Protein-protein interactions during filamentous phage assembly

Area of Science:

• Virology
• Molecular Biology
• Protein Interactions

Background:

• Filamentous phage assembly involves morphogenetic proteins pI and pIV.
• These proteins are crucial for phage morphogenesis but are not incorporated into the virion.
• Homologous proteins from related phages (f1 and IKe) are not interchangeable.

Purpose of the Study:

• To investigate the interaction between filamentous phage proteins pI and pIV.
• To elucidate the roles of pI and pIV in heterologous phage assembly.
• To identify other phage proteins involved in these interactions.

Main Methods:

• Genetic analysis of temperature-sensitive mutants.
• Selection for revertants and suppressor mutations.
• Isolation and characterization of phage mutants with altered protein interactions.

Main Results:

• Partial restoration of heterologous phage assembly when pI and pIV are supplied as pairs.
• Identification of an allele-specific suppressor mutation in gene I, supporting pI-pIV interaction.
• Isolation of a mutant phage with a gene VIII mutation, indicating pI interacts with the major coat protein pVIII.

Conclusions:

• Filamentous phage assembly involves specific protein-protein interactions, particularly between pI, pIV, and pVIII.
• These interactions are critical for the concomitant assembly and secretion of phage particles.
• The process is amenable to genetic dissection.