Identification Of New Dermaseptins With Self-Assembly Tendency:Membrane Disruption,Biofilm Eradication And Infected Wound Healing Efficacy

Since the discovery of penicillin,bacteria in infections are no longer an incurable disease.However,resistant strains were gradually isolated from hospital-infected patients as the abuse of antibiotics.With the emergence of bacterial resistance,the varieties of antibiotics are greatly reduced,resulting in increased difficulty in clinical treatment.Therefore,new antibiotic candidates are urgent to discover and apply in the clinical treatment.Antimicrobial peptides(AMPs)as promising antimicrobial active chemicals with huge potential,which generally encoded by genes and synthesized by ribosomes,are mainly produced by the innate immune of host defense system and are an important effector molecule of innate immunity.Natural AMPs have a wide antimicrobial spectrum especially against multi-drug resistant bacteria,and regulate the host immune system and neutralize the harmful inflammatory response to infection.Therefore,antimicrobial peptides have become the focus of research and expect to become a new strategy to get rid of against the"drug-resistant bacteria crisis by the development and utilization of natural biological antimicrobial peptides.In this study,molecular cloning was utilized to acquire the primary structure meanwhile gene homology by comparing with NCBI database.Furthermore,mass spectrometry was used to identify the posttranslational modification.In addition,physical and chemical properties of peptide sequence were predicted by computer stimulation and the secondary structure was simulated by computer and determined by circular dichroism.The results revealed that we discovered a novel conserved dermaseptin-family nature peptide with C-terminal amidation modification,named dermaseptin-PS2(DMS-PS2).The secondary structure of DMS-PS2 is a typical a-helical structure with 4 overall cationic charge and containing 37.4% hydrophobicity.Previous studieshave published that dermaseptin family antimicrobial peptides displayed inhibitory effect on microorganisms,including gram-positive bacteria,gram-negative bacteria and fungi.In this study,broth dilution method was used to determine the antibacterial activity and anti-biofilm activity of DMS-PS2.Although DMS-PS2 showed moderate hemolysis toxicity in the experiment,considering its high therapeutic index and good therapeutic activity in vivo,DMS-PS2 has still the potential to be a lead drug for the next generation of antibiotics.The actions of many natural antimicrobial peptides are to affect bacterial plasma membrane.In this study,fluorescence staining and scanning electron microscopy were used to discover the actions of DMS-PS2.The integrity of bacterial plasma membrane was damaged after treatment with DMS-PS2,resulting in bacterial death.Additionally,the aggregation of DMS-PS2 was detected by dynamic light scattering,particle size change,atomic force microscope and computer software-assisted simulation.DMS-PS2 could self-polymerized under physiological conditions,while the oligomer of spherical DMS-PS2 had obvious antibacterial activity.