The action mechanism of analogues of the antimicrobial peptide Buforin Ⅱ with E.coli genomic DNA

Abstract:

Abstract: [Objective] The aim was to study the action mechanism of analogues BF2-A/B of the antimicrobial peptide BuforinⅡ with Escherichia coli (E.coli) genomic DNA. [Methods] The abruption and binding action of peptides to DNA were investigated by agarose electrophoresis and gel retardation assay, respectively. The change of DNA structure after binding with peptides was researched by circular dichroism spectra. The competitive intercalation of peptides and ethidium bromide (EB) into DNA, and the influence of phosphate anion to the interaction between peptides and DNA were analyzed by fluorescence spectra. [Results] BF2-A/B didn’t breakdown the genomic DNA, but they bond to DNA. Both peptides made the two-helical structure of DNA loose, and impaired the accumulation amongst base pairs. BF2-A/B could weaken the fluorescence intensity of EB-DNA complex, which appeared to inhibit the intercalation of EB into DNA. However, the addition of phosphate anion impaired the fluorescent quenching of peptides to DNA-EB complex. [Conclusion] The initial step of peptides binding to DNA was the adhesion of basic amino acid on phosphate group depended on electrostatic attraction. Then the peptides inserted the groove of DNA duplex. The direct intercalation involving phenylalanine and nucleic acid bases participate in the peptides-DNA interaction. The stronger binding affinity of BF2-B than BF2-A attributed to more positive charge and powerful ability of intercalation into groove and base pair of DNA.

Key words:Keywords: antimicrobial peptide; BuforinⅡ; E.coli; genomic DNA; action mechanism