National Institutes of Health/John E. Fogarty International Center (NIH/FIC)
GM61606
米国
引用
ジャーナル: PLoS One / 年: 2023 タイトル: CryoEM structure of a post-assembly MS-ring reveals plasticity in stoichiometry and conformation. 著者: Prashant K Singh / Gary Cecchini / Terunaga Nakagawa / T M Iverson / 要旨: The flagellar motor supports bacterial chemotaxis, a process that allows bacteria to move in response to their environment. A central feature of this motor is the MS-ring, which is composed entirely ...The flagellar motor supports bacterial chemotaxis, a process that allows bacteria to move in response to their environment. A central feature of this motor is the MS-ring, which is composed entirely of repeats of the FliF subunit. This MS-ring is critical for the assembly and stability of the flagellar switch and the entire flagellum. Despite multiple independent cryoEM structures of the MS-ring, there remains a debate about the stoichiometry and organization of the ring-building motifs (RBMs). Here, we report the cryoEM structure of a Salmonella MS-ring that was purified from the assembled flagellar switch complex (MSC-ring). We term this the 'post-assembly' state. Using 2D class averages, we show that under these conditions, the post-assembly MS-ring can contain 32, 33, or 34 FliF subunits, with 33 being the most common. RBM3 has a single location with C32, C33, or C34 symmetry. RBM2 is found in two locations with RBM2inner having C21 or C22 symmetry and an RBM2outer-RBM1 having C11 symmetry. Comparison to previously reported structures identifies several differences. Most strikingly, we find that the membrane domain forms 11 regions of discrete density at the base of the structure rather than a contiguous ring, although density could not be unambiguously interpreted. We further find density in some previously unresolved areas, and we assigned amino acids to those regions. Finally, we find differences in interdomain angles in RBM3 that affect the diameter of the ring. Together, these investigations support a model of the flagellum with structural plasticity, which may be important for flagellar assembly and function.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277.15 K / 装置: FEI VITROBOT MARK IV 詳細: Purified MS-rings were added to each grid at 277.15K at 100% humidity. After 30 sec of incubation, blotting was performed for 12 sec. The grid was then plunged into liquid ethane using a ...詳細: Purified MS-rings were added to each grid at 277.15K at 100% humidity. After 30 sec of incubation, blotting was performed for 12 sec. The grid was then plunged into liquid ethane using a Vitrobot Mark IV system (Thermo Fisher).
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
撮影
フィルム・検出器のモデル: FEI FALCON III (4k x 4k) 平均電子線量: 50.0 e/Å2