Transcriptional Regulation of Membrane Lipid Homeostasis in Escherichia coli*
Transcriptional Regulation of Membrane Lipid Homeostasis in Escherichia coli*
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DOI：
10.1074/jbc.m109.068239
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发表时间：
2009-10
期刊：
影响因子：
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通讯作者：
Kun Zhu;Yong-mei Zhang;C. Rock
中科院分区：
文献类型：
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作者：
Kun Zhu;Yong-mei Zhang;C. Rock
膜磷脂的生物物理特性由其组成脂肪酸的组成控制，并在大肠杆菌中受到严格调节。 FabR（脂肪酸生物合成阻遏蛋白）转录阻遏蛋白通过调节 fabB（β-酮酰基-ACP 合成酶 I）和 fabA（β-羟基癸酰基-ACP 脱水酶/异构酶）基因的表达来控制膜中不饱和脂肪酸的比例。 FabR 与位于 fabB 和 fabA 基因启动子内的 DNA 回文结构的结合需要不饱和酰基-酰基载体蛋白 (ACP) 或酰基-CoA 的存在，并被饱和酰基-ACP 或酰基-CoA 拮抗。外源不饱和脂肪酸对 fabB 和 fabA 的 FabR 依赖性抑制证实了 FabR 在响应酰基辅酶 A 池组成中的作用，并且使用脂质 A 形成的特异性抑制剂对不饱和：饱和酰基 -ACP 比例的扰动证实了体内酰基 -ACP 成分对 fabB 的 FabR 依赖性调节。因此，FabR 通过响应长链酰基硫酯池的组成调节基因表达，在控制膜生物物理特性方面发挥着关键作用。这种机制确保脂肪酸的平衡组成可通过 PlsB/PlsC 酰基转移酶掺入膜中。
The biophysical properties of membrane phospholipids are controlled by the composition of their constituent fatty acids and are tightly regulated in Escherichia coli. The FabR (fatty acid biosynthesis repressor) transcriptional repressor controls the proportion of unsaturated fatty acids in the membrane by regulating the expression of the fabB (β-ketoacyl-ACP synthase I) and fabA (β-hydroxydecanoyl-ACP dehydratase/isomerase) genes. FabR binding to a DNA palindrome located within the promoters of the fabB and fabA genes required the presence of an unsaturated acyl-acyl carrier protein (ACP) or acyl-CoA and was antagonized by saturated acyl-ACP or acyl-CoA. The FabR-dependent repression of fabB and fabA by exogenous unsaturated fatty acids confirmed the role for FabR in responding to the acyl-CoA pool composition, and the perturbation of the unsaturated:saturated acyl-ACP ratio using a specific inhibitor of lipid A formation verified FabR-dependent regulation of fabB by the acyl-ACP composition in vivo. Thus, FabR plays a key role in controlling the membrane biophysical properties by regulating gene expression in response to the composition of the long-chain acyl-thioester pool. This mechanism ensures that a balanced composition of fatty acids is available for incorporation into the membrane via the PlsB/PlsC acyltransferases.