Ee. Morrison et al., PHOSPHORYLATION OF STRUCTURAL COMPONENTS PROMOTES DISSOCIATION OF THEHERPES-SIMPLEX VIRUS TYPE-1 TEGUMENT, Journal of virology, 72(9), 1998, pp. 7108-7114
The role of phosphorylation in the dissociation of structural componen
ts of the herpes simplex virus type 1 (HSV-1) tegument was investigate
d, using an in vitro assay. Addition of physiological concentrations o
f ATP and magnesium to wild-type virions in the presence of detergent
promoted the release of VP13/14 and VP22. VP1/2 and the UL13 protein k
inase were not significantly solubilized. However, using a virus with
an inactivated UL13 protein, we found that the release of VP22 was sev
erely impaired. Addition of casein kinase II (CKII) to UL13 mutant vir
ions promoted VP22 release. Heat inactivation of virions or addition o
f phosphatase inhibited the release of both proteins. Incorporation of
radiolabeled ATP into the assay demonstrated the phosphorylation of V
P1/2, VP13/14, VP16, and VP22. Incubation of detergent-purified, heat-
inactivated capsid-tegument with recombinant kinases shelved VP1/2 pho
sphorylation by CKII, VP13/14 phosphorylation by CKII, protein kinase
A (PKA), and PKC, VP16 phosphorylation by PKA, and VP22 phosphorylatio
n by CKII and PKC. Proteolytic mapping and phosphoamino acid analysis
of phosphorylated VP22 correlated with previously published work The p
hosphorylation of virion-associated VP13/14, VP16, and VP22 was demons
trated in cells infected in the presence of cycloheximide. Use of equi
ne herpesvirus 1 in the in vitro release assay resulted in the enhance
d release of VP10, the homolog of HSV-1 VP13/14. These results suggest
that the dissociation of major tegument proteins from alphaherpesviru
s virions in infected cells may be initiated by phosphorylation events
mediated by both virion-associated and cellular kinases.