天蚕素A-马盖宁杂合肽对耐甲氧西林金黄色葡萄球菌抑菌机制的研究

【目的】研究天蚕素A-马盖宁杂合肽对耐甲氧西林金黄色葡萄球菌(MRSA)DNA作用的抑菌机制。【方法】利用激光扫描共聚焦显微镜(CLSM)、凝胶阻滞分析、紫外光谱分析、荧光光谱分析的方法。【结果】天蚕素A-马盖宁杂合肽对MRSA的最小抑菌浓度(MIC)为64 mg/L,杂合肽可以在细菌胞内形成累积,并能与体外基因组DNA发生结合作用。同时杂合肽可以引起DNA构象的改变,荧光光谱分析结果表明杂合肽能与溴化乙锭(EB)竞争性地嵌入基因组DNA中,作用方式类似于EB与DNA的结合方式,杂合肽与DNA的结合表现为混合式作用方式。【结论】天蚕素A-马盖宁进入细菌胞内,与MRSA基因组DNA结合,并以混合式作用方式与DNA发生了结合,通过胞内靶向机制发挥抑菌作用。

Inhibition of MRSA by hybrid peptides of CecropinA-Magainins

Objective] To investigate the antimicrobial mechanism of DNA action of CecropinA-Magainins treatment on the Methicillin-resistant Staphylococcus aureus (MRSA). Methods] The mechanism was analyzed by Confocal Laser Scanning Microscope (CLSM), Gel shift Assay, Ultraviolet Spectrum Analysis and Fluorescence Spectrum Analysis. Results] The results demonstrated that the minimal inhibitory concentration (MIC) of the peptide against MRSA was 64 mg/L. The hybrid peptide could accumulate within the bacterial cell, and bind with the genomic DNA in vitro. Meanwhile, the hybrid peptide caused the change of DNA conformation. The results of Fluorescence Spectrum Analysis showed that the hybrid peptide competitively embedded genomic DNA with EB, and its combination mode was similar to the mode of EB and DNA. Finally, we found the combination mode of hybrid peptide and DNA was mixed mode. Conclusion] CecropinA-Magainins can enter into the bacterial cell, bind with the genomic DNA. The hybrid peptide kills bacteria via intracellular-targeting mechanism.