Food Safety and Environmental Microbiology Program, Department of Poultry Science, Texas A&M University, College Station, Texas 77843, USA.
Foodborne Pathog Dis. 2010 Apr;7(4):399-410. doi: 10.1089/fpd.2009.0372.
The enteric pathogen Salmonella enterica serovar Typhimurium uses autoinducer-2 (AI-2) as a signaling molecule. AI-2 requires the luxS gene for its synthesis. The regulation of global gene expression in Salmonella Typhimurium by luxS/AI-2 is currently not known; therefore, the focus of this study was to elucidate the global gene expression patterns in Salmonella Typhimurium as regulated by luxS/AI-2. The genes controlled by luxS/AI-2 were identified using microarrays with RNA samples from wild-type (WT) Salmonella Typhimurium and its isogenic DeltaluxS mutant, in two growth conditions (presence and absence of glucose) at mid-log and early stationary phases. The results indicate that luxS/AI-2 has very different effects in Salmonella Typhimurium depending on the stage of cell growth and the levels of glucose. Genes with p < or = 0.05 were considered to be significantly expressed differentially between WT and DeltaluxS mutant. In the mid-log phase of growth, AI-2 activity was higher (1500-fold) in the presence of glucose than in its absence (450-fold). There was differential gene expression of 13 genes between the WT and its isogenic DeltaluxS mutant in the presence of glucose and 547 genes in its absence. In early stationary phase, AI-2 activity was higher (650-fold) in the presence of glucose than in its absence (1.5-fold). In the presence of glucose, 16 genes were differentially expressed, and in its absence, 60 genes were differentially expressed. Our microarray study indicates that both luxS and AI-2 could play a vital role in several cellular processes including metabolism, biofilm formation, transcription, translation, transport, and binding proteins, signal transduction, and regulatory functions in addition to previously identified functions. Phenotypic analysis of DeltaluxS mutant confirmed the microarray results and revealed that luxS did not influence growth but played a role in the biofilm formation and motility.
肠病原体沙门氏菌 Typhimurium 使用自诱导物-2（AI-2）作为信号分子。AI-2 的合成需要 luxS 基因。目前尚不清楚沙门氏菌 Typhimurium 中全局基因表达受 luxS/AI-2 的调控；因此，本研究的重点是阐明 luxS/AI-2 调控的沙门氏菌 Typhimurium 的全局基因表达模式。使用微阵列和来自野生型（WT）沙门氏菌 Typhimurium 及其同源缺失突变体的 RNA 样本，在对数中期和早期稳定期的两种生长条件（存在和不存在葡萄糖）下，研究了 luxS/AI-2 控制的基因。结果表明，luxS/AI-2 在沙门氏菌 Typhimurium 中的作用因细胞生长阶段和葡萄糖水平而异。p < 0.05 的基因被认为在 WT 和 DeltaluxS 突变体之间差异显著表达。在生长的对数中期，葡萄糖存在时 AI-2 活性（1500 倍）高于不存在时（450 倍）。在葡萄糖存在时，WT 和其同源缺失突变体之间有 13 个基因差异表达，而在不存在葡萄糖时则有 547 个基因差异表达。在早期稳定期，葡萄糖存在时 AI-2 活性（650 倍）高于不存在时（1.5 倍）。在葡萄糖存在时，有 16 个基因差异表达，而在不存在葡萄糖时，则有 60 个基因差异表达。我们的微阵列研究表明，luxS 和 AI-2 都可以在包括代谢、生物膜形成、转录、翻译、运输和结合蛋白、信号转导和调节功能在内的几个细胞过程中发挥重要作用，除了先前确定的功能外。DeltaluxS 突变体的表型分析证实了微阵列结果，并表明 luxS 不影响生长，但在生物膜形成和运动中发挥作用。
