An alpha-helical domain within the carboxyl terminus of herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) is associated with cell fusion and resistance to heparin inhibition of cell fusion.
Previous studies from our laboratory indicated that a 28-amino-acid carboxyl-terminal truncation of gB caused extensive virus-induced cell fusion (Baghian et al., 1993, J Virol 67, 2396-2401). We tested the ability of additional truncations and mutations within gB to cause cell fusion in the recently established virus-free cell fusion assay (Turner et al., 1998, J. Virol. 72, 873-875). Deletion of the carboxyl-terminal 28 amino acids of gB (gBDelta28), which removed part of the predicted alpha-helical structure H17b, caused extensive cell fusion. A gB truncation specified by gBDelta36, which removed the entire H17b domain, caused as much cell fusion as the gBDelta28 truncation. Similarly, gB(A874P) containing a substitution of an Ala with Pro within H17b caused cell fusion. Heparin, a gB-specific inhibitor of virus-induced cell fusion, inhibited both wild-type gB and gB(syn3)-mediated cell fusion. In contrast, fusion of cells transfected with gB(Delta28), gB(Delta36), or gB(A874P) was resistant to heparin inhibition of cell fusion. We concluded the following: (1) The predicted alpha-helical structure of H17b within the carboxyl terminus of gB is involved in both virus-induced and virus-free cell fusion. (2) Heparin is a specific inhibitor of gB-mediated fusion in both systems. (3) Resistance to heparin inhibition of gB-mediated cell fusion is associated with the predicted alpha-helical structure H17b within the carboxyl terminus of gB.
Foster
T P
TP
Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Melancon
J M
JM
Kousoulas
K G
KG
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D005455:Fluorescent Antibody Technique; D015726:Giant Cells / Q000821:virology; D006493:Heparin / Q000494:pharmacology*; D008561:Membrane Fusion / Q000187:drug effects*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship; D014162:Transfection; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry*
D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; D006493:Heparin