M. Belyavskyi et al., THE STRUCTURAL PROTEIN ODV-EC27 OF AUTOGRAPHA-CALIFORNICA NUCLEOPOLYHEDROVIRUS IS A MULTIFUNCTIONAL VIRAL CYCLIN, Proceedings of the National Academy of Sciences of the United Statesof America, 95(19), 1998, pp. 11205-11210
Two major characteristics of baculovirus infection are arrest of the h
ost cell at G(2)/M phase of the cell cycle with continuing viral DNA r
eplication, We show that Autographa californica nucleopolyhedrovirus (
AcMNPV) encodes for a multifunctional cyclin that may partially explai
n the molecular basis of these important characteristics of AcMNPV (ba
culovirus) infection. Amino acids 80-110 of the viral structural prote
in ODV-EC27 (-EC27) demonstrate 25-30% similarity with cellular cyclin
s within the cyclin box. Immunoprecipitation results using antibodies
to -EC27 show that -EC27 can associate with either cdc2 or cdk6 result
ing in active kinase complexes that can phosphorylate histone H1 and r
etinoblastoma protein in vitro, The cdk6-EC27 complex also associates
with proliferating cell nuclear antigen (PCNA) and we demonstrate that
PCNA is a structural protein of both the budded virus and the occlusi
on-derived virus. These results suggest that -EC27 can function as a m
ultifunctional cyclin: when associated with cdc2, it exhibits cyclin B
-like activity; when associated with cdk6, the complex possesses cycli
n D-like activity and binds PCNA, The possible roles of such a multifu
nctional cyclin during the life cycle of baculovirus are discussed, al
ong with potential implications relative to the expression of function
ally authentic recombinant proteins by using baculovirus-infected cell
s.