Phosphorylated protein component present in influenza virions

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Influenza nucleoprotein (NP) is a crucial component of the viral ribonucleoprotein complex.
• Understanding post-translational modifications of NP is essential for elucidating viral replication mechanisms.

Purpose of the Study:

• To investigate the in vitro phosphorylation of the WSN strain influenza nucleoprotein.
• To characterize the nature of the phosphate-protein linkage and identify the phosphorylated amino acid residue.

Main Methods:

• In vitro phosphorylation assays using purified WSN influenza nucleoprotein.
• Treatment with various chemical and enzymatic agents (TCA, RNase, DNase, alkaline phosphatase).
• Acid hydrolysis and thin-layer electrophoresis for amino acid residue identification.

Main Results:

• WSN influenza nucleoprotein was successfully phosphorylated in vitro.
• The phosphate-protein bond demonstrated stability to several harsh conditions but was sensitive to alkaline phosphatase.
• Phosphoserine was identified as the phosphorylated amino acid residue, suggesting a phosphomonoester linkage.

Conclusions:

• The nucleoprotein of the WSN strain of influenza is a phosphoprotein.
• Phosphorylation occurs via a phosphomonoester bond, specifically on a serine residue.
• These findings contribute to understanding the post-translational modifications of influenza nucleoprotein.