Regulation of vaccinia virus morphogenesis: Phosphorylation of the A14L and A17L membrane proteins and C-terminal truncation of the A17L protein are dependent on the F10L kinase
T. Betakova et al., Regulation of vaccinia virus morphogenesis: Phosphorylation of the A14L and A17L membrane proteins and C-terminal truncation of the A17L protein are dependent on the F10L kinase, J VIROLOGY, 73(5), 1999, pp. 3534-3543
This study focused on three vaccinia virus-encoded proteins that participat
e in early steps of virion morphogenesis: the A17L and A14L membrane protei
ns and the F10L protein kinase, We found that (i) the A17L protein was clea
ved at or near an AGX consensus motif at amino acid 185, thereby removing i
ts acidic C terminus; (ii) the nontruncated form was associated with immatu
re virions, but only the C-terminal truncated protein was present in mature
virions; (iii) the nontruncated form of the A17L protein was phosphorylate
d on serine, threonine, and tyrosine residues, whereas the truncated form w
as unphosphorylated; (iv) nontruncated and truncated forms of the A17L prot
ein existed in a complete with the A14L membrane protein; (v) C-terminal cl
eavage of the A17L protein and phosphorylation of the A17L and A14L protein
s failed to occur in cells infected with a F10L kinase mutant at the nonper
missive temperature; and (vi) the F10L kinase was the only viral late prote
in that was necessary for phosphorylation of the A17L protein, whereas addi
tional proteins were needed for C-terminal cleavage. We suggest that phosph
orylation of the A17L and A14L proteins is mediated by the F10L kinase and
is required to form the membranes associated with immature virions. Removal
of phosphates and the A17L acidic C-terminal peptide occur during the tran
sition to mature virions.