School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, India.
Department of Pediatrics, Kalinga Institute of Medical Sciences, Bhubaneswar, India.
J Bacteriol. 2020 Dec 7;203(1). doi: 10.1128/JB.00237-20.
An essential feature of the pathogenesis of the serovar Enteritidis wild type (WT) is its ability to survive under diverse microenvironmental stress conditions, such as encountering antimicrobial peptides (AMPs) or glucose and micronutrient starvation. These stress factors trigger virulence genes carried on pathogenicity islands (SPIs) and determine the efficiency of enteric infection. Although the oligosaccharide/oligonucleotide binding-fold (OB-fold) family of proteins has been identified as an important stress response and virulence determinant, functional information on members of this family is currently limited. In this study, we decipher the role of YdeI, which belongs to OB-fold family of proteins, in stress response and virulence of Enteritidis. When was deleted, the Δ mutant showed reduced survival during exposure to AMPs or glucose and Mg starvation stress compared to the WT. Green fluorescent protein (GFP) reporter and quantitative real-time PCR (qRT-PCR) assays showed was transcriptionally regulated by PhoP, which is a major regulator of stress and virulence. Furthermore, the Δ mutant displayed ∼89% reduced invasion into HCT116 cells, ∼15-fold-reduced intramacrophage survival, and downregulation of several SPI-1 and SPI-2 genes encoding the type 3 secretion system apparatus and effector proteins. The mutant showed attenuated virulence compared to the WT, confirmed by its reduced bacterial counts in feces, mesenteric lymph node (mLN), spleen, and liver of C57BL/6 mice. qRT-PCR analyses of the Δ mutant displayed differential expression of 45 PhoP-regulated genes, which were majorly involved in metabolism, transport, membrane remodeling, and drug resistance under different stress conditions. YdeI is, therefore, an important protein that modulates Enteritidis virulence and adaptation to stress during infection. Enteritidis during its life cycle encounters diverse stress factors inside the host. These intracellular conditions allow activation of specialized secretion systems to cause infection. We report a conserved membrane protein, YdeI, and elucidate its role in protection against various intracellular stress conditions. A key aspect of the study of a pathogen's stress response mechanism is its clinical relevance during host-pathogen interaction. Bacterial adaptation to stress plays a vital role in evolution of a pathogen's resistance to therapeutic agents. Therefore, investigation of the role of YdeI is vital for understanding the molecular basis of regulation of pathogenesis. In conclusion, our findings may contribute to finding potential targets to develop new intervention strategies for treatment and prevention of enteric diseases.
肠炎沙门氏菌野毒株（WT）发病机制的一个重要特征是其在多种微环境应激条件下生存的能力，例如遇到抗菌肽（AMPs）或葡萄糖和微量营养素饥饿。这些应激因素会触发位于致病性岛（SPIs）上的毒力基因，并决定肠内感染的效率。虽然寡糖/寡核苷酸结合折叠（OB-fold）家族蛋白已被确定为重要的应激反应和毒力决定因素，但该家族成员的功能信息目前有限。在这项研究中，我们揭示了 YdeI 在肠炎沙门氏菌的应激反应和毒力中的作用。当缺失时，与 WT 相比，Δ突变体在暴露于 AMPs 或葡萄糖和 Mg 饥饿应激时的存活能力降低。绿色荧光蛋白（GFP）报告基因和实时定量 PCR（qRT-PCR）检测表明，PhoP 转录调控，PhoP 是应激和毒力的主要调节因子。此外，Δ突变体在侵袭 HCT116 细胞方面的能力降低了约 89%，在巨噬细胞内的存活能力降低了约 15 倍，并且编码 III 型分泌系统装置和效应蛋白的 SPI-1 和 SPI-2 基因的表达下调。与 WT 相比，突变体的毒力减弱，通过其在 C57BL/6 小鼠粪便、肠系膜淋巴结（mLN）、脾脏和肝脏中的细菌计数减少得到证实。Δ突变体的 qRT-PCR 分析显示，在不同应激条件下，PhoP 调控的 45 个基因差异表达，这些基因主要参与代谢、运输、膜重塑和耐药性。因此，YdeI 是一种重要的调节蛋白，可调节肠炎沙门氏菌的毒力并适应感染期间的应激。肠炎沙门氏菌在其生命周期中会在宿主内遇到多种应激因素。这些细胞内条件允许激活专门的分泌系统以引起感染。我们报告了一种保守的膜蛋白 YdeI，并阐明了其在抵抗各种细胞内应激条件中的作用。研究病原体应激反应机制的一个关键方面是其在宿主-病原体相互作用过程中的临床相关性。细菌对压力的适应在病原体对治疗药物的耐药性进化中起着至关重要的作用。因此，研究 YdeI 的作用对于理解发病机制的调节的分子基础至关重要。总之，我们的发现可能有助于找到潜在的靶点，为治疗和预防肠道疾病开发新的干预策略。
