利用單分子螢光顯微術與螢光相干光譜解析細菌鞭毛與第三型分泌系統數量與位置之控制機制

Regulated by the chemotaxis system, the bacterial flagellum, the major organelle for swimming, alter the bacterial motion behaviors with the respective directions of rotation. Assembled by more than 20 different proteins, it becomes the ideal case of self-assembly and one of the classical models of biomimics. After detailed studies, the fine structure of a bacterial flagellum has been reported. However, it is unknown how a peritrichous bacterial cell, including E. coli, designs the number and location of its flagella. It is found that the proteins involving in the initiation of flagellar assembly have been non-uniformly surrounded by the basal bodies of existed flagella. To verify this coordination, the single-molecule super-resolution microscopy has been applied to measure the distribution and motion behaviors of the two proteins, FliF and FlhA, in the basal bodies which involve in the first step of the assembly process of bacterial flagella. By further analysis of the distribution of the protein loci, the clustering behaviors, and the possible mechanism of the proteins then have been resolved. It is found that the FlhA proteins seem to play the leading role in the initiation of the cluster formation and the stabilization of the cluster then requires the participation of FliF proteins. Further, from the variant sizes of the protein clusters, not only the clustered type of protein assemblies have been confirmed in the wild-type cells, the role as buffers can be implied by the observation in cells with different protein expression levels.