Protein Kinase Activity in Purified Poliovirus Particles and Empty Viral Capsid Preparations

Abstract

SUMMARYPreparations of purified poliovirus type 1, strain Mahoney, and empty viral capsids contain a protein kinase activity. The y-phosphoryl group of [32p]AT P is transferred to all of the capsid proteins. Viral proteins phosphorylated in vitro are recognized by antiserum directed against isolated viral capsid proteins, indicating that phosphorylation does not alter the antigenic sites to such an extent that the recognition by antibodies is abolished. Viral capsid protein phosphorylation exposes new antigenic sites and leads to a destabilization of the virions. The transfer of 32p to viral proteins is linear for 90 min at 37 °C in the presence of 10 mM-Mg 2 + at pH 8-1. Reducing agents or virus-stabilizing agents (such as arildone) reduce the kinase activity and result in a different pattern of capsid protein phosphorylation.

Properties of poliovirus associated protein kinase

“…In this report we provide further evidence for the tight association of the previously described protein kinase (29) and infectious poliovirus particles. Our data reveal that the enzyme copurifies with the infectious virus particles, i.e.…”

“…Therefore, the observed phosphoryIation of poliovirus capsid proteins is most likely due to the activity of small amounts of host cell enzyme(s), tightly associated with poliovirus particles (Fig. 2) and empty capsids (29).…”

“…Cells were grown and virus was prepared as previously described (29). Briefly, HeLa cells were infected with 5 to 10PFU of poliovirus/cell, incubated for 5 hours at 37°C and lysed.…”

“…Viral capsid protein phosphorylation was shown to expose new antigenic sites and to result in a destabilization of the virion, e.g. a reduced stability towards SDS (29). It is conceivable that a corresponding alteration of poliovirus eapsids occurs as soon as virus particles enter the cytoplasm and are exposed to ATP.…”

“…They have important functions in the regulation of enzyme activities (19), in the initiation of protein biosynthesis (25) and in the process of cell proliferation (13,22). Besides the well studied oneogene protein kinases, a number of virus associated protein kinases has been described, not only for enveloped viruses (2,4,5,11,13), but, also for adenoviruses (1,33) and pieornaviruses (10,29).…”