Altering expression levels of human immunodeficiency virus type 1 gp120-gp41 affects efficiency but not kinetics of cell-cell fusion.
Human immunodeficiency virus (HIV) entry into a host cell requires the fusion of virus and cellular membranes that is driven by interaction of the viral envelope glycoproteins gp120 and gp41 (gp120/gp41) with CD4 and a coreceptor, typically either CXCR4 or CCR5. The stoichiometry of gp120/gp41:CD4:CCR5 necessary to initiate membrane fusion is not known. To allow an examination of early events in gp120/gp41-driven membrane fusion, we developed a novel real-time cell-cell fusion assay. Using this assay to study fusion kinetics, we found that altering the cell surface density of gp120/gp41 affected the maximal extent of fusion without dramatically altering fusion kinetics. Collectively, these observations are consistent with the view that gp120/gp41-driven membrane fusion requires the formation of a threshold number of fusion-active intercellular gp120/gp41:CD4:CCR5 complexes. Furthermore, the probability of reaching this threshold is governed, in part, by the surface density of gp120/gp41.
Lineberger
Janet E
JE
Department of Biological Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
Danzeisen
Renee
R
Hazuda
Daria J
DJ
Simon
Adam J
AJ
Miller
Michael D
MD
D002460:Cell Line; D005455:Fluorescent Antibody Technique; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008561:Membrane Fusion; D013997:Time Factors; D014760:Viral Fusion Proteins / Q000378:metabolism*; D014779:Virus Replication
D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D014760:Viral Fusion Proteins