Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, China.
Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu, China.
Vet Res. 2023 Sep 27;54(1):83. doi: 10.1186/s13567-023-01210-9.
The LuxS quorum sensing system is a widespread system employed by many bacteria for cell-to-cell communication. The luxS gene has been demonstrated to play a crucial role in intramacrophage survival of piscine Streptococcus agalactiae, but the underlying mechanism remains largely unknown. In this study, transcriptome analysis, followed by the luxS gene deletion and subsequent functional studies, confirmed that impaired bacterial survival inside macrophages due to the inactivation of luxS was associated with reduced transcription of the fruRKI operon, encoding the fructose-specific phosphotransferase system. Further, luxS was determined not to enhance the transcription of fruRKI operon by binding its promoter, but to upregulate the expression of this operon via affecting the binding ability of catabolite control protein A (CcpA) to the catabolite responsive element (cre) in the promoter of fruRKI. Collectively, our study identifies a novel and previously unappreciated role for luxS in bacterial intracellular survival, which may give a more thorough understanding of the immune evasion mechanism in S. agalactiae.
LuxS 群体感应系统是许多细菌用于细胞间通讯的广泛系统。LuxS 基因已被证明在鱼类无乳链球菌的巨噬细胞内生存中发挥关键作用，但潜在机制在很大程度上仍不清楚。在这项研究中，通过转录组分析，随后进行 luxS 基因缺失和后续功能研究，证实由于 luxS 的失活导致细菌在巨噬细胞内的生存能力受损与果糖特异性磷酸转移酶系统编码基因 fruRKI 操纵子的转录减少有关。此外，luxS 并未通过结合其启动子来增强 fruRKI 操纵子的转录，而是通过影响分解代谢物控制蛋白 A (CcpA)与 fruRKI 启动子中分解代谢物响应元件 (cre) 的结合能力来上调该操纵子的表达。总的来说，我们的研究确定了 luxS 在细菌细胞内生存中的一个新的和以前未被认识的作用，这可能使我们更全面地了解无乳链球菌的免疫逃避机制。
