Isolation and characterization of an extremely basic protein from adenovirus type 5

Area of Science:

• Virology
• Molecular Biology
• Protein Chemistry

Background:

• Adenovirus type 5 is a well-studied virus with known core proteins.
• Characterization of viral proteins is crucial for understanding viral structure and function.

Purpose of the Study:

• To identify and characterize novel basic polypeptides in adenovirus type 5.
• To investigate the properties and abundance of these newly discovered viral proteins.

Main Methods:

• Starch-gel electrophoresis with sensitive arginine staining.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
• Urea phosphocellulose column chromatography and Sephadex G-75 gel filtration.
• Amino acid analysis.

Main Results:

• Two minor basic polypeptides with high cathodic mobility were identified in adenovirus type 5 virions.
• The fastest migrating polypeptide, named mu protein, was found in virions and infected cells but not in top components or uninfected cells.
• Mu protein has a molecular weight of approximately 4,000, lacks tryptophan, and is composed of 69% basic amino acids (54% arginine, 13% histidine, 2% lysine).
• Mu protein is present at 125 copies per 1,000 copies of polypeptide VII.

Conclusions:

• Adenovirus type 5 possesses previously unidentified minor basic core proteins, including the mu protein.
• These proteins are integral components of the virion and are associated with viral infection.
• The unique amino acid composition and low molecular weight of mu protein suggest specialized functions within the adenovirus structure.