Native flagellar MS ring is formed by 34 subunits with 23-fold and 11-fold subsymmetries
Journal | Nat. Commun. 12:4223 (2021) |
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Title | Native flagellar MS ring is formed by 34 subunits with 23-fold and 11-fold subsymmetries |
Laboratory | JEOL YOKOGUSHI Research Alliance Laboratories〈SA Prof. NAMBA Keiichi〉 |
Abstract
The bacterial flagellar MS ring is a transmembrane complex acting as the core of the flagellar motor and template for flagellar assembly. The C ring attached to the MS ring is involved in torque generation and rotation switch, and a large symmetry mismatch between these two rings has been a long puzzle, especially with respect to their role in motor function. Here, using cryoEM structural analysis of the flagellar basal body and the MS ring formed by full-length FliF from Salmonella enterica, we show that the native MS ring is formed by 34 FliF subunits with no symmetry variation. Symmetry analysis of the C ring shows a variation with a peak at 34-fold, suggesting flexibility in C ring assembly. Finally, our data also indicate that FliF subunits assume two different conformations, contributing differentially to the inner and middle parts of the M ring and thus resulting in 23- and 11-fold subsymmetries in the inner and middle M ring, respectively. The internal core of the M ring, formed by 23 subunits, forms a hole of the right size to accommodate the protein export gate.
Authors | Akihiro Kawamoto (1, 2), Tomoko Miyata (1), Fumiaki Makino (1, 3), Miki Kinoshita (1), Tohru Minamino (1), Katsumi Imada (4), Takayuki Kato (1, 2), Keiichi Namba (1, 5, 6)
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PubMed | 34244518 |