Molecular analysis of the export-switching apparatus of the anti-sigma factor which regulates the bacterial flagellar regulon

1. FlgJ蛋白显示出具有胞壁酶活性，该活性涉及肽聚糖层通过杆状结构的穿透过程。FlgA被证明是P环形成所必需的周质伴侣。N-末端三分之一的FlgD蛋白被证明参与调制的钩组装，而其C末端部分被发现，以提高翻译和出口的钩蛋白。这表明钩蛋白完成的监控系统可能依赖于FlgD介导的钩蛋白翻译与其输出的偶联.发现FlgM出口门在钩组装的初始步骤打开。这表明钩组装可以用已经通过钩组装的起始步骤并入输出装置中的钩蛋白池进行。北方印迹分析发现一个200个碱基的RNA分子来源于flgB mRNA。该RNA的长度对应于基体-钩结构的轴向长度，表明该RNA可能参与钩长度控制。fliC-lacZ翻译融合的表达分析显示，其表达在钩组装后被轻微抑制。这表明fliC基因的抑制控制机制可能建立在钩子完成上。

1. FlgJ protein was shown to have a muramidase activity involved in penetration process of the peptidoglycan layer by the rod structure. FlgA was shown to be a periplasmic chaperone essential for P-ring formation.2. N-terminal one third of the FlgD protein was shown to be involved in modulation of hook assembly, whereas its C terminal portion was found to enhance the translation and export of the hook protein. This suggests that the monitor system of hook completion may depend upon the FlgD-mediated coupling of translation of the hook protein to its export.3. The FlgM export gate was found to be turned on at the initiation step of hook assembly. This suggests that hook assembly may be carried out with the pool of hook protein which has been already incorporated into the export apparatus by the initiation step of hook assembly.4. Northern blotting analysis found a 200-base RNA molecule derived from the flgB mRNA. The length of this RNA corresponds to axial length of the basal body-hook structure, suggesting that this RNA may be involved in the hook length control. Expression analysis of the fliC-lacZ translational fusion revealed that its expression is slightly repressed after hook assembly. This suggests that translation-controlling machinery of the fliC gene may be established on hook completion.