Fusion activity of lipid-anchored envelope glycoproteins of herpes simplex virus type 1.
Expression of the herpes simplex virus type 1 (HSV-1) glycoproteins gB, gD, gH, and gL is necessary and sufficient to cause cell fusion. To identify the requirements for a membrane-spanning domain in HSV-1 glycoprotein-induced cell fusion, we created gB, gD, and gH mutants with transmembrane and cytoplasmic domains replaced by a glycosylphosphatidylinositol (gpi)-addition sequence. The corresponding gBgpi, gDgpi, and gHgpi proteins were expressed with wild-type efficiency at the cell surface and were linked to the plasma membrane via a gpi anchor. The gDgpi mutant promoted cell fusion near wild-type gD levels when co-expressed with gB, gH, and gL in a cell-mixing fusion assay, indicating that the gD transmembrane and cytoplasmic domains were not required for fusion activity. A plasma membrane link was required for fusion because a gD mutant lacking a transmembrane and cytoplasmic domain was nonfunctional for fusion. The gDgpi mutant was also able to cooperate with wild-type gB, gH, and gL to form syncytia, albeit at a size smaller than those formed in the wild-type situation. The gBgpi and gHgpi mutants were unable to promote fusion when expressed with the other wild-type viral glycoproteins, highlighting the requirement of the specific transmembrane and cytoplasmic domains for gB and gH function.
Jones
Natasha A
NA
Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY 40536-0298, USA.
Geraghty
Robert J
RJ
D000818:Animals; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000502:physiology; D006224:Cricetinae; D017261:Glycosylphosphatidylinositols / Q000502:physiology*; D018259:Herpesvirus 1, Human / Q000502:physiology*; D008561:Membrane Fusion; D000075983:Nectins; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000502:physiology; D010957:Plasmids; D014759:Viral Envelope Proteins / Q000502:physiology*
D015815:Cell Adhesion Molecules; D017261:Glycosylphosphatidylinositols; D000075983:Nectins; D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; C039447:glycoprotein D, Human herpesvirus 1; C044200:glycoprotein H, herpes simplex virus type 1; D043265:Phosphatidylinositol Diacylglycerol-Lyase