Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801, USA.
J Bacteriol. 2010 Nov;192(21):5767-77. doi: 10.1128/JB.00624-10. Epub 2010 Sep 10.
Salmonella enterica, a common food-borne pathogen, differentially regulates the expression of multiple genes during the infection cycle. These genes encode systems related to motility, adhesion, invasion, and intestinal persistence. Key among them is a type three secretion system (T3SS) encoded within Salmonella pathogenicity island 1 (SPI1). In addition to the SPI1 T3SS, other systems, including flagella and type 1 fimbriae, have been implicated in Salmonella pathogenesis. In this study, we investigated the dynamic expression of the flagellar, SPI1, and type 1 fimbrial genes. We demonstrate that these genes are expressed in a temporal hierarchy, beginning with the flagellar genes, followed by the SPI1 genes, and ending with the type 1 fimbrial genes. This hierarchy could mirror the roles of these three systems during the infection cycle. As multiple studies have shown that extensive regulatory cross talk exists between these three systems, we also tested how removing different regulatory links between them affects gene expression dynamics. These results indicate that cross talk is critical for regulating gene expression during transitional phases in the gene expression hierarchy. In addition, we identified a novel regulatory link between flagellar and type 1 fimbrial gene expression dynamics, where we found that the flagellar regulator, FliZ, represses type 1 fimbrial gene expression through the posttranscriptional regulation of FimZ. The significance of these results is that they provide the first systematic study of the effect of regulatory cross talk on the expression dynamics of flagellar, SPI1, and type 1 fimbrial genes.
肠道沙门氏菌是一种常见的食源性病原体,在感染周期中会差异调控多个基因的表达。这些基因编码与运动性、黏附性、侵袭性和肠道持久性相关的系统。其中关键的是一种类型三分泌系统(T3SS),它编码在沙门氏菌致病岛 1(SPI1)内。除了 SPI1 T3SS 外,其他系统,包括鞭毛和类型 1 菌毛,也与沙门氏菌发病机制有关。在这项研究中,我们研究了鞭毛、SPI1 和类型 1 菌毛基因的动态表达。我们证明这些基因按照时间顺序表达,首先是鞭毛基因,其次是 SPI1 基因,最后是类型 1 菌毛基因。这种顺序可能反映了这三个系统在感染周期中的作用。由于多项研究表明这三个系统之间存在广泛的调控交叉对话,我们还测试了去除它们之间不同的调控联系如何影响基因表达动力学。这些结果表明,交叉对话对于调控基因表达在基因表达层次的过渡阶段是至关重要的。此外,我们发现了鞭毛和类型 1 菌毛基因表达动力学之间的一种新的调控联系,其中我们发现鞭毛调节因子 FliZ 通过对 FimZ 的转录后调节来抑制类型 1 菌毛基因的表达。这些结果的意义在于,它们提供了第一个系统性研究调控交叉对话对鞭毛、SPI1 和类型 1 菌毛基因表达动力学的影响的研究。