CONTROL OF VIBRIO-FISCHERI LUX GENE-TRANSCRIPTION BY A CYCLIC-AMP RECEPTOR PROTEIN LUXR PROTEIN REGULATORY CIRCUIT
CONTROL OF VIBRIO-FISCHERI LUX GENE-TRANSCRIPTION BY A CYCLIC-AMP RECEPTOR PROTEIN LUXR PROTEIN REGULATORY CIRCUIT
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DOI：
10.1128/jb.170.9.4040-4046.1988
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发表时间：
1988-09-01
影响因子：
3.2
通讯作者：
GREENBERG, EP
中科院分区：
文献类型：
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作者：
DUNLAP, PV;GREENBERG, EP
费氏弧菌发光基因（lux 基因）的表达需要两种转录激活剂：带有自诱导剂的费氏弧菌 luxR 基因产物和带有 cAMP 的环 AMP (cAMP) 受体蛋白 (CRP)。已经确定，luxICDABE操纵子的转录激活需要自诱导剂和luxR基因产物，该操纵子包含自诱导剂合成所需的基因和光发射所需的基因。然而，cAMP-CRP 在发光诱导中的作用尚不清楚。我们使用携带含有 lux DNA 的质粒的分解代谢抑制突变体检查了大肠杆菌中 lux 基因的转录控制。 Mu dI 和 luxR 上 lacZ 基因之间的转录融合用于评估 luxR 启动子活性，而 luxAB 基因（编码两个荧光素酶亚基）用作 luxICDABE 启动子活性的天然报告基因。构建了包含在 cAMP CRP 独立的 tac 启动子控制下的 luxR 的质粒，以指导在包含相容 luxR::Mu dI 插入突变体质粒的细胞中合成 luxR 基因产物。在大肠杆菌中，cAMP-CRP 激活 luxR 的转录，同时减少 luxICDABE 的转录。在存在相对高水平的 luxR 基因产物的情况下，诱导 luxICDABE 操纵子不需要 cAMP 和 CRP。如前所述，在自诱导剂存在的情况下，luxR 基因产物激活 luxICDABE 操纵子的转录，并且我们证明它还减少了 luxR 转录。显然，V. fischeri 发光基因的控制涉及一个调节电路，其中 cAMP 和 CRP 激活 luxR 转录，反过来 luxR 基因产物激活负责发光的操纵子 (luxICDABE) 的转录。此外，在 lux 基因调控中，cAMP-CRP 和自诱导剂-LuxR 蛋白似乎起到转录拮抗剂的作用。
Expression of the Vibrio fischeri luminescence genes (lux genes) requires two transcriptional activators: the V. fischeri luxR gene product with autoinducer and the cyclic AMP (cAMP) receptor protein (CRP) with cAMP. It has been established that autoinducer and the luxR gene product are required for transcriptional activation of the luxICDABE operon, which contains a gene required for autoinducer synthesis and genes required for light emission. However, the role of cAMP-CRP in the induction of luminescence is not clear. We examined transcriptional control of the lux genes in Escherichia coli, using catabolite repression mutants carrying lux DNA -containing plasmids. Transcriptional fusions between the lacZ gene on Mu dI and luxR were used to assess luxR promoter activity, and the luxAB genes (which encode the two luciferase subunits) were used as a natural reporter of luxICDABE promoter activity. A plasmid containing luxR under control of the cAMP CRP-independent tac promoter was constructed to direct the synthesis of the luxR gene product in cells containing compatible luxR::Mu dI insertion mutant plasmids. In E. coli, cAMP-CRP activated transcription of luxR and concurrently decreased luxICDABE transcription. In the presence of relatively high levels of the luxR gene product, cAMP and CRP were not required for induction of the luxICDABE operon. The luxR gene product in the presence of autoinducer activated transcription of the luxICDABE operon, as has been shown previously, and we demonstrate that it also decreased luxR transcription. Apparently, control of the V. fischeri luminescences genes involves a regulatory circuit in which cAMP and CRP activate luxR transcription and in turn the luxR gene product activates transcription of the operon responsible for light emission (luxICDABE). Furthermore, in lux gene regulation cAMP-CRP and autoinducer-LuxR protein appear to function as transcriptional antagonists.