Chatterjee J, Miyamoto C M, Meighen E A
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
Mol Microbiol. 1996 Apr;20(2):415-25. doi: 10.1111/j.1365-2958.1996.tb02628.x.
Mobility-shift assays have been used to demonstrate that the activator of the Vibrio harveyi lux operon, LuxR, binds independently, and with similar affinity, to two sites upstream of its own open reading frame. One site was located between 52 and 107 bp upstream of, and the other site in a region 25 bp downstream of, the transcriptional start site. The luxR promoter, in a transcriptional fusion with the chloramphenicol acetyl transferase (cat) gene, could readily be expressed in Escherichia coli as well as V. harveyi in the absence of LuxR. In both species, the presence of the luxR gene product resulted in repression of luxR promotion. These results show that LuxR directly regulates its own expression by functioning as an autorepressor. A mechanism for this repression is suggested by evidence showing that LuxR has a negative effect on RNA polymerase binding to the luxR promoter. In light of the fact that LuxR is also part of a regulatory family of repressors, the mechanism by which LuxR functions as a transcriptional activator of the lux operon has been re-examined.
迁移率变动分析已被用于证明哈维氏弧菌lux操纵子的激活剂LuxR独立地且以相似的亲和力结合到其自身开放阅读框上游的两个位点。一个位点位于转录起始位点上游52至107 bp之间，另一个位点位于转录起始位点下游25 bp的区域。与氯霉素乙酰转移酶（cat）基因进行转录融合的luxR启动子，在没有LuxR的情况下，很容易在大肠杆菌和哈维氏弧菌中表达。在这两个物种中，luxR基因产物的存在导致luxR启动子的抑制。这些结果表明，LuxR通过作为自身抑制因子直接调节其自身的表达。有证据表明LuxR对RNA聚合酶结合到luxR启动子有负面影响，这提示了这种抑制的机制。鉴于LuxR也是一个抑制因子调节家族的一部分，LuxR作为lux操纵子转录激活剂的作用机制已被重新审视。
