Mechanisms of membrane toxicity of hydrocarbons
Mechanisms of membrane toxicity of hydrocarbons
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DOI：
10.1128/mr.59.2.201-222.1995
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发表时间：
1995-06
期刊：
影响因子：
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通讯作者：
J. Sikkema;J. D. de Bont;B. Poolman
中科院分区：
文献类型：
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作者：
J. Sikkema;J. D. de Bont;B. Poolman
在过去的三十年里，微生物转化环烃的研究受到了广泛的关注。对环境污染物的降解以及微生物在化学反应催化中的应用的兴趣刺激了这一领域的研究。各种芳香族化合物、环烷烃和萜烯在不同微生物中的代谢途径已被阐明，其中几种途径的遗传学已被阐明。这些化合物对微生物的毒性在烃类的微生物降解中非常重要，但对这种毒性作用的机理研究还不多。在这篇评论中，我们提出了一般的想法来自各种报告提到的毒性作用。最重要的是，亲脂性碳氢化合物在膜脂质双层中积累，影响这些膜的结构和功能特性。由于碳氢化合物分子的积累，膜失去了其完整性，并且在几种情况下观察到质子和离子渗透性的增加。因此，发生质子动力的耗散和细胞内pH稳态的损害。除了亲脂性化合物对膜脂质部分的影响外，嵌入膜中的蛋白质也会受到影响。对膜包埋蛋白的影响可能在很大程度上是由于脂质环境的变化;然而，也观察到亲脂性化合物对膜蛋白的直接影响。最后，膜脂质组成的变化，修改外膜脂多糖，改变细胞壁成分，并在减少亲脂性化合物的膜浓度的活性排泄系统的有效性进行了讨论。此外，适应（例如，脂质排序的增加、脂质/蛋白质比率的改变），其补偿膜结构的改变。
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.