Effect of bile on the cell surface permeability barrier and efflux system of Vibrio cholerae
Effect of bile on the cell surface permeability barrier and efflux system of Vibrio cholerae
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DOI：
10.1128/jb.186.20.6809-6814.2004
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发表时间：
2004-10-01
影响因子：
3.2
通讯作者：
Chowdhury, R
中科院分区：
文献类型：
--
作者：
Chatterjee, A;Chaudhuri, S;Chowdhury, R
由于外膜和能量依赖外排系统施加的渗透性屏障的协同作用，革兰氏阴性菌天生不渗透疏水化合物。革兰氏阴性肠道病原体霍乱弧菌似乎缺乏这两种活性；外膜不是疏水渗透剂的有效屏障，可能是由于外膜外叶上存在暴露的磷脂，而且外排系统充其量只是部分活跃。当霍乱弧菌在胆汁中生长时，疏水化合物进入细胞的数量明显减少。在存在或不存在胆汁的情况下生长的细胞之间，外膜外小叶上暴露的磷脂的程度没有发现差异。然而，在存在能量解偶联剂的情况下，在存在或不存在胆汁的情况下生长的细胞之间，疏水探针的摄取是相似的，这表明能量依赖的外排过程可能参与了限制疏水渗透剂进入胆汁生长细胞的过程。事实上，在胆汁存在的情况下，流出系统对霍乱弧菌的生存至关重要。编码RND家族外排泵的acrAB在体外培养的胆汁存在的霍乱弧菌细胞和兔肠细胞中表达显著增加。
Gram-negative bacteria are inherently impermeable to hydrophobic compounds, due to the synergistic activity of the permeability barrier imposed by the outer membrane and energy dependent efflux systems. The gram-negative, enteric pathogen Vibrio cholerae appears to be deficient in both these activities; the outer membrane is not an effective barrier to hydrophobic permeants, presumably due to the presence of exposed phospholipids on the outer leaflet of the outer membrane, and efflux systems are at best only partially active. When V. cholerae was grown in the presence of bile, entry of hydrophobic compounds into the cells was significantly reduced. No difference was detected in the extent of exposed phospholipids on the outer leaflet of the outer membrane between cells grown in the presence or absence of bile. However, in the presence of energy uncouplers, uptake of hydrophobic probes was comparable between cells grown in the presence or absence of bile, indicating that energy-dependent efflux processes may be involved in restricting the entry of hydrophobic permeants into bile grown cells. Indeed, an efflux system(s) is essential for survival of V. cholerae in the presence of bile. Expression of acrAB, encoding an RND family efflux pump, was significantly increased in V. cholerae cells grown in vitro in the presence of bile and also in cells grown in rabbit intestine.