Nieckarz Marta, Kaczor Patrycja, Jaworska Karolina, Raczkowska Adrianna, Brzostek Katarzyna
Department of Molecular Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
Front Microbiol. 2020 Apr 8;11:607. doi: 10.3389/fmicb.2020.00607. eCollection 2020.
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 . 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 . 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 genes in 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 (, , and ) in strain Ye9N, but this was not the case in strain Ye8N. Binding of OmpR to the and 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 -like gene encoding a putative regulator of the 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 .
表现出双重生活方式，既作为腐生菌又作为病原体定殖于宿主生物体内的不同生态位。OmpR已被公认为一种调节因子，可控制参与许多不同细胞过程的基因表达以及病原菌的毒力。在此，我们研究了OmpR和不同温度（26°C与37°C）对Ye9N（生物血清型2/O:9，低致病性）细胞质蛋白质组的影响。无标记差异定量蛋白质组分析表明，OmpR影响许多蛋白质的细胞丰度，包括脲酶的亚基，脲酶是一种在耐酸性和致病性中起重要作用的酶。通过比较Ye9N和Ye8N（高致病性生物血清型1B/O:8）菌株中脲酶活性和脲酶基因转录，更详细地研究了不同生长条件下OmpR对脲酶表达的影响。脲酶表达在Ye9N菌株中高于Ye8N菌株，并且在26°C生长的细胞中高于37°C生长的细胞。然而，低pH、高渗透压和尿素的存在对两种菌株中的脲酶表达均无明显影响。进一步分析表明，OmpR参与Ye9N菌株中编码多亚基脲酶（、和）的三个转录单元的正调控，但Ye8N菌株中并非如此。使用电泳迁移率变动分析证实了OmpR与和启动子区域的结合，表明该因子在调节这些操纵子的转录中起直接作用。此外，我们确定OmpR调节一个类似基因的表达，该基因编码基因簇的假定调节因子，但方式相反，即在Ye9N中为正调控，在Ye8N中为负调控。这些发现为OmpR在的适应策略中的功能提供了一些新见解。
