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

Area of Science:

• Virology
• Molecular Biology
• Cellular Biology

Background:

• Measles virus (MV) replication and encapsidation depend on interactions between the nuclear protein (N) and phosphoprotein (P).
• Both N and P proteins are known to be phosphorylated on serine and threonine residues.
• Previous research indicated tyrosine phosphorylation of N in infected neuroblastoma cells (NS20Y/MS).

Purpose of the Study:

• To investigate the phosphorylation status of MV phosphoprotein (P) on tyrosine residues.
• To determine if cellular tyrosine kinases can bind to and phosphorylate MV P.
• To explore potential novel regulatory pathways in measles virus infection.

Main Methods:

• Utilized a solid phase kinase assay to assess P phosphorylation.
• Employed bacterially-expressed MV P fragments for in vitro assays.
• Used purified mouse c-Src protein-tyrosine kinase and uninfected neuroblastoma cell (NS20Y) extracts.

Main Results:

• MV P was found to be phosphorylated on tyrosine residues in infected NS20Y/MS cells.
• Bacterially-expressed MV P fragments were phosphorylated on tyrosine by purified c-Src kinase.
• MV P fragments were phosphorylated on tyrosine, serine, and threonine when incubated with NS20Y cell extracts.

Conclusions:

• Measles virus phosphoprotein (P) is a substrate for tyrosine phosphorylation by cellular tyrosine kinases.
• This identifies a novel post-translational modification of MV P.
• Suggests a potential role for tyrosine phosphorylation in regulating MV lifecycle and pathogenesis.