空肠弯曲菌( Campylobacter jejuni) 是人类细菌性胃肠炎的病原体。趋化是细菌向合适的寄生部位定向运动, 也是空肠弯曲菌在宿主空肠黏膜表面实现定植的关键起始步骤, 该趋化运动由趋化相关二元信号系统( che-TCS) 以MCPs→Ches→Flis/Mots 方式调控。FliG是Fli 蛋白家族成员, 一些病原菌的FliG被证明是鞭毛马达蛋白, 也是细菌鞭毛马达中开关复合体的必需组分, 但空肠弯曲菌FliG在细菌趋化中的作用未明。本研究中, 我们根据同源重组原理, 构建空肠弯曲菌NCTC11168 株fliG基因敲除( fliG^- ) 突变株, 然后对fliG^- 突变株的动力、趋化和定植能力进行测定。动力实验和体外趋化实验结果证实, fliG^- 突变株在半固体琼脂平板上的菌落直径、在硬琼脂平板上对0. 2 mol/L 脱氧胆酸钠( SDC) 的趋化聚集环直径均明显小于野生株( P <0. 05) 。与野生株比较, 黏附于BALB/c-ByJ小鼠空肠黏膜表面以及空肠内容物中的fliG^- 突变株数量也明显减少( P <0. 05) 。实验结果表明, fliG是空肠弯曲菌鞭毛动力以及细菌感染时向空肠黏膜趋化运动的必需基因。

Campylobacter jejuni ( C. jejuni) is a common causative pathogen of bacterial gastroenteritis in humans. Chemotaxis, adirectional movement of bacteria towards suitable parasitic positions, is the initial key step for C. jejuni to achieve colonization on jejunal mucosa of hosts. The chemotactic migration was controlled and regulated by bacterial chemotaxis-associated two-component signaling system( che-TCS) in a MCPs→Ches→Flis/Mots manner. FliG, amember of Fli protein family, has been confirmed in some other bacterial pathogens to be a flagellar motor protein as well as an essential component of switch complex in bacterial flagellar motor. However, the function of FliG protein in chemotaxis of C. jejuni remains unknown. In the present study we generated a fliG gene knockout ( fliG^- ) mutant from C. jejuni strain NCTC11168 based on homologous recombination, and the motility, chemotaxis and colonization of fliG^- mutant were subsequently determined. The motility test and chemotaxis test in vitro demonstrated that the diameters of colonies on semisolid agar plate and chemotactic rings towards 0. 2 mol/L sodiumdeoxycholate ( SDC) in hard agar plus (HAP) of fliG^- mutant were significantly smaller than those of the wild type strain ( P < 0. 05) . Compared to the wild type strain, the numbers of fliG^- mutant adhering to the surface of jejunal mucosa and existing in jejunal content of BALB/c-ByJ mice were also significantly decreased ( P <0. 05) . All the results of this study lead a conclusion that fliG is an essential gene for flagellar motility and chemotactic movement towards jejunal
mucosa of C. jejuni during infection.