Specific amino acids in the N-terminus of the gp41 ectodomain contribute to the stabilization of a soluble, cleaved gp140 envelope glycoprotein from human immunodeficiency virus type 1.
The HIV-1 envelope glycoprotein is expressed on the viral membrane as a trimeric complex, formed by three gp120 surface glycoproteins non-covalently associated with three membrane-anchored gp41 subunits. The labile nature of the association between gp120 and gp41 hinders the expression of soluble, fully cleaved, trimeric gp140 proteins for structural and immunization studies. Disruption of the primary cleavage site within gp160 allows the production of stable gp140 trimers, but cleavage-defective trimers are antigenically dissimilar from their cleaved counterparts. Soluble, stabilized, proteolytically cleaved, trimeric gp140 proteins can be generated by engineering an intermolecular disulfide bond between gp120 and gp41 (SOS), combined with a single residue change, I559P, within gp41 (SOSIP). We have found that SOSIP gp140 proteins based on the subtype A HIV-1 strain KNH1144 form particularly homogenous trimers compared to a prototypic strain (JR-FL, subtype B). We now show that the determinants of this enhanced stability are located in the N-terminal region of KNH11144 gp41 and that, when substituted into heterologous Env sequences (e.g., JR-FL and Ba-L) they have a similarly beneficial effect on trimer stability. The stabilized trimers retain the epitopes for several neutralizing antibodies (b12, 2G12, 2F5 and 4E10) and the CD4-IgG2 molecule, suggesting that the overall antigenic structure of the gp140 protein has not been adversely impaired by the trimer-stabilizing substitutions. The ability to increase the stability of gp140 trimers might be useful for neutralizing antibody-based vaccine strategies based on the use of this type of immunogen.
Dey
Antu K
AK
Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Avenue, Room W-805, New York, NY 10021, USA.
David
Kathryn B
KB
Klasse
Per J
PJ
Moore
John P
JP
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D016860:CD4 Immunoadhesins / Q000276:immunology; D002460:Cell Line; D000939:Epitopes / Q000276:immunology; D015686:Gene Products, env / Q000276:immunology / Q000378:metabolism*; D015483:HIV Antibodies / Q000276:immunology; D015700:HIV Envelope Protein gp41 / Q000737:chemistry*; D015497:HIV-1 / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D017434:Protein Structure, Tertiary / Q000502:physiology*; D016415:Sequence Alignment; D012995:Solubility; D013329:Structure-Activity Relationship; D054299:env Gene Products, Human Immunodeficiency Virus
D000911:Antibodies, Monoclonal; D016860:CD4 Immunoadhesins; D000939:Epitopes; D015686:Gene Products, env; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D054299:env Gene Products, Human Immunodeficiency Virus; C097729:gp140 envelope protein, Human immunodeficiency virus 1