Investigating The Effect Of Proline Linkers On Hybrid Antimicrobial Peptide Structure And Activity

Antimicrobial peptides (AMPs) have been proposed as alternatives to conventional antibiotics in efforts to design more effective treatments for antibiotic resistant bacterial infections. AMPs are found in many organisms, including humans, as part of the innate immune response. One method of designing novel AMPs is to connect two individual AMPs to form a hybrid AMP. Often the individual AMPs in a hybrid are connected by a linker consisting of one or more amino acids. Previous studies have shown that some hybrid AMPs have increased antibacterial activity and reduced cytotoxicity to eukaryotic cells. However, the effects of various linkers and hybrid designs on activity have not been systematically evaluated. This study examines hybrid AMPs formed from two translocating histone-derived antimicrobial peptides (HDAPs): the naturally occurring buforin II (BF2) and the synthesized peptide DesHDAP1. Previous work in our laboratory has shown that proline linkers enhance the activity of these BF2/DesHDAP1 hybrids. Additional BF2/DesHDAP1 hybrids were designed using glycine and N-methyl alanine linkers to determine which structural feature of proline was responsible for this observed increase in antibacterial activity. Antibacterial activity and circular dichroism spectroscopy results suggest that proline's inability to hydrogen bond contributes more to antibacterial activity than physical rigidity. Molecular dynamics simulations were also performed to compare the hybrids’ structure and interactions with membranes on a molecular level. Ongoing work is investigating the activity of these BF2/DesHDAP1 hybrid AMPs against eukaryotic cells.