Genetic and molecular analyzes of bacterial flagellum which acts as a transcription-controlling apparatus

作为转录控制装置的细菌鞭毛的遗传和分子分析

基本信息

批准号：
09640737
负责人：
KUTSUKAKE Kazuhiro
金额：
$ 1.98万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640737/
关键词：
Bacterial flagella Transcriptional control Signal transduction Anti-sigma factor Flagellar hook Protein export Export switch Hook length control 輸送ゲート

项目摘要

During flagellar morphogenesis in Salmonella typhirnurium, the genes involved in filament assembly are expressed fully only after completion of hook assembly. This coupling of gene expression to morphogenesis is achieved by exporting the flagellum-specific anti-sigma factor, FlgM, out of the cell through the mature hook-basal body structure. Therefore, the flagellum-specific export apparatus must be able to sense the assembly state of the flagellar structure and to turn on FlgM export at the specific stage of hook assembly. In this study, this export switching machinery was dissected at a molecular level. The main conclusions are as follows. (1) The export gate for FlgM is double locked by FlhB and RflH proteins before completion of hook assembly. (2) These locks are opened in the mutants which produce abnormally elongated rods lacking hooks. This indicates that the monitor system of hook length measures the length of the rod plus the hook. (3) The FlgM gate is also involved in the export control of the late flagellar proteins, FlgK, FlgL, FliD, and FliC.FlhB is also responsible for shutting-off process of the export of hook protein after completion of hook assembly. (4) Mutants in which the RflH lock is opened constitutively were isolated. Genetic analysis of these mutants suggested that at least two proteins are involved in the opening process of the RflH lock. (5) The FlhB lock is opened at the early stage of hook assembly, whereas the RflH lock is opened upon completion of hook assembly.

在鼠伤寒沙门氏菌的鞭毛形态发生过程中，参与丝组装的基因只有在钩组装完成后才能完全表达。这种基因表达与形态发生的耦合是通过将鞭毛特异性抗 Sigma 因子 FlgM 通过成熟的钩基体结构输出到细胞外来实现的。因此，鞭毛特异性输出装置必须能够感知鞭毛结构的组装状态，并在钩组装的特定阶段打开FlgM输出。在这项研究中，这种输出转换机制在分子水平上进行了剖析。主要结论如下。 (1) 在完成钩组装之前，FlgM 的输出门被 FlhB 和 RflH 蛋白双重锁定。 (2) 这些锁在突变体中被打开，产生异常细长且没有钩子的杆。这表明钩长监测系统测量的是杆加钩的长度。 (3)FlgM门还参与晚期鞭毛蛋白FlgK、FlgL、FliD和FliC的输出控制。FlhB还负责钩组装完成后钩蛋白输出的关闭过程。 (4)分离出RflH锁组成型打开的突变体。这些突变体的遗传分析表明至少有两种蛋白质参与了 RflH 锁的打开过程。 (5) FlhB锁在吊钩组装初期打开，而RflH锁在吊钩组装完成后打开。