Starke Mandy, Fuchs Thilo M
Lehrstuhl für Mikrobielle Ökologie, Department für biowissenschaftliche Grundlagen, Wissenschaftszentrum Weihenstephan, Technische Universität München, Weihenstephaner Berg 3, 85354, Freising, Germany.
Mol Microbiol. 2014 Apr;92(2):287-301. doi: 10.1111/mmi.12554. Epub 2014 Mar 13.
Yersinia enterocolitica is toxic towards invertebrates due to the presence of the toxin complex (tc) genes that are activated by the thermolabile regulator TcaR2. In the search for further regulatory factors involved in insecticidal gene expression, the modulator of yersinial virulence, YmoA, was identified to silence all tc genes of the Y. enterocolitica strain W22703 (biovar 2, serovar O:9). Using promoter fusions with the luciferase reporter, we found that the deletion of ymoA results in elevated transcription of tcaR1, tcaR2, tcaA, tcaB, tcaC, tccC1 and tccC2 at both 15 °C and 37 °C. Complementation by episomal ymoA significantly reduced tc gene expression, thus validating the inhibitory activity of YmoA on the production of insecticidal proteins. YmoA contributes to the binding properties of H-NS to the tc promoters by forming a complex with this nucleoid-associated protein, and this complex not only binds to the upstream regions of all tc genes, but also to intragenic sites of tcaA and tcaB that play an important role in controlling the expression of both genes. At low temperature, the intracellular amount of thermostable YmoA is not reduced, but the repressor is less functional. These data point to H-NS/YmoA as an antagonist of the inducer TcaR2.
由于存在由不耐热调节因子TcaR2激活的毒素复合物（tc）基因，小肠结肠炎耶尔森菌对无脊椎动物具有毒性。在寻找参与杀虫基因表达的其他调节因子时，发现耶尔森菌毒力调节剂YmoA可使小肠结肠炎耶尔森菌菌株W22703（生物变种2，血清型O:9）的所有tc基因沉默。通过与荧光素酶报告基因的启动子融合，我们发现ymoA的缺失导致tcaR1、tcaR2、tcaA、tcaB、tcaC、tccC1和tccC2在15℃和37℃时的转录水平升高。附加体ymoA的互补显著降低了tc基因的表达，从而验证了YmoA对杀虫蛋白产生的抑制活性。YmoA通过与这种类核相关蛋白形成复合物，有助于H-NS与tc启动子的结合特性，并且这种复合物不仅与所有tc基因的上游区域结合，还与tcaA和tcaB的基因内位点结合，这些位点在控制这两个基因的表达中起重要作用。在低温下，耐热YmoA的细胞内含量没有减少，但阻遏物的功能较弱。这些数据表明H-NS/YmoA是诱导物TcaR2的拮抗剂。
