Isolation and identification of bacteriophage phi X174 prohead

Area of Science:

• Molecular Biology
• Virology
• Biochemistry

Background:

• Bacteriophage phi X174 morphogenesis is a complex process involving multiple viral proteins.
• Understanding the assembly pathway is crucial for comprehending viral replication strategies.

Purpose of the Study:

• To investigate the role of specific protein complexes in bacteriophage phi X174 morphogenesis.
• To identify the functional unit responsible for viral DNA synthesis and packaging in vitro.

Main Methods:

• Utilized an in vitro DNA synthesizing system with extracts from bacteriophage phi X174 B-mutant infected cells.
• Employed ammonium sulfate fractions from C-mutant infected cells to provide B gene function.
• Isolated and purified the omega complex for functional analysis.

Main Results:

• An extract from B-mutant infected cells synthesized infectious phage when complemented with a fraction containing the omega complex.
• The purified omega complex, containing B protein, drove viral DNA synthesis and encapsidation in the B-mutant extract.
• The intact omega complex, not just B protein alone, was essential for complementing the B-mutant extract.

Conclusions:

• The omega complex is identified as the bacteriophage phi X174 prohead.
• B protein is a crucial component of the prohead, likely serving a scaffolding function during morphogenesis.
• This finding elucidates a key step in the assembly of infectious bacteriophage particles.