背景:AphA是弧菌中在低细胞密度下运行的主群体感应(QS)调节剂。已在哈氏弧菌和霍乱弧菌中表征了AphA对靶基因的分子调控。但在副溶血性弧菌中仍然知之甚少。
结果:AphA蛋白在副溶血性弧菌中极为保守,弧菌sp.Ex25,Vibriosp.EJY3,V.harveyi,五、创伤,五、脾,V.anguillarum,V.霍乱弧菌,和V.furnissii。上述9个AphA直向同源物似乎识别保守的顺式作用DNA信号,这些信号可以由两个共有构建体代表。一个20bp的盒序列和一个位置频率矩阵。V.副溶血性AphA抑制ahpA的转录,qrr4和opaR通过直接AphA-靶启动子DNA缔合,同时以间接方式抑制qrr2-3转录。翻译和转录开始,sigma因子识别的核心启动子元件,用于核糖体识别的Shine-Dalgarno序列,和AphA结合位点(含有相应的AphA盒样序列)确定了三个直接的AphA靶ahpA,副溶血性弧菌的qrr4和opaR。
结论:AphA介导的对ahpA的抑制,qrr2-4和opaR在副溶血性弧菌中通过多种生化和分子实验进行了表征。计算启动子分析表明QS调节因子编码基因ahpA转录调控的保守机制,弧菌中的qrr4和opaR。
BACKGROUND: AphA is the master quorum-sensing (QS) regulator operating at low cell density in vibrios. Molecular regulation of target genes by AphA has been characterized in Vibrio harveyi and V. cholerae, but it is still poorly understood in V. parahaemolyticus.
RESULTS: The AphA proteins are extremely conserved in V. parahaemolyticus, Vibrio sp. Ex25, Vibrio sp. EJY3, V. harveyi, V. vulnificus, V. splendidus, V. anguillarum, V. cholerae, and V. furnissii. The above nine AphA orthologs appear to recognize conserved cis-acting DNA signals which can be represented by two
consensus constructs, a 20 bp box sequence and a position frequency matrix. V. parahaemolyticus AphA represses the transcription of ahpA, qrr4, and opaR through direct AphA-target promoter DNA association, while it inhibits the qrr2-3 transcription in an indirect manner. Translation and transcription starts, core promoter elements for sigma factor recognition, Shine-Dalgarno sequences for ribosome recognition, and AphA-binding sites (containing corresponding AphA box-like sequences) were determined for the three direct AphA targets ahpA, qrr4, and opaR in V. parahaemolyticus.
CONCLUSIONS: AphA-mediated repression of ahpA, qrr2-4, and opaR was characterized in V. parahaemolyticus by using multiple biochemical and molecular experiments. The computational promoter analysis indicated the conserved mechanism of transcriptional regulation of QS regulator-encoding genes ahpA, qrr4, and opaR in vibrios.