Copper-binding Motifs Xxx-His or Xxx-Zzz-His (ATCUN) Linked to an Antimicrobial Peptide: Cu-binding, Antimicrobial Activity and ROS Production

Depending on the coordination, copper ions can have a very high activity in catalyzing the production of reactive oxygen species. Thus interest arose in increasing the activity of antimicrobial peptides (AMPs) by equipping them with a Cu-binding unit. Several examples, native and engineered, have been investigated with the motif Xxx-Zzz-His, called Amino Terminal Cu(II)- and Ni(II)-binding (ATCUN) motif. Here we investigate a short AMP that was equipped either with Xxx-Zzz-His or Xxx-His. Xxx-His is a shorter motif and yields a more redox active copper complex. The control AMP, Xxx-His-AMP and Xxx-Zzz-His-AMP were investigated toward Cu-binding, Reactive Oxygen Species (ROS) production and antimicrobial activity in E. coli. The data indicate that these Cu-binding motifs have very limited impact on antimicrobial activity and low ROS production capability.