Surface-conjugated antimicrobial peptide leucocin a displays high binding to pathogenic gram-positive bacteria

Leucocin A, a representative class IIa bacteriocin, is a ribosomally synthesized antimicrobial peptide (AMP) that displays potent activity against specific gram-positive bacteria. The antibacterial activity of such peptides is preceded by the binding event that can be utilized for studying specific peptide-bacteria interactions. In this study, 37-residue Leucocin A (LeuA) was synthesized using solid-phase peptide synthesis and covalently immobilized on gold substrates from either the N- or C-terminal. Both the peptide monolayers on gold substrates were incubated separately with five strains of gram-positive bacteria and displayed differential binding to different strains with highest binding to pathogenic Listeria monocytogenes. The C-terminally immobilized LeuA showed higher bacterial binding compared to the N-terminally attached LeuA. The full length immobilized LeuA (37-residue) was active as well as displayed higher bacterial binding (73 ± 6 bacteria/100 μm²) compared to 24-residue inactive LeuA fragment (40 ± 8 bacteria/100 μm²) from the C-terminal region. The high and specific bacterial binding ability of LeuA functionalized surfaces support the potential use of class IIa bacteriocins in antimicrobial peptide-based diagnostic platforms.