Variable-loop-deleted variants of the human immunodeficiency virus type 1 envelope glycoprotein can be stabilized by an intermolecular disulfide bond between the gp120 and gp41 subunits.
We have described an oligomeric gp140 envelope glycoprotein from human immunodeficiency virus type 1 that is stabilized by an intermolecular disulfide bond between gp120 and the gp41 ectodomain, termed SOS gp140 (J. M. Binley, R. W. Sanders, B. Clas, N. Schuelke, A. Master, Y. Guo, F. Kajumo, D. J. Anselma, P. J. Maddon, W. C. Olson, and J. P. Moore, J. Virol. 74:627-643, 2000). In this protein, the protease cleavage site between gp120 and gp41 is fully utilized. Here we report the characterization of gp140 variants that have deletions in the first, second, and/or third variable loop (V1, V2, and V3 loops). The SOS disulfide bond formed efficiently in gp140s containing a single loop deletion or a combination deletion of the V1 and V2 loops. However, deletion of all three variable loops prevented formation of the SOS disulfide bond. Some variable-loop-deleted gp140s were not fully processed to their gp120 and gp41 constituents even when the furin protease was cotransfected. The exposure of the gp120-gp41 cleavage site is probably affected in these proteins, even though the disabling change is in a region of gp120 distal from the cleavage site. Antigenic characterization of the variable-loop-deleted SOS gp140 proteins revealed that deletion of the variable loops uncovers cryptic, conserved neutralization epitopes near the coreceptor-binding site on gp120. These modified, disulfide-stabilized glycoproteins might be useful as immunogens.
Sanders
R W
RW
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
Schiffner
L
L
Master
A
A
Kajumo
F
F
Guo
Y
Y
Dragic
T
T
Moore
J P
JP
Binley
J M
JM
D000595:Amino Acid Sequence; D001665:Binding Sites; D015704:CD4 Antigens / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D018985:Epitopes, B-Lymphocyte; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011499:Protein Processing, Post-Translational; D054299:env Gene Products, Human Immunodeficiency Virus
D015704:CD4 Antigens; D004220:Disulfides; D018985:Epitopes, B-Lymphocyte; D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D054299:env Gene Products, Human Immunodeficiency Virus; C097729:gp140 envelope protein, Human immunodeficiency virus 1