Conformational Changes in Ff Phage Protein gVp upon Complexation with Its Viral Single-Stranded DNA Revealed Using...

Area of Science:

• Molecular Biology
• Structural Biology
• Virology

Background:

• Gene V protein (gVp) from Ff family bacteriophages is a key player in viral DNA replication.
• gVp functions as a non-specific single-stranded DNA (ssDNA) binding protein within host *Escherichia coli*.
• The protein is known to exist as a dimer in various states.

Purpose of the Study:

• To elucidate the structural characteristics of gVp when bound to viral ssDNA.
• To understand the molecular interactions between gVp and ssDNA.
• To investigate conformational changes in gVp upon DNA complexation.

Main Methods:

• Computational docking of free gVp to ssDNA segments.
• Solution-based detection of DNA-binding residues.
• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy for characterizing the gVp-ssDNA complex.

Main Results:

• A structural model of the gVp-ssDNA complex was generated.
• The average distance between protein residues and the DNA phosphate backbone was determined to be 5.5 Å.
• Significant protein structural changes were observed, particularly in the ssDNA binding loop and C-terminus, upon complexation.

Conclusions:

• The structure of gVp bound to ssDNA differs substantially from its free form.
• These structural alterations are likely crucial for the cooperative binding of gVp dimers.
• This cooperative binding is essential for the formation of filamentous phage particles.