Kapatral V, Olson J W, Pepe J C, Miller V L, Minnich S A
Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow 83843, USA.
Mol Microbiol. 1996 Mar;19(5):1061-71. doi: 10.1046/j.1365-2958.1996.452978.x.
Temperature is a key environmental cue for Yersinia enterocolitica as well as for the two other closely related pathogens, Yersinia pestis and Yersinia pseudotuberculosis. Between the range of 30 degrees C and 37 degrees C, Y. enterocolitica phase-varies between motility and plasmid-encoded virulence gene expression. To determine how temperature regulates Y. enterocolitica motility, we have been dissecting the flagellar regulatory hierarchy to determine at which level motility is blocked by elevated temperature (37 degrees C). Here we report the cloning, DNA sequences, and regulation of the two main regulators of Class III flagellar genes, fliA (sigma F) and flgM (anti-sigma F), and a third gene, flgN, which we show is required for filament assembly. Identification of the Y. enterocolitica fliA and flgM genes was accomplished by functional complementation of both S. typhimurium and Y. enterocolitica mutations and by DNA sequence analysis. The Y. enterocolitica fliA gene, encoding the flagellar-specific sigma-factor, sigma F, maps immediately downstream of the three flagellin structural genes. The flgM and flgN genes, encoding anti-sigma F and a gene product required for filament assembly, respectively, map downstream of the invasin (inv) gene but are transcribed in the opposite (convergent) direction. By using Northern blot analyses we show that transcription of both fliA and flgM is immediately arrested when cells are exposed to 37 degrees C, coincident with the timing of virulence gene induction. Unlike S. typhimurium flgM mutants, Y. enterocolitica flgM mutants are fully virulent.
温度是小肠结肠炎耶尔森菌以及另外两种密切相关的病原体——鼠疫耶尔森菌和假结核耶尔森菌的关键环境信号。在30摄氏度至37摄氏度的范围内，小肠结肠炎耶尔森菌会在运动性和质粒编码的毒力基因表达之间发生相变。为了确定温度如何调节小肠结肠炎耶尔森菌的运动性，我们一直在剖析鞭毛调控层级，以确定在哪个水平运动性会被升高的温度（37摄氏度）所阻断。在此我们报告III类鞭毛基因的两个主要调控因子fliA（σF）和flgM（抗σF）以及第三个基因flgN的克隆、DNA序列和调控情况，我们发现flgN是鞭毛丝组装所必需的。通过对鼠伤寒沙门氏菌和小肠结肠炎耶尔森菌突变体的功能互补以及DNA序列分析，完成了小肠结肠炎耶尔森菌fliA和flgM基因的鉴定。小肠结肠炎耶尔森菌的fliA基因编码鞭毛特异性σ因子σF，定位于三个鞭毛蛋白结构基因的紧邻下游。flgM和flgN基因分别编码抗σF和鞭毛丝组装所需的基因产物，定位于侵袭素（inv）基因的下游，但转录方向相反（反向）。通过Northern印迹分析我们发现，当细胞暴露于37摄氏度时，fliA和flgM的转录会立即停止，这与毒力基因诱导的时间一致。与鼠伤寒沙门氏菌的flgM突变体不同，小肠结肠炎耶尔森菌的flgM突变体具有完全的毒力。
