The role of intrinsically disordered C-terminal region of FliK in substrate specificity switching of the bacterial flagellar type III export apparatus

作者：Kinoshita Miki; Aizawa Shin Ichi; Inoue Yumi; Namba Keiichi; Minamino Tohru

来源：Molecular Microbiology, 2017, 105(4): 572-588.

DOI：10.1111/mmi.13718

The bacterial flagellar export switching machinery consists of a ruler protein, FliK, and an export switch protein, FlhB and switches substrate specificity of the flagellar type III export apparatus upon completion of hook assembly. An interaction between the C-terminal domain of FliK (FliK(C)) and the C-terminal cytoplasmic domain of FlhB (FlhB(C)) is postulated to be responsible for this switch. FliK(C) has a compactly folded domain termed FliK(T3S4) (residues 268-352) and an intrinsically disordered region composed of the last 53 residues, FliK(CT) (residues 353-405). Residues 301-350 of FliK(T3S4) and the last five residues of FliK(CT) are critical for the switching function of FliK. FliK(CT) is postulated to regulate the interaction of FliK(T3S4) with FlhB(C), but it remains unknown how. Here we report the role of FliK(CT) in the export switching mechanism. Systematic deletion analyses of FliK(CT) revealed that residues of 351-370 are responsible for efficient switching of substrate specificity of the export apparatus. Suppressor mutant analyses showed that FliK(CT) coordinates FliK(T3S4) action with the switching. Site-directed photo-cross-linkin

• 出版日期2017-8
• 单位RIKEN