Center of Emerging and Zoonotic Diseases, National and Regional Joint Engineering Laboratory for Medicament of Zoonoses Prevention and Control, Key Laboratory of Zoonoses, Ministry of Agriculture, Key Laboratory of Zoonoses Prevention and Control of Guangdong Province, Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
Henan Institute of Modern Chinese Veterinary Medicine, Henan 450000, China.
Microbiol Res. 2023 Sep;274:127423. doi: 10.1016/j.micres.2023.127423. Epub 2023 Jun 3.
Salmonella enterica serotype Typhimurium, an important foodborne pathogen with high adaptability to the host's internal and external survival environment, seriously threatens public health. Therefore, to understand the mechanism underlying the high adaptability, this study investigated the transcription factor BolA by constructing BolA deletion strain 269△BolA, complemented strain 269BolAR and overexpression strain 269BolA+ based on WT269. BolA significantly inhibited motility; at 6 h, the BolA overexpression strain (269BolA+) showed 91.2% and 90.7% lower motility than the wild type (WT269) and BolA deletion strain (269△BolA), respectively, by downregulating motility-related flagellar genes. BolA promoted biofilm formation; 269BolA+ showed 3.6-fold and 5.2-fold higher biofilm formation ability than WT269 and 269ΔBolA, respectively, by upregulation biofilm formation-related genes. BolA overexpression downregulated the outer membrane gene OmpF and upregulated OmpC, thereby regulating cell permeability, and reducing the antibacterial effect of vancomycin, which can destruct the outer membrane. BolA improved adaptability; 269△BolA showed higher susceptibility to eight antibiotics and 2.5- and 4-fold lower acid and oxidative stress tolerance, respectively, than WT269. In Caco-2 and HeLa cells, 269△BolA showed 2.8- and 3-fold lower cell adhesion ability, respectively, and 4- and 2-fold lower cell invasion ability, respectively, than WT269, through downregulation of the virulence genes. Thus, BolA expression promotes biofilm formation and balances the membrane permeability, thereby improving the resistance of the strains, and enhances its host cell invasion ability by upregulating bacterial virulence factors. Results of this study suggest that the BolA gene may serve as a potential target of therapeutic or preventative strategies to control Salmonella Typhimurium infections.
鼠伤寒沙门氏菌血清型 Typhimurium 是一种重要的食源性病原体，具有高度适应宿主内外生存环境的能力，严重威胁着公众健康。因此，为了了解其高适应性的机制，本研究基于 WT269，构建了 BolA 缺失菌株 269△BolA、互补菌株 269BolAR 和过表达菌株 269BolA+，对转录因子 BolA 进行了研究。BolA 显著抑制了运动性；在 6 小时时，BolA 过表达菌株（269BolA+）的运动性比野生型（WT269）和 BolA 缺失菌株（269△BolA）分别低 91.2%和 90.7%，这是通过下调运动相关的鞭毛基因实现的。BolA 促进生物膜形成；269BolA+的生物膜形成能力分别比 WT269 和 269ΔBolA 高 3.6 倍和 5.2 倍，这是通过上调生物膜形成相关基因实现的。BolA 过表达下调外膜基因 OmpF 并上调 OmpC，从而调节细胞通透性，降低万古霉素的抗菌作用，破坏外膜。BolA 提高了适应性；269△BolA 对八种抗生素的敏感性比 WT269 更高，对酸和氧化应激的耐受性分别低 2.5 倍和 4 倍。在 Caco-2 和 HeLa 细胞中，269△BolA 的细胞黏附能力分别比 WT269 低 2.8 倍和 3 倍，细胞侵袭能力分别低 4 倍和 2 倍，这是通过下调毒力基因实现的。因此，BolA 的表达促进了生物膜的形成，并平衡了膜的通透性，从而提高了菌株的抗性，并通过上调细菌毒力因子增强了其宿主细胞的侵袭能力。本研究结果表明，BolA 基因可能成为控制鼠伤寒沙门氏菌感染的治疗或预防策略的潜在靶点。
