近日，国际著名杂志Gene在线刊登了韩国釜山国立大学研究人员的最新研究成果“AntR-mediated bidirectional activation of antA and antR，anthranilate degradative genes in Pseudomonas aeruginosa”，文章中，研究者揭示了转录调节因子AntR的双向激活基因的作用。
双向转录激活作用是基因表达的一种特定模式。在细菌中，转录调节作用可以被转录因子双向调节，比如铜绿假单胞菌的群体感应系统调节子LasR和QscR，可以在结合到单一位点来同时激活两个分开的基因进行双向表达。
在这篇研究文章中， 作者Joon-Hee Lee揭示了邻氨基苯甲酸盐代谢相关转录激活子AntR可以对别的基因进行双向转录调节的作用。
在铜绿假单胞菌中（P.aeruginosa）中，antABC操纵子和基因antR分别位于染色体的不同位置（不相邻，分开的），研究者为了更好地理解AntR对antABC的转录调节作用，他们绘制了转录起始位点以及AntR的转录调节元件antAp。通过研究，研究者发现AntR可以激活两个分开的基因，antA和antR，而且在antA和antR基因的间隔区域存在两个AntR的效应元件AREs(AntR responsive elements)。因此，研究者表示这两个AREs对于AntR有不同的亲和力，而且对于不对称地双向激活基因antA和antR的表达至关重要。（生物谷：T.Shen编译）
doi:10.1016/j.gene.2012.05.004
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AntR-mediatedbidirectionalactivation of antA and antR, anthranilatedegradativegenes in Pseudomonasaeruginosa
Soo-Kyoung Kim1, Su-Jin Im1, Doo-Hwan Yeom, Joon-Hee Lee,
Bidirectionalactivation of transcription is a peculiar regulation mode of gene expression. In this study, we show that genes involved in the metabolism of anthranilate, a precursor of biosynthesis of tryptophan and Pseudomonas quinolone signal (PQS) are regulated by this bidirectionalactivation of transcription. Anthranilate is degraded by anthranilate dioxygenase complex encoded by antABC operon, and AntR, a LysR-type regulator encoded by antR activates the transcription of antABC operon in the presence of anthranilate. In P. aeruginosa, antABC and antR are divergently located and AntR binds to the intergenic region between antA and antR to activate the antABC transcription. In this study, we determined the transcriptional start site of the antA promoter (antAp) and AntR-responsive elements (AREs) in P. aeruginosa. The upstream deletion analysis of antAp and in vitro gel shift assay with purified AntR showed that there are two AREs at − 194 to − 148 and − 88 to − 47 regions. We also found that AntR activates antR promoter (antRp) in the opposite direction and both AREs are important in the bidirectionalactivation of antAp and antRp. Two AREs have different binding affinities to AntR and the strength of transcriptional activation was dramatically asymmetric depending on the direction. We suggest that the different affinities of two AREs may explain the asymmetry of the bidirectionalactivation by AntR.
