Department of Microbiology, Infectiology and Immunology, University of Montréal, 2900 Bd Édouard-Montpetit, Montreal, QC, H3T 1J4, Canada.
CRIPA, Centre de Recherche en Infectiologie Porcine et Avicole, Faculté de Médecine Vétérinaire, 3200 Sicotte, St-Hyacinthe, QC, J2S 2M2, Canada.
Sci Rep. 2023 Sep 9;13(1):14905. doi: 10.1038/s41598-023-42027-y.
The human-specific Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a systemic disease with no known reservoir. Curli fimbriae are major components of biofilm produced by Salmonella and are encoded by the csg gene cluster (csgBAC and csgDEFG). The role of curli in S. Typhi is unknown, although detection of anti-curli antibodies suggests they are produced during host infection. In this study, we investigated curli gene expression in S. Typhi. We demonstrated that the CsgD regulatory protein binds weakly to the csgB promoter. Yet, replacing S. Typhi csgD with the csgD allele from S. Typhimurium did not modify the curli negative phenotype on Congo Red medium suggesting that differential regulation of curli gene expression in S. Typhi is not dependent on modification of the CsgD regulator. The entire csg gene cluster from S. Typhimurium was also cloned into S. Typhi, but again, despite introduction of a fully functional csg gene cluster from S. Typhimurium, curli were still not detected in S. Typhi. Thus, in addition to intrinsic genomic differences in the csg gene cluster that have resulted in production of a modified CsgD protein, S. Typhi has likely undergone other changes independent of the csg gene cluster that have led to distinctive regulation of csg genes compared to other Salmonella serovars.
人类特异性肠炎沙门氏菌血清型 Typhi（S. Typhi）引起伤寒，这是一种全身性疾病，没有已知的宿主。卷曲菌毛是沙门氏菌生物膜的主要成分，由 csg 基因簇（csgBAC 和 csgDEFG）编码。卷曲菌毛在 S. Typhi 中的作用尚不清楚，尽管检测到抗卷曲菌毛抗体表明它们在宿主感染期间产生。在这项研究中，我们研究了 S. Typhi 中卷曲菌基因的表达。我们证明了 CsgD 调节蛋白与 csgB 启动子弱结合。然而，用 S. Typhimurium 的 csgD 取代 S. Typhi 的 csgD 等位基因并没有改变刚果红培养基上卷曲菌阴性表型，这表明 S. Typhi 中卷曲菌基因表达的差异调节不依赖于 CsgD 调节剂的修饰。来自 S. Typhimurium 的整个 csg 基因簇也被克隆到 S. Typhi 中，但尽管从 S. Typhimurium 引入了一个功能齐全的 csg 基因簇，在 S. Typhi 中仍未检测到卷曲菌。因此，除了 csg 基因簇中导致产生修饰的 CsgD 蛋白的内在基因组差异外，S. Typhi 可能还发生了其他独立于 csg 基因簇的变化，导致 csg 基因的调节与其他沙门氏菌血清型明显不同。
