Miyamoto Carol M, Meighen Edward A
Department of Biochemistry, Room 813, McIntyre Medical Sciences Building, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada H3G 1Y6.
Biochim Biophys Acta. 2006 Jun;1759(6):296-307. doi: 10.1016/j.bbaexp.2006.05.005. Epub 2006 Jun 7.
Quorum sensing, involving signal transduction via the two-component response regulator LuxO to its downstream target LuxR, controls luminescence in the marine bacterium Vibrio harveyi. LuxR is a DNA binding protein that acts as both activator of the lux operon and repressor of its own gene. In order to determine if any other genes are affected by quorum sensing in V. harveyi, an assay for luxR-dependent promotion was devised using a genomic library maintained in a novel luxAB (luciferase) reporter. Screening in Escherichia coli DH-21 (lacI(sq)) entailed the addition of a second plasmid containing luxR under plac control. Four out of 5000 colonies showed luminescence stimulation upon IPTG induction of luxR. The four luxR-dependent promoters were upstream of argA, purM, lysE, and rluA, genes involved in arginine and purine biosyntheses, amino acid efflux, and pseudouridine synthesis, respectively. Based on analysis of luxR-dependent promoters, particularly that of argA, we describe a LuxR binding site, and implicate the coordination of LuxR with ArgR.
群体感应涉及通过双组分响应调节因子LuxO向其下游靶标LuxR的信号转导，控制海洋细菌哈氏弧菌中的发光。LuxR是一种DNA结合蛋白，既是lux操纵子的激活剂，又是其自身基因的抑制剂。为了确定哈氏弧菌中是否有任何其他基因受群体感应影响，使用保存在新型luxAB（荧光素酶）报告基因中的基因组文库设计了一种luxR依赖性促进检测方法。在大肠杆菌DH-21（lacI(sq)）中进行筛选需要添加第二个在plac控制下含有luxR的质粒。在5000个菌落中，有4个在IPTG诱导luxR后显示出发光刺激。这四个luxR依赖性启动子分别位于参与精氨酸和嘌呤生物合成、氨基酸外排和假尿苷合成的argA、purM、lysE和rluA基因的上游。基于对luxR依赖性启动子的分析，特别是argA的启动子，我们描述了一个LuxR结合位点，并暗示了LuxR与ArgR的协同作用。
