Horne Shelley M, Prüss Birgit M
Department of Veterinary and Microbiological Sciences, North Dakota State University, 1523 Centennial Blvd., Fargo, ND 58105, USA.
Arch Microbiol. 2006 Mar;185(2):115-26. doi: 10.1007/s00203-005-0077-1. Epub 2006 Jan 11.
This study describes the involvement of the sigma factor of the flagellar system, FliA, in global gene regulation of Yersinia enterocolitica. In addition to exhibiting a positive effect upon the expression levels of eight class III flagellar operons, FliA also exhibited a negative effect upon the expression levels of four virulence operons that are located on the pYV virulence plasmid. These are yadA, virC, yopQ, and the insertion element ISYen1. While the positive effect on class III flagellar operons by FliA is most likely direct, the negative effect on the virulence operons appears to require the known transcriptional activator of these genes, VirF. This was determined using microarray analysis, quantitative PCR and a search for putative binding sites for FliA. In addition to the FliA regulation of flagellar and plasmid-encoded virulence genes, we studied temperature regulation of these genes. While wild-type cells exhibited increased expression levels of flagellar genes and decreased expression levels of plasmid-encoded virulence genes at 25 degrees C (as compared to 37 degrees C), temperature dependence of gene expression was much reduced in the fliA mutants. We conclude that FliA contributes to the inverse temperature regulation of flagellar and plasmid-encoded virulence genes. We present a network of transcriptional regulation around FlhD/FlhC and FliA.
本研究描述了鞭毛系统的σ因子FliA参与小肠结肠炎耶尔森菌的全局基因调控。除了对8个III类鞭毛操纵子的表达水平有正向作用外，FliA对位于pYV毒力质粒上的4个毒力操纵子的表达水平也有负向作用。这些操纵子是yadA、virC、yopQ和插入元件ISYen1。虽然FliA对III类鞭毛操纵子的正向作用很可能是直接的，但对毒力操纵子的负向作用似乎需要这些基因已知的转录激活因子VirF。这是通过微阵列分析、定量PCR以及寻找FliA的假定结合位点来确定的。除了FliA对鞭毛和质粒编码的毒力基因的调控外，我们还研究了这些基因的温度调控。虽然野生型细胞在25℃时鞭毛基因的表达水平增加，质粒编码的毒力基因的表达水平降低（与37℃相比），但在fliA突变体中基因表达的温度依赖性大大降低。我们得出结论，FliA有助于鞭毛和质粒编码的毒力基因的反向温度调控。我们提出了围绕FlhD/FlhC和FliA的转录调控网络。
