Catabolite repression of the propionate catabolic genes in Escherichia coli and Salmonella enterica:: Evidence for involvement of the cyclic AMP receptor protein
Catabolite repression of the propionate catabolic genes in Escherichia coli and Salmonella enterica:: Evidence for involvement of the cyclic AMP receptor protein
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DOI：
10.1128/jb.187.8.2793-2800.2005
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发表时间：
2005-04-01
影响因子：
3.2
通讯作者：
Keasling, JD
中科院分区：
文献类型：
--
作者：
Lee, SK;Newman, JD;Keasling, JD
先前对肠道沙门氏菌鼠伤寒血清型LT 2的研究表明，prpBCDE操纵子的转录激活需要转录因子PrpR、sigma-54和IHF的功能。在这项研究中，我们发现添加葡萄糖或甘油会下调prpBCDE和prpR启动子的转录，这表明这些基因可能受到环磷酸腺苷（cAMP）-环磷酸腺苷受体蛋白（CRP）复合物的调节。在prpR和prpBCDE之间的启动子区域中的假定CRP结合位点的靶向诱变表明这些基因受CRP控制。此外，cya或crp缺陷的细胞在大肠杆菌中表现出prpR和prpBCDE的转录激活降低。这些结果表明，丙酸代谢是受全球转录调节CRP的分解代谢物阻遏，这种调节是通过控制调节基因prpR和prpBCDE操纵子本身的影响。这两个不同的启动子的调节的独特性质可能具有重要的意义，CRP依赖性的分解代谢产物抑制作用的机制，与转录激活因子的σ-54家族的成员。
Previous studies with Salmonella enterica serovar Typhimurium LT2 demonstrated that transcriptional activation of the prpBCDE operon requires the function of transcription factor PrpR, sigma-54, and IHF. In this study, we found that transcription from the prpBCDE and prpR promoters was down-regulated by the addition of glucose or glycerol, indicating that these genes may be regulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex. Targeted mutagenesis of a putative CRP-binding site in the promoter region between prpR and prpBCDE suggested that these genes are under the control of CRP. Furthermore, cells with defects in cya or crp exhibited reduced transcriptional activation of prpR and prpBCDE in Escherichia coli. These results demonstrate that propionate metabolism is subject to catabolite repression by the global transcriptional regulator CRP and that this regulation is effected through control of both the regulator gene prpR and the prpBCDE operon itself. The unique properties of the regulation of these two divergent promoters may have important implications for mechanisms of CRP-dependent catabolite repression acting in conjunction with a member of the sigma-54 family of transcriptional activators.