The amino terminus of herpes simplex virus type 1 glycoprotein K (gK) modulates gB-mediated virus-induced cell fusion and virion egress.
Herpes simplex virus type 1 (HSV-1)-induced cell fusion is mediated by viral glycoproteins and other membrane proteins expressed on infected cell surfaces. Certain mutations in the carboxyl terminus of HSV-1 glycoprotein B (gB) and in the amino terminus of gK cause extensive virus-induced cell fusion. Although gB is known to be a fusogenic glycoprotein, the mechanism by which gK is involved in virus-induced cell fusion remains elusive. To delineate the amino-terminal domains of gK involved in virus-induced cell fusion, the recombinant viruses gKDelta31-47, gKDelta31-68, and gKDelta31-117, expressing gK carrying in-frame deletions spanning the amino terminus of gK immediately after the gK signal sequence (amino acids [aa] 1 to 30), were constructed. Mutant viruses gKDelta31-47 and gKDelta31-117 exhibited a gK-null (DeltagK) phenotype characterized by the formation of very small viral plaques and up to a 2-log reduction in the production of infectious virus in comparison to that for the parental HSV-1(F) wild-type virus. The gKDelta31-68 mutant virus formed substantially larger plaques and produced 1-log-higher titers than the gKDelta31-47 and gKDelta31-117 mutant virions at low multiplicities of infection. Deletion of 28 aa from the carboxyl terminus of gB (gBDelta28syn) caused extensive virus-induced cell fusion. However, the gBDelta28syn mutation was unable to cause virus-induced cell fusion in the presence of the gKDelta31-68 mutation. Transient expression of a peptide composed of the amino-terminal 82 aa of gK (gKa) produced a glycosylated peptide that was efficiently expressed on cell surfaces only after infection with the HSV-1(F), gKDelta31-68, DeltagK, or UL20-null virus. The gKa peptide complemented the gKDelta31-47 and gKDelta31-68 mutant viruses for infectious-virus production and for gKDelta31-68/gBDelta28syn-mediated cell fusion. These data show that the amino terminus of gK modulates gB-mediated virus-induced cell fusion and virion egress.
Division of Biotechnology and Molecular Medicine, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Vladimir N
VN
Chouljenko
Arun V
AV
Iyer
Sona
S
Chowdhury
Dmitry V
DV
Chouljenko
Konstantin G
KG
Kousoulas
D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D002522:Chlorocebus aethiops; D015967:Gene Expression Regulation, Viral; D005816:Genetic Complementation Test; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000502:physiology*; D017384:Sequence Deletion; D014759:Viral Envelope Proteins / Q000502:physiology; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*
C072448:UL53 protein, Human herpesvirus 1; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C040495:glycoprotein B, Simplexvirus