RutR is the uracil/thymine-sensing master regulator of a set of genes for synthesis and degradation of pyrimidines
RutR is the uracil/thymine-sensing master regulator of a set of genes for synthesis and degradation of pyrimidines
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DOI：
10.1111/j.1365-2958.2007.05954.x
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Ishihama, Akira
中科院分区：
文献类型：
--
作者：
Shimada, Tomohiro;Hirao, Kiyo;Ishihama, Akira
使用基因组SELEX，共鉴定了6个大肠杆菌DNA片段，它们与转录因子RutR形成复合物。发现RutR调节子包括大量编码不仅用于嘧啶降解而且用于谷氨酸转运、谷氨酰胺合成、嘧啶核苷酸和精氨酸合成以及嘌呤降解的组分的基因。DNA酶I足迹法表明RutR识别TTGACCAnTGGTCAA的回文序列。carAB基因P1启动子中的RutR盒与PepA（Carp）阻遏物结合位点重叠，提示RutR与PepA之间存在竞争。添加尿嘧啶或胸腺嘧啶在体外消除RutR与carAB PI启动子的结合。因此，在rutR缺失突变体中或在尿嘧啶存在下，carAB P1启动子的体内活化显著降低。RutR靶基因的北方印迹分析表明，RutR抑制Gad系统基因参与谷氨酸依赖性耐酸性和尿囊素降解。总之，我们建议，RutR是嘧啶传感器和主调节器的一个大的基因参与嘧啶的合成和降解。
Using the genomic SELEX, a total of six Escherichia coli DNA fragments have been identified, which formed complexes with transcription factor RutR. The RutR regulon was found to include a large number of genes encoding components for not only degradation of pyrimidines but also transport of glutamate, synthesis of glutamine, synthesis of pyrimidine nucleotides and arginine, and degradation of purines. DNase I footprinting indicated that RutR recognizes a palindromic sequence of TTGACCAnnTGGTCAA. The RutR box in P1 promoter of carAB encoding carbamoyl phosphate synthetase, a key enzyme of pyrimidine synthesis, overlaps with the PepA (Carp) repressor binding site, implying competition between RutR and PepA. Adding either uracil or thymine abolished RutR binding in vitro to the carAB PI promoter. Accordingly, in the rutR-deletion mutant or in the presence of uracil, the activation in vivo of carAB P1 promoter was markedly reduced. Northern blot analysis of the RutR target genes indicated that RutR represses the Gad system genes involved in glutamate-dependent acid resistance and allantoin degradation. Altogether we propose that RutR is the pyrimidine sensor and the master regulator for a large set of the genes involved in the synthesis and degradation of pyrimidines.