Thermal regulation of membrane fluidity in Escherichia coli. Effects of overproduction of beta-ketoacyl-acyl carrier protein synthase I.
Thermal regulation of membrane fluidity in Escherichia coli. Effects of overproduction of beta-ketoacyl-acyl carrier protein synthase I.
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DOI：
10.1016/s0021-9258(18)32888-6
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发表时间：
1983-02
期刊：
影响因子：
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通讯作者：
Diego de Mendoza;A. K. Ulrich;J. Cronan
中科院分区：
文献类型：
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作者：
Diego de Mendoza;A. K. Ulrich;J. Cronan
携带β-酮脂酰-酰基载体蛋白（ACP）合酶I的结构基因（fabB）的多拷贝质粒在体外构建并转化到各种大肠杆菌菌株中。将这些质粒导入fabB菌株导致fabB+表型和合成酶I活性的大量（8- 10倍）过量产生。携带这些质粒的菌株也对浅蓝菌素（一种特异性抑制β-酮脂酰-ACP合酶活性的抗生素）具有异常的耐药性，并过度产生顺式异油酸。缺乏β-酮脂酰-ACP合酶II的菌株（fabF-）在顺式异油酸合成和热调节方面都有缺陷。将fabB质粒引入这些菌株导致顺式异油酸合成的恢复。然而，这些菌株的质粒产生的顺式异油酸合成不受温度的影响。这些结果表明，合成酶II，产品的fabF基因，是唯一的酶调节温度依赖性的膜磷脂酰基链的组合物。
Multicopy plasmids bearing the structural gene (fabB) for beta-ketoacyl-acyl carrier protein (ACP) synthase I were constructed in vitro and transformed into various Escherichia coli strains. Introduction of these plasmids into fabB strains resulted in a fabB+ phenotype and a large (8- to 10-fold) overproduction of synthase I activity. Strains carrying these plasmids were also unusually resistant to cerulenin (an antibiotic that specifically inhibits beta-ketoacyl-ACP synthase activity) and overproduced cis-vaccenic acid. Strains (fabF-) lacking beta-ketoacyl-ACP synthase II are deficient in both cis-vaccenic acid synthesis and thermal regulation. Introduction of the fabB plasmids into these strains resulted in the restoration of cis-vaccenic acid synthesis. However, the plasmid-engendered cis-vaccenic acid synthesis of these strains was unaffected by temperature. These results demonstrate that synthase II, the product of the fabF gene, is the sole enzyme regulating the temperature-dependent composition of the membrane phospholipid acyl chains.