Tyrosine phosphorylation of measles virus P-phosphoprotein in persistently infected neuroblastoma cells

Abstract

Replication and encapsidation of measles virus (MV) requires the interaction between the nuclear protein (N) and the phosphoprotein (P). It is known that both proteins are phosphorylated on serine and threonine residues. Recently we have shown that N is phosphorylated on tyrosine in persistently-infected mouse neuroblastoma cells (NS20Y/MS). Here, we show that P in NS20Y/MS is also phosphorylated on tyrosine. To investigate whether cellular tyrosine kinases can bind and phosphorylate P, a solid phase kinase assay was employed. We show that bacterially-expressed MV P fragments, were phosphorylated on tyrosine by purified mouse c-Src protein-tyrosine kinase and when mixed with uninfected neuroblastoma cell (NS20Y) extracts, these P fragments were phosphorylated on tyrosine in addition to serine and threonine. These results imply that MV P is a substrate for tyrosine phosphorylation by cellular tyrosine kinase(s).

Measles

“…The vaccine strains also display changes in coding sequence in all viral proteins, few of them being common to all vaccine strains . Further-more, or alternatively, the mutation(s) within the virus 1991), the latter also being phosphorylated on Tyr residues in persistently infected neuroblastoma cells (Ofir et al 1996). Since then, there have been several attempts to adapt currently circulating wild-type MV strain to grow in CD150 -CD46 + Vero or CD150 -CD46 -CEF cells searching for the acquisition of common mutations that would sign the adaptation process.…”