Abstract: To explore the non-cytoplasmic membrane damage antimicrobial mechanism of metal antimicrobial peptide SIF4 against foodborne Escherichia coli based on intracellular nucleic acid and protein targets, the effects of SIF4 on intracellular nucleic acid biosynthesis, the fluorescence spectrum of SIF4 and EB competitively binding genomic DNA, the UV spectrum of SIF4 interacting with genomic DNA, and the binding mode of SIF4 and genomic DNA were studied, and on intracellular protein biosynthesis were systematically studied. Results confirmed that that SIF4 could bind to E. coli genomic DNA through groove insertion and had a positive dose effect on nucleic acid biosynthesis; Fluorescence spectrum analysis of EB competitive binding DNA showed that SIF4 could competitively bind EB to genomic DNA through intercalation binding and electrostatic adsorption; UV spectroscopy showed that the combination of SIF4 with genomic DNA can change its molecular conformation, but does not break the double strand structure of genomic DNA; Circular dichroism spectroscopy showed that the stacking force of genomic DNA base was weakened, the double helix structure became loose, and the genomic DNA structure changed from B configuration to C configuration after it was combined with SIF4; SIF4 could significantly affect the intracellular protein biosynthesis, and its inhibition effect was positively correlated with the treatment time and dose of SIF4. It is believed that SIF4 can enter the DNA trench through electrostatic adsorption or intercalation with genomic DNA, and affect DNA replication, RNA transcriptional biomass and protein translation to produce non-cytoplasmic damage against Escherichia coli. All results can provide support for clarifying non-cytoplasmic membrane damage antimicrobial mechanism of metal antimicrobial peptide SIF4 against E.coli based on cytoplasmic biomacromolecules and control of food borne E. coli.

Key words: metal antimicrobial peptide, Escherichia coli, intracellular biomacromolecules, non-cytoplasmic membrane damage, antimicrobial mechanism.