CRISPR-Cpf1-Mediated T4 Phage Genome Editing for One-Step In Vivo Display of Heterologous Protein

The T4 phage is a robust vector for high-density heterologous protein display. It leverages two non-essential outer capsid proteins, i.e., Soc (~870 copies) and Hoc (~155 copies). These two proteins enable the efficient display of target proteins on the capsid of T4. Here, we detail the workflow for one-step in vivo display of a heterologous protein. Specifically, this method utilizes CRISPR-Cpf1-mediated gene editing technology to insert the sequence of interest (using mCherry as an example) downstream of the Soc encoding gene within the T4 phage genome, resulting in a Soc-fused recombinant protein. This engineering method allows for endogenous expression of the Soc-mCherry recombinant protein within Escherichia coli cells during phage replication, after which the recombinant protein spontaneously assembles onto the capsid of the engineered phage. By providing a universal framework suitable for in vivo display, this approach empowers researchers to readily construct tailored T4 nanoparticles for diverse biotechnological applications.