摘要
【目的】研究抗菌肽BuforinⅡ的衍生物BF2-A/B与大肠杆菌基因组DNA的作用机制。【方法】琼脂糖电泳检测肽对DNA的断裂作用,凝胶阻滞实验研究肽与DNA的结合作用,圆二色谱考察结合肽后DNA结构的变化,荧光光谱分析肽与溴化乙锭竞争性嵌入DNA以及磷酸根对肽与DNA相互作用的影响。【结果】BF2-A/B不断裂基因组DNA而是结合DNA,使DNA双螺旋结构变得松散,削弱碱基对间的堆积作用,并取代EB,使EB-DNA复合体系荧光减弱。而PO43-的加入减弱了肽对DNA-EB荧光的淬灭作用。【结论】衍生肽与DNA的结合方式是先靠静电引力吸附到DNA磷酸基团上,随即插入双螺旋沟槽,嵌入碱基对间。BF2-B有更多的正电荷,更强的插入沟槽和嵌入碱基对的能力,使得其结合DNA的能力比BF2-A强。
[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.
出处
《微生物学报》
CAS
CSCD
北大核心
2010年第3期328-333,共6页
Acta Microbiologica Sinica
基金
国家自然科学基金(30871805)
高校学科创新引智计划("111"计划
B07029)~~
