Two analogues of the antimicrobial peptide buforinⅡ inhibit bacterial macromolecular synthesis in Escherichia coli

Abstract:

[Objective] In this paper, the influence to bacteria intracellular macromolecular biosynthesis after antimicrobial peptides BF2-A and BF2-B, two analogues of buforin Ⅱ, interacted with E. coli had been researched. [Methods] The influence of peptides on the synthesis of bacterial DNA and RNA had been determined by ultraviolet spectrophotometry. The influence of peptides on the synthesis of bacterial total protein had been determined by Coomassie brilliant blue method. Inhibition of β-galactosidase and alkaline phosphatase activities of E. coli cells by antibacterial peptides had been measured by ONPG and PNPP, respectively. [Results] Peptides didn’t primarily influence the synthesis of DNA and there was a lag phase. Thus the preferential inhibition of biosynthesis of RNA and protein appeared to be the primary target of BF2-A/B and the effect of the peptides on DNA-synthesis appeared to be secondary. On the same concentration, BF2-B caused a more marked inhibition of RNA-synthesis than BF2-A. Interestingly, BF2-A induced a more remarkable inhibition of protein synthesis than BF2-B. The results of activity measuring of two endocellular enzymes, β-galactosidase and alkaline phosphatase, further proved that the biosynthesis of protein was inhibited. [Conclusion] Both peptides binding to nucleic acid didn’t primarily inhibit the replication function of DNA, but primarily inhibit the transcription function of gene. Moreover, the preferential inhibition of protein-synthesis mostly embodied at the translation level.