The amino terminus of Epstein-Barr virus glycoprotein gH is important for fusion with epithelial and B cells.
Epstein-Barr virus (EBV) infects B lymphocytes and epithelial cells. While the glycoproteins required for entry into these two cell types differ, the gH/gL glycoprotein complex is essential for entry into both epithelial and B cells. Analysis of gH protein sequences from three gammaherpesviruses (EBV, marmoset, and rhesus) revealed a potential coiled-coil domain in the N terminus. Four leucines located in this region in EBV gH were replaced by alanines by site-directed mutagenesis and analyzed for cell-cell membrane fusion with B cells and epithelial cells. Reduction in fusion activity was observed for mutants containing L65A and/or L69A mutations, while substitutions in L55 and L74 enhanced the fusion activity of the mutant gH/gL complexes with both cell types. All of the mutants displayed levels of cell surface expression similar to those of wild-type gH and interacted with gL and gp42. The observation that a conservative mutation of leucine to alanine in the N terminus of EBV gH results in fusion-defective mutant gH/gL complexes is striking and points to an important role for this region in EBV-mediated membrane fusion with B lymphocytes and epithelial cells.
Omerović
Jasmina
J
Department of Microbiology and Immunology, The Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
Lev
Lori
L
Longnecker
Richard
R
D019943:Amino Acid Substitution; D000818:Animals; D001402:B-Lymphocytes / Q000821:virology*; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D006224:Cricetinae; D004847:Epithelial Cells / Q000821:virology*; D006023:Glycoproteins / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D008561:Membrane Fusion; D008562:Membrane Glycoproteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D014764:Viral Proteins / Q000378:metabolism
C101688:BZLF2 protein, Herpesvirus 4, Human; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C065527:glycoprotein H, Herpesvirus 4; C103802:glycoprotein L, Human herpesvirus 4