Antimicrobial Peptide CRAMP (16-33) Stalls Bacterial Cytokinesis by Inhibiting FtsZ Assembly

A cathelin-related antimicrobial peptide (CRAMP) of 37 amino acid residues is thought to regulate innate immunity and provide a host defense mechanism in mammals. Here, a part of the CRAMP peptide, CRAMP (16-33) (GEKLKKIGQKIKNFFQKL), was found to bind to FtsZ and to inhibit the assembly and GTPase activity of FtsZ in vitro. A computational analysis indicated that CRAMP (16-33) binds in the cavity of the T7 loop of FtsZ. Both hydrophobic and ionic interactions were involved in the binding interactions. Further, CRAMP (16-33) inhibited the formation of the FtsZ ring in bacteria, indicating that it inhibited bacterial cell division by inhibiting FtsZ assembly.