PdhR (pyruvate dehydrogenase complex regulator) controls the respiratory electron transport system in Escherichia coli
PdhR (pyruvate dehydrogenase complex regulator) controls the respiratory electron transport system in Escherichia coli
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DOI：
10.1128/jb.00229-07
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发表时间：
2007-08-01
影响因子：
3.2
通讯作者：
Ishihama, Akira
中科院分区：
文献类型：
--
作者：
Ogasawara, Hiroshi;Ishida, Yuji;Ishihama, Akira
丙酮酸脱氢酶（PDH）多酶复合体在糖酵解和柠檬酸循环之间的代谢相互联系中起着关键作用。pdhR-aceEF-lpdA操纵子中PDH复合物的所有三种组分的大肠杆菌基因的转录被丙酮酸敏感PdhR（GntR家族转录调节因子）抑制，并被丙酮酸解抑制。经过系统的搜索PdhR的调节目标，使用基因组系统进化的配体指数富集（SELEX），我们已经确定了两个新的目标，ndh，编码NADH脱氢酶11，和cyoABCDE，编码细胞色素bo型氧化酶，两者一起形成的途径呼吸电子传递下游的PDH循环。PDH产生NADH，而Ndh和CyoABCDE一起将电子从NADH转移到氧气。使用凝胶移位和DNA酶I足迹分析，PdhR结合位点（PdhR盒）被定义，其包括回文共有序列ATTGGTNNACCAAT。在丙酮酸存在下，PdhR与PdhR盒的体外结合降低。使用双荧光蛋白载体的体内启动子测定也表明，新鉴定的操纵子被PdhR阻遏，并通过加入丙酮酸解阻遏。两者合计，我们建议，PdhR是一个主调节器，不仅控制PDH复合物的形成，但也呼吸电子传递系统。
The pyruvate dehydrogenase (PDH) multienzyme complex plays a key role in the metabolic interconnection between glycolysis and the citric acid cycle. Transcription of the Escherichia coli genes for all three components of the PDH complex in the pdhR-aceEF-lpdA operon is repressed by the pyruvate-sensing PdhR, a GntR family transcription regulator, and derepressed by pyruvate. After a systematic search for the regulation targets of PdhR using genomic systematic evolution of ligands by exponential enrichment (SELEX), we have identified two novel targets, ndh, encoding NADH dehydrogenase 11, and cyoABCDE, encoding the cytochrome bo-type oxidase, both together forming the pathway of respiratory electron transport downstream from the PDH cycle. PDH generates NADH, while Ndh and CyoABCDE together transport electrons from NADH to oxygen. Using gel shift and DNase I footprinting assays, the PdhR-binding site (PdhR box) was defined, which includes a palindromic consensus sequence, ATTGGTNNNACCAAT. The binding in vitro of PdhR to the PdhR box decreased in the presence of pyruvate. Promoter assays in vivo using a two-fluorescent-protein vector also indicated that the newly identified operons are repressed by PdhR and derepressed by the addition of pyruvate. Taken together, we propose that PdhR is a master regulator for controlling the formation of not only the PDH complex but also the respiratory electron transport system.