Hao Yue, Updegrove Taylor B, Livingston Natasha N, Storz Gisela
Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-5430, USA.
Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-5430, USA
Nucleic Acids Res. 2016 Aug 19;44(14):6935-48. doi: 10.1093/nar/gkw404. Epub 2016 May 10.
Here, we report the characterization of a set of small, regulatory RNAs (sRNAs) expressed from an Escherichia coli locus we have denoted sdsN located adjacent to the LuxR-homolog gene sdiA Two longer sRNAs, SdsN137 and SdsN178 are transcribed from two σ(S)-dependent promoters but share the same terminator. Low temperature, rich nitrogen sources and the Crl and NarP transcription factors differentially affect the levels of the SdsN transcripts. Whole genome expression analysis after pulse overexpression of SdsN137 and assays of lacZ fusions revealed that the SdsN137 directly represses the synthesis of the nitroreductase NfsA, which catalyzes the reduction of the nitrogroup (NO2) in nitroaromatic compounds and the flavohemoglobin HmpA, which has aerobic nitric oxide (NO) dioxygenase activity. Consistent with this regulation, SdsN137 confers resistance to nitrofurans. In addition, SdsN137 negatively regulates synthesis of NarP. Interestingly, SdsN178 is defective at regulating the above targets due to unusual binding to the Hfq protein, but cleavage leads to a shorter form, SdsN124, able to repress nfsA and hmpA.
在此，我们报道了一组小的调控RNA（sRNA）的特征，这些sRNA由大肠杆菌中一个我们命名为sdsN的基因座表达，该基因座位于LuxR同源基因sdiA附近。两个较长的sRNA，即SdsN137和SdsN178，从两个依赖于σ(S)的启动子转录，但共享相同的终止子。低温、丰富的氮源以及Crl和NarP转录因子对SdsN转录本的水平有不同影响。在SdsN137脉冲过表达后的全基因组表达分析以及lacZ融合分析表明，SdsN137直接抑制硝基还原酶NfsA的合成，NfsA催化硝基芳香族化合物中硝基（NO2）的还原，以及黄素血红蛋白HmpA的合成，HmpA具有有氧一氧化氮（NO）双加氧酶活性。与这种调控一致，SdsN137赋予对硝基呋喃的抗性。此外，SdsN137负向调节NarP的合成。有趣的是，SdsN178由于与Hfq蛋白的异常结合而在调控上述靶标方面存在缺陷，但切割会产生一种较短的形式SdsN124，它能够抑制nfsA和hmpA。
