Ma Zhongmei, Ma Jifu, Li Jie, Wang Zhanpeng, Wei Lixiang, Ali Ahmad, Zuo Yufei, Cai Xuepeng, Meng Qingling, Qiao Jun
College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang 832003, China.
State Key Lab of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu 730046, China.
Int J Food Microbiol. 2025 Mar 2;431:111088. doi: 10.1016/j.ijfoodmicro.2025.111088. Epub 2025 Jan 29.
Salmonella Typhimurium (S. typhimurium) is a significant zoonotic pathogen responsible for gastroenteritis and severe systemic infections in various hosts. The AraC family transcription factors are key gene expression regulators in prokaryotes, essential for bacterial adaptation to the environment and virulence. Despite their importance, the role of yeaM, a member of this family in S. typhimurium, remains unexplored. To elucidate yeaM regulatory function in virulence and biofilm formation, we engineered mutant and complementary strains of the yeaM gene using homologous recombination. We assessed their capabilities in biofilm formation under different conditions, macrophage adherence and invasion, and virulence in mice. Additionally, we identified potential target genes regulated by yeaM through transcriptome sequencing and confirmed these findings using an electrophoretic mobility shift assay (EMSA) and a dual-luciferase reporter assay. Our results demonstrate that, compared to the parental strain SL1344 and the complemented strain CΔyeaM, the ΔyeaM strain exhibited significantly enhanced biofilm formation, increased invasion of mouse intestinal epithelial cells, enhanced intracellular proliferation within macrophages, and elevated induction of macrophage apoptosis. Furthermore, the ΔyeaM deletion strain displayed significantly increased virulence in mice and enhanced proliferation in milk. Transcriptome analysis revealed that S. typhimurium pathogenicity island 4 (SPI4) genes (siiA, siiB, siiC, siiD, siiF, and siiE) were significantly upregulated following the deletion of the yeaM gene. EMSA and dual-luciferase reporter assays further showed that the yeaM protein can bind to the promoter of the siiA gene and suppress its expression, thereby modulating the biofilm formation and virulence of S. typhimurium.
鼠伤寒沙门氏菌是一种重要的人畜共患病原体，可导致多种宿主发生肠胃炎和严重的全身感染。AraC家族转录因子是原核生物中关键的基因表达调节因子，对细菌适应环境和致病性至关重要。尽管它们很重要，但该家族成员yeaM在鼠伤寒沙门氏菌中的作用仍未得到探索。为了阐明yeaM在致病性和生物膜形成中的调节功能，我们利用同源重组构建了yeaM基因的突变体和互补菌株。我们评估了它们在不同条件下形成生物膜的能力、对巨噬细胞的黏附和侵袭能力以及在小鼠中的致病性。此外，我们通过转录组测序鉴定了受yeaM调控的潜在靶基因，并使用电泳迁移率变动分析（EMSA）和双荧光素酶报告基因分析证实了这些发现。我们的结果表明，与亲本菌株SL1344和互补菌株CΔyeaM相比，ΔyeaM菌株表现出显著增强的生物膜形成能力、对小鼠肠上皮细胞侵袭的增加、巨噬细胞内增殖的增强以及巨噬细胞凋亡诱导的升高。此外，ΔyeaM缺失菌株在小鼠中的致病性显著增加，在牛奶中的增殖能力增强。转录组分析显示，鼠伤寒沙门氏菌致病岛4（SPI4）基因（siiA、siiB、siiC、siiD、siiF和siiE）在yeaM基因缺失后显著上调。EMSA和双荧光素酶报告基因分析进一步表明，yeaM蛋白可以结合到siiA基因的启动子上并抑制其表达，从而调节鼠伤寒沙门氏菌的生物膜形成和致病性。
