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bioRxiv · 10.1101/2025.02.07.637169

Structural basis of flagellar rod assembly on the FliPQR protein-export channel

Kinoshita, M.·Miyata, T.·Makino, F.·Imada, K.·Namba, K.·Minamino, T.
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Abstract

The FliPQR complex constitutes a channel for export of the bacterial flagellar proteins involved in axial structure assembly. It also serves as a template for flagellar rod assembly. A periplasmic gate, formed by the N-terminal -helices of FliP and FliR, remains closed until FliE assembles onto FliP and FliR. The mechanism by which FliE opens the gate and assembles has remained unclear. Here, we present a cryoEM structure of the FliPQR complex in closed form at 3.0 [A] resolution. A {beta}-cap formed by the N-terminal {beta}-strands of FliP and FliR creates a tight seal in the closed gate. Interaction of FliE with FliP and FliR induces a conformational change in FliP and FliR, with their N-terminal -helices move up and outward. Consequently, the N-terminal {beta}-strands of FliP and FliR start opening the periplasmic gate one after another and form a docking site for FliE to initiate rod assembly.

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Kinoshita, M., Miyata, T., Makino, F., Imada, K., Namba, K., Minamino, T.. 2025-02-08. Structural basis of flagellar rod assembly on the FliPQR protein-export channel. https://doi.org/10.1101/2025.02.07.637169

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