Yersinia enterocolitica exhibits a dual lifestyle, existing as both a saprophyte and a pathogen colonizing different niches within a host organism. OmpR has been recognized as a regulator that controls the expression of genes involved in many different cellular processes and the virulence of pathogenic bacteria. Here, we have examined the influence of OmpR and varying temperature (26°C vs. 37°C) on the cytoplasmic proteome of Y. enterocolitica Ye9N (bio-serotype 2/O:9, low pathogenicity). Differential label-free quantitative proteomic analysis indicated that OmpR affects the cellular abundance of a number of proteins including subunits of urease, an enzyme that plays a significant role in acid tolerance and the pathogenicity of Y. enterocolitica. The impact of OmpR on the expression of urease under different growth conditions was studied in more detail by comparing urease activity and the transcription of ure genes in Y. enterocolitica strains Ye9N and Ye8N (highly pathogenic bio-serotype 1B/O:8). Urease expression was higher in strain Ye9N than in Ye8N and in cells grown at 26°C compared to 37°C. However, low pH, high osmolarity and the presence of urea did not have a clear effect on urease expression in either strain. Further analysis showed that OmpR participates in the positive regulation of three transcriptional units encoding the multi-subunit urease (ureABC, ureEF, and ureGD) in strain Ye9N, but this was not the case in strain Ye8N. Binding of OmpR to the ureABC and ureEF promoter regions was confirmed using an electrophoretic mobility shift assay, suggesting that this factor plays a direct role in regulating the transcription of these operons. In addition, we determined that OmpR modulates the expression of a ureR-like gene encoding a putative regulator of the ure gene cluster, but in the opposite manner, i.e., positively in Ye9N and negatively in Ye8N. These findings provide some novel insights into the function of OmpR in adaptation strategies of Y. enterocolitica.

中文翻译：

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生物血清型 2/O:9 和 1B/O:8 的致病性小肠结肠炎耶尔森氏菌菌株中的脲酶表达受 OmpR 调节器的差异调节。


小肠结肠炎耶尔森氏菌表现出双重生活方式，既作为腐生菌又作为定植于宿主生物体内不同生态位的病原体存在。 OmpR 已被认为是一种调节因子，可控制参与许多不同细胞过程和病原菌毒力的基因表达。在这里，我们研究了 OmpR 和不同温度（26°C 与 37°C）对小肠结肠炎耶氏菌 Ye9N（生物血清型 2/O:9，低致病性）细胞质蛋白质组的影响。差异无标记定量蛋白质组分析表明，OmpR 影响许多蛋白质的细胞丰度，包括脲酶亚基，脲酶是一种在小肠结肠炎耶尔森氏菌的耐酸性和致病性中发挥重要作用的酶。通过比较小肠结肠炎耶氏菌菌株 Ye9N 和 Ye8N（高致病性生物血清型 1B/O:8）中脲酶活性和 ure 基因的转录，更详细地研究了 OmpR 在不同生长条件下对脲酶表达的影响。菌株 Ye9N 中的脲酶表达高于 Ye8N，并且在 26°C 下生长的细胞中与 37°C 下生长的细胞相比。然而，低pH、高渗透压和尿素的存在对任一菌株中的脲酶表达均没有明显影响。进一步分析表明，在菌株Ye9N中，OmpR参与了编码多亚基脲酶的三个转录单元（ureABC、ureEF和ureGD）的正向调控，但在菌株Ye8N中却并非如此。使用电泳迁移率变动测定证实了 OmpR 与 ureABC 和 ureEF 启动子区域的结合，表明该因子在调节这些操纵子的转录中发挥直接作用。 此外，我们确定OmpR 调节编码ure 基因簇的假定调节因子的ureR 样基因的表达，但以相反的方式，即在Ye9N 中为正向调节，而在Ye8N 中为负向调节。这些发现为 OmpR 在小肠结肠炎耶尔森氏菌适应策略中的功能提供了一些新的见解。