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首页> 外文期刊>Applied Microbiology >Transcription of the Subtilase Cytotoxin Gene subAB1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns
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Transcription of the Subtilase Cytotoxin Gene subAB1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns

机译：产生志贺毒素的大肠杆菌中枯草杆菌蛋白酶细胞毒素基因subAB1的转录取决于hfq和hns

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Certain foodborne Shiga toxin-producing Escherichia coli (STEC) strains carry genes encoding the subtilase cytotoxin (SubAB). Although the mode of action of SubAB is under intensive investigation, information about the regulation of subAB gene expression is currently not available. In this study, we investigated the regulation of the chromosomal subAB1 gene in laboratory E. coli strain DH5α and STEC O113:H21 strain TS18/08 using a luciferase reporter gene assay. Special emphasis was given to the role of the global regulatory protein genes hfq and hns in subAB1 promoter activity. Subsequently, quantitative real-time PCR was performed to analyze the expression of Shiga toxin 2a (Stx2a), SubAB1, and cytolethal distending toxin V (Cdt-V) genes in STEC strain TS18/08 and its isogenic hfq and hns deletion mutants. The deletion of hfq led to a significant increase of up to 2-fold in subAB1 expression, especially in the late growth phase, in both strains. However, deletion of hns showed different effects on the promoter activity during the early and late exponential growth phases in both strains. Furthermore, upregulation of stx2a and cdt-V was demonstrated in hfq and hns deletion mutants in TS18/08. These data showed that the expression of subAB1, stx2a, and cdt-V is integrated in the regulatory network of global regulators Hfq and H-NS in Escherichia coli.IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) strains are responsible for outbreaks of foodborne diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. The pathogenicity of those strains can be attributed to, among other factors, the production of toxins. Recently, the subtilase cytotoxin was detected in locus of enterocyte effacement (LEE)-negative STEC, and it was confirmed that it contributes to the cytotoxicity of those STEC strains. Although the mode of action of SubAB1 is under intensive investigation, the regulation of gene expression is currently not known. The global regulatory proteins H-NS and Hfq have impact on many cellular processes and have been described to regulate virulence factors as well. Here, we investigate the role of hns and hfq in expression of subAB1 as well as stx2a and cdt-V in an E. coli laboratory strain as well as in wild-type STEC strain TS18/08.
机译：某些食源性产生志贺毒素的大肠杆菌（STEC）菌株携带编码枯草杆菌蛋白酶细胞毒素（SubAB）的基因。尽管SubAB的作用方式正在深入研究中，但有关SubAB基因表达调控的信息目前尚无。在这项研究中，我们使用萤光素酶报告基因检测了实验室大肠杆菌菌株DH5α和STEC O113：H21菌株TS18 / 08中染色体subAB1基因的调控。特别强调了全局调节蛋白基因hfq和hns在subAB1启动子活性中的作用。随后，进行定量实时PCR分析志贺毒素2a（Stx2a），SubAB1和细胞致死性扩展毒素V（Cdt-V）基因在STEC菌株TS18 / 08及其同基因hfq和hns缺失突变体中的表达。在两个菌株中，hfq的缺失导致subAB1表达显着增加多达2倍，尤其是在生长后期。但是，hns的删除显示在两个菌株的早期和晚期指数生长期对启动子活性的不同影响。此外，在TS18 / 08中的hfq和hns缺失突变体中证明了stx2a和cdt-V的上调。这些数据表明subAB1，stx2a和cdt-V的表达已整合到全球大肠杆菌Hfq和H-NS的调控网络中。重要事项产生志贺毒素的大肠杆菌（STEC）菌株是食源性暴发的原因疾病，例如出血性结肠炎和溶血性尿毒症综合征。这些菌株的致病性可归因于毒素的产生等。最近，在肠上皮细胞侵染（LEE）阴性的STEC的基因座中检测到枯草杆菌蛋白酶的细胞毒素，并证实其有助于这些STEC菌株的细胞毒性。尽管SubAB1的作用方式正在深入研究中，但基因表达的调控目前尚不清楚。全球调节蛋白H-NS和Hfq对许多细胞过程都有影响，并已被描述为还调节毒力因子。在这里，我们调查了hns和hfq在大肠杆菌实验室菌株以及野生型STEC菌株TS18 / 08中subAB1以及stx2a和cdt-V表达中的作用。

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