The disordered arrangement of flagella biosynthetic genes, combined with a simplified regulatory mechanism, has made elucidating the process of Campylobacter jejuni flagellation difficult. FlhF is a recently identified element that controls the assembly of the flagella, although its function mechanism and regulatory preference are not well defined at present. In this study, we found that inactivation of FlhF caused the transcription of most flagella genes down-regulated. The importance of FlhF was systematically evaluated by analyzing changes in the transcription profiles between wild-type and flhF mutant strains, which showed that FlhF affects late flagella genes obviously. FlhF is constitutively expressed during C. jejuni growth, demonstrating that it is a class I flagella element that participates in early flagella assembly. In addition, the early flagella component FlhB was not localized to the cell pole in the flhF mutant. Thus, flagella assembly was impeded at the initial stage. We propose a model in which FlhF helps target the early flagella components to the cell pole, functioning prior to the formation of the flagella export apparatus, and thus places FlhF at the top of the flagella regulatory cascade hierarchy. Inactivation of FlhF impeded flagella assembly at the initial stage and decreased transcription of flagella genes through a feed-back control mechanism, leading to FlhF having a significant influence on the expression of late flagella components and resulting in the aflagellate C. jejuni phenotype. Our present study has uncovered how FlhF influences C. jejuni flagella biosynthesis, which will be helpful in understanding the C. jejuni flagella biosynthetic pathway and bacterial flagellation in general.

鞭毛生物合成基因的无序排列，再加上简化的调节机制，使得阐明空肠弯曲菌鞭毛形成的过程变得困难。FlhF是最近发现的控制鞭毛组装的元件，尽管目前其功能机制和调控偏好尚不明确。在这项研究中，我们发现FlhF的失活导致大多数鞭毛基因的转录被下调。通过分析野生型和flhF突变株之间转录谱的变化，系统地评估了FlhF的重要性，这表明FlhF明显影响了晚期鞭毛基因。FlhF在空肠弯曲杆菌中组成性表达增长，证明它是参与鞭毛早期装配的I类鞭毛元件。另外，早期鞭毛成分FlhB未定位于flhF突变体的细胞极。因此，鞭毛的组装在初期受到阻碍。我们提出了一个模型，其中FlhF帮助将早期鞭毛成分靶向细胞极，并在鞭毛输出装置形成之前起作用，从而将FlhF置于鞭毛调节级联体系的顶部。FlhF的失活在初始阶段会阻碍鞭毛的组装，并通过反馈控制机制降低鞭毛基因的转录，从而导致FlhF对晚期鞭毛成分的表达产生重大影响，并导致无鞭毛空肠弯曲杆菌。表型。我们目前的研究发现了FlhF如何影响空肠弯曲杆菌鞭毛的生物合成，这将有助于了解空肠弯曲杆菌鞭毛的生物合成途径和细菌鞭毛的总体情况。