Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan.
Graduate School of Veterinary Science, Osaka Metropolitan University, Osaka, Japan.
Infect Immun. 2023 Jun 15;91(6):e0012122. doi: 10.1128/iai.00121-22. Epub 2023 May 9.
Providencia rustigianii is potentially enteropathogenic in humans. Recently, we identified a strain carrying a part of the gene homologous to that of that produces an exotoxin called cytolethal distending toxin (CDT), encoded by three subunit genes (, , and ). In this study, we analyzed the strain for possible presence of the entire gene cluster and its organization, location, and mobility, as well as expression of the toxin as a putative virulence factor of . Nucleotide sequence analysis revealed the presence of the three subunit genes in tandem, and over 94% homology to the corresponding genes carried by P. alcalifaciens both at nucleotide and amino acid sequence levels. The strain produced biologically active CDT, which caused distension of eukaryotic cell lines with characteristic tropism of CHO and Caco-2 cells but not of Vero cells. S1-nuclease digested pulsed-field gel electrophoresis followed by Southern hybridization analysis demonstrated that the genes in both and P. alcalifaciens strains are located on large plasmids (140 to 170 kb). Subsequently, conjugation assays using a genetically marked derivative of the strain showed that the plasmid carrying genes in the was transferable to gene-negative recipient strains of , Providencia rettgeri, and Escherichia coli. Our results demonstrated the presence of genes in for the first time, and further showed that the genes are located on a transferable plasmid, which can potentially spread to other bacterial species.
类鼻疽伯克霍尔德菌在人类中具有潜在的肠致病性。最近，我们鉴定出一株携带与产细胞肿胀毒素（CDT）的基因部分同源的基因，该毒素由三个亚基基因（cdtA、cdtB 和 cdtC）编码。在这项研究中，我们分析了该菌株是否存在整个基因簇及其组织、位置和可移动性，以及作为潜在毒力因子的毒素表达情况。核苷酸序列分析显示，三个 cdt 亚基基因串联存在，与 P. alcalifaciens 相应基因在核苷酸和氨基酸序列水平上具有 94%以上的同源性。该菌株产生了具有生物活性的 CDT，可引起真核细胞系膨胀，具有 CHO 和 Caco-2 细胞的特征性亲嗜性，但不具有 Vero 细胞的亲嗜性。S1 核酸酶消化脉冲场凝胶电泳后Southern 杂交分析表明，和 P. alcalifaciens 菌株中的基因均位于大质粒（140 至 170kb）上。随后，使用携带 基因的遗传标记衍生株进行的接合试验表明，携带基因的质粒可转移到 基因阴性的受体菌株，包括类鼻疽伯克霍尔德菌、雷氏普罗威登斯菌和大肠杆菌。我们的结果首次证明了类鼻疽伯克霍尔德菌存在基因，进一步表明这些基因位于可转移质粒上，这可能会传播到其他细菌物种。
