Genetic Analysis of the Salmonella FliE Protein That Forms the Base of the Flagellar Axial Structure.
Genetic Analysis of the Salmonella FliE Protein That Forms the Base of the Flagellar Axial Structure.
复制标题
DOI：
10.1128/mbio.02392-21
复制
发表时间：
2021-10-26
期刊：
影响因子：
6.4
通讯作者：
Hughes KT
中科院分区：
文献类型：
--
作者：
Hendriksen JJ;Lee HJ;Bradshaw AJ;Namba K;Chevance FFV;Minamino T;Hughes KT
细菌鞭毛的FliE组分是通过鞭毛III型分泌系统（fT 3SS）分泌的第一种蛋白质，其能够自组装成生长的细菌细胞器。FliE蛋白在沙门氏菌鞭毛的组装中起双重作用，作为鞭毛III型分泌系统（fT 3SS）的最终组分，以及作为将鞭毛马达的杆（驱动轴）锚定到膜嵌入的MS环结构的衔接蛋白。这项工作已经确定了FliE和其他蛋白质之间的相互作用在鞭毛机器的内膜基底。对编码104个氨基酸的蛋白质的fliE序列进行饱和诱变。在fliE中产生单个氨基酸取代，导致运动表型。从这些突变体中，基因间抑制突变产生，分离和表征。FliE功能缺陷的单氨基酸突变定位于蛋白质的N-和C-末端螺旋。fliE中氨基酸突变的运动抑制因子存在于杆蛋白基因flgB和flgC、MS环基因fliF和核心T3 SS基因之一fliR中。这些结果支持以下假设：FliE作为连接蛋白，由参与与具有旋转对称性的MS环相互作用的N-末端α-螺旋和与FliF、FliR、FlgB和FlgC相互作用的C-末端卷曲螺旋组成，并且这些相互作用打开fT 3SS的蛋白输出通道的出口门。
The FliE component of the bacterial flagellum is the first protein secreted through the flagellar type III secretion system (fT3SS) that is capable of self-assembly into the growing bacterial organelle. The FliE protein plays dual roles in the assembly of the Salmonella flagellum as the final component of the flagellar type III secretion system (fT3SS) and as an adaptor protein that anchors the rod (drive shaft) of the flagellar motor to the membrane-imbedded MS-ring structure. This work has identified the interactions between FliE and other proteins at the inner membrane base of the flagellar machine. The fliE sequence coding for the 104-amino-acid protein was subject to saturating mutagenesis. Single-amino-acid substitutions were generated in fliE, resulting in motility phenotypes. From these mutants, intergenic suppressor mutations were generated, isolated, and characterized. Single-amino-acid mutations defective in FliE function were localized to the N- and C-terminal helices of the protein. Motile suppressors of amino acid mutations in fliE were found in rod protein genes flgB and flgC, the MS ring gene, fliF, and one of the core T3SS genes, fliR. These results support the hypothesis that FliE acts as a linker protein consisting of an N-terminal α-helix that is involved in the interaction with the MS ring with a rotational symmetry and a C-terminal coiled coil that interacts with FliF, FliR, FlgB, and FlgC, and these interactions open the exit gate of the protein export channel of the fT3SS.