Schuster Martin, Lostroh C Phoebe, Ogi Tomoo, Greenberg E P
Department of Microbiology and W. M. Keck Microbial Communities and Cell Signaling Program, University of Iowa, Iowa City, Iowa 52242, USA.
J Bacteriol. 2003 Apr;185(7):2066-79. doi: 10.1128/JB.185.7.2066-2079.2003.
There are two interrelated acyl-homoserine lactone quorum-sensing-signaling systems in Pseudomonas aeruginosa. These systems, the LasR-LasI system and the RhlR-RhlI system, are global regulators of gene expression. We performed a transcriptome analysis to identify quorum-sensing-controlled genes and to better understand quorum-sensing control of P. aeruginosa gene expression. We compared gene expression in a LasI-RhlI signal mutant grown with added signals to gene expression without added signals, and we compared a LasR-RhlR signal receptor mutant to its parent. In all, we identified 315 quorum-induced and 38 quorum-repressed genes, representing about 6% of the P. aeruginosa genome. The quorum-repressed genes were activated in the stationary phase in quorum-sensing mutants but were not activated in the parent strain. The analysis of quorum-induced genes suggests that the signal specificities are on a continuum and that the timing of gene expression is on a continuum (some genes are induced early in growth, most genes are induced at the transition from the logarithmic phase to the stationary phase, and some genes are induced during the stationary phase). In general, timing was not related to signal concentration. We suggest that the level of the signal receptor, LasR, is a critical trigger for quorum-activated gene expression. Acyl-homoserine lactone quorum sensing appears to be a system that allows ordered expression of hundreds of genes during P. aeruginosa growth in culture.
铜绿假单胞菌中存在两个相互关联的酰基高丝氨酸内酯群体感应信号系统。这些系统，即LasR-LasI系统和RhlR-RhlI系统，是基因表达的全局调节因子。我们进行了转录组分析，以鉴定群体感应控制的基因，并更好地理解铜绿假单胞菌基因表达的群体感应控制。我们将添加信号培养的LasI-RhlI信号突变体中的基因表达与未添加信号时的基因表达进行了比较，并将LasR-RhlR信号受体突变体与其亲本进行了比较。我们总共鉴定出315个群体感应诱导基因和38个群体感应抑制基因，约占铜绿假单胞菌基因组的6%。群体感应抑制基因在群体感应突变体的稳定期被激活，但在亲本菌株中未被激活。对群体感应诱导基因的分析表明，信号特异性呈连续变化，基因表达的时间也呈连续变化（一些基因在生长早期被诱导，大多数基因在对数期向稳定期转变时被诱导，一些基因在稳定期被诱导）。一般来说，时间与信号浓度无关。我们认为信号受体LasR的水平是群体感应激活基因表达的关键触发因素。酰基高丝氨酸内酯群体感应似乎是一个在铜绿假单胞菌培养生长过程中允许数百个基因有序表达的系统。
