Sacco M, Ricca E, Marasco R, Paradiso R, De Felice M
International Institute of Genetics and Biophysics, CNR, Naples, Italy.
FEMS Microbiol Lett. 1993 Mar 1;107(2-3):331-6. doi: 10.1111/j.1574-6968.1993.tb06053.x.
The leucine-responsive regulatory protein (Lrp) is a DNA binding protein that affects, either positively or negatively, the expression of several E. coli genes. The ilvIH operon is positively regulated by Lrp and leucine counteracts this effect reducing 5- to 10-fold the efficiency of ilvIH transcription. An investigation of the mechanism of transcription activation of the ilvIH operon by Lrp indicated that: (i) a stereospecific alignment between the ilvIH promoter and the cis-acting sequence upstream of it is required for activation; (ii) a correct distance between the promoter and the adjacent cis-acting sequence is needed for leucine to counteract the positive role of Lrp; (iii) Lrp fails to activate transcription when the cis-acting region is placed several hundred base pairs upstream of the ilvIH promoter.
亮氨酸应答调节蛋白（Lrp）是一种DNA结合蛋白，它对几种大肠杆菌基因的表达有正向或负向影响。ilvIH操纵子受Lrp正向调控，亮氨酸可抵消这种作用，使ilvIH转录效率降低5至10倍。对Lrp激活ilvIH操纵子转录机制的研究表明：（i）ilvIH启动子与其上游顺式作用序列之间的立体特异性排列是激活所必需的；（ii）启动子与相邻顺式作用序列之间需要有正确的距离，亮氨酸才能抵消Lrp的正向作用；（iii）当顺式作用区域位于ilvIH启动子上游数百个碱基对处时，Lrp无法激活转录。
