CHARACTERIZATION OF A BACULOVIRUS PROTEIN KINASE AND PHOSPHORYLATION AND DE-PHOSPHORYLATION OF THE VIRUS BASIC CORE PROTEIN
Wang Xunzhang Long Qingxin Xie Weidong Pang Yi Pu Zhelong( Instiiute of Entomology, Zhongshan University and National Loboratory of Biological Controt, Guangzhou,510275 )
Cell-released and polyhedron-derived forms of Trichoplusia ni Nuclear Polyhedrosis Virus ( TnNPV)particles possess protein kinase activity and the activity was not enhanced by cyclic nucleotide. The Mg++ cation and pH optima for the protein kinase activity,which catalyzes the pho sphate bound to serine and threonine, was determined and found to be not particularly stringent. Phosphorylation of the virus basie core protein were also found in this study, regardless of whether the kinases used were from virus particles or infected cell extracts and whether phosphorylation was carried out in vitro or in vivo.The demonstration that phosphory1ation of the basie protein occured in most cases but not detected in purified [32p] orthophosphate-labelled virus suggests that de-phosphorylation of the protein takes place before virus packaging. The role for de-phosphorylation of the basie protein is discussed.