Structure-Antimicrobial Activity Relationships of Recombinant Host Defence Peptides Against Drug-Resistant Bacteria.

Host defence peptides (HDPs) represent a valuable class of antimicrobial agents with the potential to address the growing threat of antimicrobial resistance (AMR). Here, we have studied recombinant constructs based on a combination of HDPs fused to the GFP protein and multidomain proteins combining three or four HDPs in a single polypeptide, referred to as first and second generation antimicrobials, respectively. These recombinant peptides were tested against Gram-positive and Gram-negative bacteria associated with healthcare infections. In addition, in silico studies provided insight into the antimicrobial structure-activity relationships of these biomolecules. For the first generation of antimicrobials, amphipathicity mainly explains the average antimicrobial activity against the Gram-positive strains. In the case of the Gram-negative bacteria, it depends on the quantity and the exposed area of the Ser and Thr amino acids. For the second generation of antimicrobials, the order of domains is crucial to act against Gram-positive strains, preferably by positioning the most bioactive domain against the Gram-positive pathogen at the ends.