Comparative properties of bacteriophage phi6 and phi6 nucleocapsid

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Bacteriophage phi6 is an enveloped virus with a double-stranded RNA genome.
• Understanding viral structure and protein function is crucial for virology research.

Purpose of the Study:

• To characterize the nucleocapsid of bacteriophage phi6 after detergent treatment.
• To identify surface proteins and analyze the stability and composition of the nucleocapsid.

Main Methods:

• Nonionic detergent treatment to release the nucleocapsid.
• Sucrose density gradient sedimentation and cesium sulfate (Cs2SO4) buoyant density centrifugation.
• Surface iodination (125I) to label exposed proteins.
• pH stability assays and ethylenediaminetetraacetic acid (EDTA) dissociation experiments.

Main Results:

• Detergent treatment removed lipids and five outer proteins, yielding a stable nucleocapsid.
• The nucleocapsid exhibited a higher buoyant density (1.33 g/cm3) than the whole phage (1.22 g/cm3).
• Protein P3 was identified on the phage surface, while protein P8 was on the nucleocapsid surface.
• The nucleocapsid contained double-stranded RNA and RNA polymerase activity, dissociating in the presence of low EDTA concentrations.

Conclusions:

• Nonionic detergents effectively isolate the bacteriophage phi6 nucleocapsid.
• The nucleocapsid possesses distinct biophysical properties and contains essential viral components, including RNA polymerase.
• Specific proteins (P3 and P8) are localized to the outer surface of the phage and nucleocapsid, respectively.