YtxR, a conserved LysR-like regulator that induces expression of genes encoding a putative ADP-ribosyltransferase toxin homologue in Yersinia enterocolitica
YtxR, a conserved LysR-like regulator that induces expression of genes encoding a putative ADP-ribosyltransferase toxin homologue in Yersinia enterocolitica
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DOI：
10.1128/jb.01159-06
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发表时间：
2006-12-01
影响因子：
3.2
通讯作者：
Darwin, Andrew J.
中科院分区：
文献类型：
--
作者：
Axler-DiPerte, Grace L.;Miller, Virginia L.;Darwin, Andrew J.
小肠结肠炎耶尔森氏菌引起人类胃肠炎，许多分离株根据其地理流行率和毒力特性被分类为“美国”或“非美国”菌株。在这项研究中，我们描述了一个转录调控因子，控制表达的Y。小肠结肠炎菌ytxAB基因。ytxAB基因具有编码与百日咳毒素相似的ADP-核糖基化毒素的潜力。然而，ytxAB无效突变不影响小鼠的毒力。然而，ytxAB基因在许多Y.小肠结肠炎菌株。有趣的是，美国和非美国菌株具有不同的ytxAB等位基因，编码的蛋白质只有50%至60%相同。为了进一步了解ytxAB基因座，我们研究了它是否作为已知或新型调节子的一部分进行调节。转座子诱变鉴定了LysR样调节因子，我们将其命名为YtxR。从标准启动子表达ytrR使phi（ytxA-lacZ）操纵子融合表达增加高达35倍。YtxR还激活其自身启动子的表达。DNA酶I足迹法显示，HiS（6）-YtxR融合蛋白直接与ytxA和ytxR控制区在其可能的转录起始位点上游的相似距离处相互作用，通过引物延伸鉴定。缺失分析表明，在体外去除His（6）-YtxR保护的区域消除了体内YtxR依赖性诱导。ytxAB基因座不存在于大多数耶尔森氏菌物种中。相比之下，ytrR在多个耶尔森氏菌属物种中是保守的，以及在密切相关的生物发光杆菌和不对称发光杆菌中。这些观察结果表明，YtxR可能发挥保守的作用，涉及调控其他基因除了ytxAB。
Yersinia enterocolitica causes human gastroenteritis, and many isolates have been classified as either "American" or "non-American" strains based on their geographic prevalence and virulence properties. In this study we describe identification of a transcriptional regulator that controls expression of the Y. enterocolitica ytxAB genes. The ytxAB genes have the potential to encode an ADP-ribosylating toxin with similarity to pertussis toxin. However, a ytxAB null mutation did not affect virulence in mice. Nevertheless, the ytxAB genes are conserved in many Y. enterocolitica strains. Interestingly, American and non-American strains have different ytxAB alleles encoding proteins that are only 50 to 60% identical. To obtain further insight into the ytxAB locus, we investigated whether it is regulated as part of a known or novel regulon. Transposon mutagenesis identified a LysR-like regulator, which we designated YtxR, Expression of ytrR from a normative promoter increased phi(ytxA-lacZ) operon fusion expression up to 35-fold. YtxR also activated expression of its own promoter. DNase I footprinting showed that a HiS(6)-YtxR fusion protein directly interacted with the ytxA and ytxR control regions at similar distances upstream of their probable transcription initiation sites, identified by primer extension. Deletion analysis demonstrated that removal of the regions protected by His(6)-YtxR in vitro eliminated YtxR-dependent induction in vivo. The ytxAB locus is not present in most Yersinia species. In contrast, ytrR is conserved in multiple Yersinia species, as well as in the closely related organisms Photorhabdus luminescens and Photorhabdus asymbiotica. These observations suggest that YtxR may play a conserved role involving regulation of other genes besides ytxAB.