gp120-independent fusion mediated by the human immunodeficiency virus type 1 gp41 envelope glycoprotein: a reassessment.
In a natural context, membrane fusion mediated by the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins involves both the exterior envelope glycoprotein (gp120) and the transmembrane glycoprotein (gp41). Perez et al. (J. Virol. 66:4134-4143, 1992) reported that a mutant HIV-1 envelope glycoprotein containing only the signal peptide and carboxyl terminus of the gp120 exterior glycoprotein fused to the complete gp41 glycoprotein was properly cleaved and that the resultant gp41 glycoprotein was able to induce the fusion of even CD4-negative cells. In the studies reported herein, mutant proteins identical or similar to those studied by Perez et al. lacked detectable cell fusion activity. The proteolytic processing of these proteins was very inefficient, and one processed product identified by Perez et al. as the authentic gp41 glycoprotein was shown to contain carboxyl-terminal gp120 sequences. Furthermore, no fusion activity was observed for gp41 glycoproteins exposed after shedding of the gp120 glycoprotein by soluble CD4. Thus, evidence supporting a gp120-independent cell fusion activity for the HIV-1 gp41 glycoprotein is currently lacking.
Marcon
L
L
Dana-Farber Cancer Institute, Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115.
Sodroski
J
J
D000595:Amino Acid Sequence; D015704:CD4 Antigens / Q000494:pharmacology; D002459:Cell Fusion / Q000187:drug effects; D015699:HIV Envelope Protein gp120 / Q000494:pharmacology / Q000502:physiology*; D015700:HIV Envelope Protein gp41 / Q000494:pharmacology / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D017384:Sequence Deletion; D014760:Viral Fusion Proteins / Q000494:pharmacology / Q000502:physiology*
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D014760:Viral Fusion Proteins