大肠杆菌细胞外膜渗透性与脂多糖结构的关系(英文)

The effect of the structure of lipopolysaccharide on the permeability of Escherichia coli cell membranes

细胞外膜是大肠杆菌的半透膜屏障,其主要成分是脂多糖。选取并构造共9种具有不同脂多糖结构的大肠杆菌,用于考察脂多糖结构对细胞外膜渗透性的影响。从9种菌株中提取出脂多糖和类脂A,并且用薄层层析色谱和离子源质谱来鉴定其结构。用N-苯基-1-萘胺作为荧光探针来测定细胞外膜渗透性大小。野生型大肠杆菌表现出最小的渗透性,因敲除或表达某些基因而导致脂多糖结构改变的突变株均表现出较高的渗透性。脂多糖上的磷酸基团、脂肪酸链和多糖链的改变都影响了大肠杆菌的渗透性,其中多糖链长度的改变对渗透性影响最大,其次是脂肪酸链的数目变化。实验结果表明渗透性和脂多糖的结构具有较强的相关性。

Lipopolysaccharide is the main component of outer membranes, which serve as a permeability barrier. In this study, we investigated the role of the structure of lipopolysaccharide on the permeability of bacterial cell membranes. Nine Escherichia coli strains which make different structures of LPS were se- lected or constructed. Lipopolysaccharide and lipid A were extracted from these strains, and their struc- tures were analyzed by using thin-layer chromatography and electrospray ionization mass spectrometry. The membrane permeability of these strains was analyzed by using N-phenyl-1-naphthylamine fluorescent probe. Wild type E. coli showed the least permeability, while mutants in which LPS structures were changed by the deletion or expression of related genes showed higher permeability. The number of phosphate groups and the acyl chains, and the length of the polysaccharide of lipopolysaccharide all affect the permeability of E. coli. The chain length of the polysaccharide has the largest effect on the permeability, followed by the number of the acyl chains. The results indicate that the cellular membrane permeability is related to the structure of lipopolysaccharide.