HIV Envelope Protein gp120; D056488:Histone Chaperones; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; D011506:Proteins; D016601:RNA-Binding Proteins; D015728:Receptors, HIV; D014157:Transcription Factors; D000097796:Nucleolin; C087425:ANP32A protein, human; C059762:HIV envelope protein gp120 (305-321); C513473:SET protein, human