The Design And Activity Mechanism Of Anti-biofilm Peptide

The formation of biofilms causes broad adaptive changes,and biofilm bacteria are especially resistant to conventional antibiotics and to date no antimicrobials have been developed specially to treat biofilms.At present,there are many attempts to deal with biofilms,such as searching anti-biofilm peptides,synergistic antibiotics,or synergistic effects of antibacterial peptides with antibiotics.Nevertheless,these efforts have not yielded the desired results.ZXR-2 is one of the AMPs which has broad-spectrum antibacterial activity,but shows low anti-biofilm activity,especially the mature biofilm.The first step in this paper was to optimize ZXR-2 for great anti-biofilm activity among the hydrophobic moment,electric charge and sequence length of peptide.The measurements of peptide activity include the IC50 of Hela cells,MIC of E.coli and S.aureus.Finally,ZXR-2.3(FKILRFIKKLWRSLLA)was screened out with best bioactivities,and it can construct secondary structure in hydrophobic environment through a-helix,which is similar to ZXR-2.So,ZXR-2.3 targets and disrupts the integrality of cell membrane,then kills cells eventually.In this article,a completely new approach is described for synergistic experiments by using peptides that have biodegradability but different action mechanisms,that IDR-1018(VRLIVAVRIWRR-NH2)and KT2(NGVQPKYKWWKWWKKWW-NH2)were used to cooperate with ZXR-2.3 to eradicate the mature biofilm.ZXR-2.3 killed bacterial by lytic the cell membrane,and its killing activity is better than degradation.While,IDR-1018 eradicated the pro-biofilm by interacting with an extracellular signal molecule(p)ppGpp and KT2 interacts with intracellular DNA to kill cells in the mature biofilm.Because of the different mechanisms of peptides,ZXR-2.3 shows the best killing activity at low concentration,and IDR-1018 has great effect on inducing biofilm degradation.The biofilm residues,biofilms in living bacteria and biofilm thickness all are considered to analyze the results of the synergy.It demonstrates that the synergistic effect of the peptides better than the synergistic effect with the antibiotics,and the synergy between ZXR-2.3 and IDR-1018 shows the best synergistic result compared to other synergies,one peptide IDR-1018 for inducing degradation of the mature biofilm and the other peptide ZXR-2.3 for killing bacteria on the biofilm,could yield better results.It is a new approach to degrade the mature biofilm,the synergy effect of anti-biofilm peptides which show the clear activity mechanisms.This method may become a fast effective treatment of diseases caused by biofilms in clinic.Although there are many ways to combine two peptides of ZXR-2.3 and IDR-1018 into one peptide,such as the dehydration condensation connection and connection by the linker GGG,the experimental results are not ideal and further optimization experiments are needed.In this paper,we demonstrate that the synergy between two peptides that could complement the effect,one peptide for inducing degradation of the mature biofilm and the other for killing bacteria on the biofilm,could yield better results.And it can be a potential new approach to clinical treatment of biofilm-induced diseases.