7d84

Publication Abstract from PubMed

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.

Native flagellar MS ring is formed by 34 subunits with 23-fold and 11-fold subsymmetries.,Kawamoto A, Miyata T, Makino F, Kinoshita M, Minamino T, Imada K, Kato T, Namba K Nat Commun. 2021 Jul 9;12(1):4223. doi: 10.1038/s41467-021-24507-9. PMID:34244518^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.