POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
POSTERS - BLAST X - University of Utah
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<strong>BLAST</strong> X Poster #51<br />
CRYOEM STRUCTURE OF THE HOOK-FILAMENT JUNCTION OF SALMONELLA<br />
Fumiaki Makino (1), Takayuki Kato (1), Keiichi Namba (1)<br />
1: Grad. Sch. <strong>of</strong> Frontier Biosci., Osaka Univ.<br />
The bacterial flagellum is a biological nanomachine for the locomotion <strong>of</strong> bacteria. The<br />
flagellum consists <strong>of</strong> three functional parts: the basal body as a rotary motor, the filaments as a<br />
helical propeller, and the hook as a universal joint that connects the above-mentioned two parts.<br />
The filament is a tubular structure made <strong>of</strong> a single protein, FliC. It transforms into various<br />
helical forms in response to mechanical perturbation by reversal <strong>of</strong> motor rotation. The hook is<br />
also a tubular structure made <strong>of</strong> a single protein, FlgE, but is more flexible than the filament,<br />
allowing it to transmit motor torque to the filament regardless <strong>of</strong> its orientation. The hookfilament<br />
junction made <strong>of</strong> two proteins, FlgK and FlgL, connects these two mechanically distinct<br />
structures. It works as a mechanical adapter, allowing the two parts to go through dynamic<br />
conformational changes independently. To understand the adapter mechanism, we have<br />
analyzed the structure <strong>of</strong> the hook-filament junction by electron cryomicroscopy (cryoEM). We<br />
needed a Salmonella strain that produces short filaments for efficient data collection. We used a<br />
strain, MMC1660, which produces short filament due to a significantly low efficiency <strong>of</strong> FliC<br />
expression controlled by the addition <strong>of</strong> tetracycline. We established a procedure to purify the<br />
hook-basal body with short filament, collected cryoEM images and carried out image analysis.<br />
We will show the cryoEM structure <strong>of</strong> the hook-filament junction complex.<br />
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