Bacteriophage P1 protein Icd inhibits bacterial division by targeting FtsZ

The study of bacteriophage (phage) gene products and their effects on the host helps to better understand the phage-host relationship and provides clues for the development of new antimicrobial proteins. In this study, we focused on a small protein named Icd with 73 amino acids from phage P1. It inhibits the growth of <i>Escherichia coli</i> and rapidly blocks the formation of Z-ring. The results of bacterial two-hybrid and pull-down experiments showed that Icd directly targets FtsZ, a key protein in bacterial division. Furthermore, we identified the core region of Icd as amino acids 12-51; this 40-amino acid protein had similar antibacterial activity to the full-length Icd, inhibiting bacterial growth and division.