Dixon R
Mol Gen Genet. 1986 Apr;203(1):129-36. doi: 10.1007/BF00330393.
The xylABC promoter (OP1), located on the TOL plasmid of Pseudomonas putida contains sequences homologous to the conserved regions found in nitrogen fixation (nif) promoters and in other promoters subject to nitrogen control. XylA-lac fusions were constructed in order to monitor expression from the OP1 promoter in Escherichia coli. Transcription was activated in the presence of the heterologous regulatory genes ntrC or nifA from Klebsiella pneumoniae as well as by the homologous P. putida regulatory gene xylR. In all cases activation was also dependent on the ntrA gene, whose product has been implicated as a specific sigma factor for ntr activatable operons. The 5' ends of xylA mRNA, detected by S1 nuclease mapping of in vivo transcripts, were identical in strains containing xylR, ntrC or nifA as transcriptional activators. However, activation of the K. pneumoniae nifL or nifH promoters by xylR was not detected.
恶臭假单胞菌TOL质粒上的木糖ABC启动子（OP1）含有与固氮（nif）启动子及其他受氮控制的启动子中发现的保守区域同源的序列。构建了木糖A-乳糖融合体，以监测大肠杆菌中OP1启动子的表达。在存在肺炎克雷伯菌的异源调控基因ntrC或nifA以及恶臭假单胞菌同源调控基因木糖R的情况下，转录被激活。在所有情况下，激活也依赖于ntrA基因，其产物被认为是ntr可激活操纵子的特异性σ因子。通过对体内转录本进行S1核酸酶作图检测到的木糖A mRNA的5′末端，在含有木糖R、ntrC或nifA作为转录激活因子的菌株中是相同的。然而，未检测到木糖R对肺炎克雷伯菌nifL或nifH启动子的激活。
