Study of the interaction of HIV-1 and HIV-2 envelope glycoproteins with the CD4 receptor and role of N-glycans.
In order to further characterize the interaction of human immunodeficiency viruses (HIV) with the CD4 receptor at the molecular level, a binding test was performed using iodine-labeled glycoproteins, 125I-gp160 from HIV-1 and 125I-gp140 from HIV-2, to bind to lymphoid cells expressing the CD4 receptor. The inhibition of binding of the radiolabeled glycoproteins to CD4+ cells by increasing concentrations of nonradiolabeled gp160 or gp140 was used to determine the affinity of the interaction between the glycoproteins and CD4. The gp-CD4 association occurs with a high affinity: K0.5 gpHIV-1 = 9 x 10(-9) M and K0.5 gpHIV-2 = 7 x 10(-8) M, indicating that the affinity of the interaction between HIV-2 gp140 and CD4 is 10 times lower than that observed with HIV-1 gp160. The N-linked glycans of the HIV-1 and HIV-2 glycoproteins account for a high proportion of their molecular mass (about 50%). Total deglycosylation of gp160 and gp140 by enzymatic treatment with Endo F-N glycanase occurred under nondenaturing conditions, indicating the high accessibility of the N-linked glycan chains in the three-dimensional structure of the molecule. Moreover, the deglycosylated proteins retained a significant binding capacity to CD4. These results show that the carbohydrate chains of HIV-2 gp140, as those of HIV-1 gp160, do not play a major role in the gp-CD4 interaction.
Bahraoui
E
E
CNRS URA 1455, Faculté de Médecine Nord, Marseille, France.
Benjouad
A
A
Guetard
D
D
Kolbe
H
H
Gluckman
J C
JC
Montagnier
L
L
D015704:CD4 Antigens / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005434:Flow Cytometry; D015686:Gene Products, env / Q000737:chemistry / Q000378:metabolism*; D015726:Giant Cells / Q000382:microbiology; D006031:Glycosylation; D019302:HIV Envelope Protein gp160; D015497:HIV-1 / Q000378:metabolism*; D015498:HIV-2 / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D011863:Radioimmunoassay; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D054299:env Gene Products, Human Immunodeficiency Virus
D015704:CD4 Antigens; D015686:Gene Products, env; D019302:HIV Envelope Protein gp160; D011134:Polysaccharides; D011498:Protein Precursors; D011994:Recombinant Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; C066315:gp140 envelope protein, Human immunodeficiency virus 2