Related Experiment Video
Updated: Mar 8, 2026

Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
Co-Folding of a FliF-FliG Split Domain Forms the Basis of the MS:C Ring Interface within the Bacterial Flagellar
Michael J Lynch1, Robert Levenson2, Eun A Kim3
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Abstract:
The interface between the membrane (MS) and cytoplasmic (C) rings of the bacterial flagellar motor couples torque generation to rotation within the membrane. The structure of the C-terminal helices of the integral membrane protein FliF (FliFC) bound to the N terminal domain of the switch complex protein FliG (FliGN) reveals that FliGN folds around FliFC to produce a topology that closely resembles both the middle and C-terminal domains of FliG. The interface is consistent with solution-state nuclear magnetic resonance, small-angle X-ray scattering, in vivo interaction studies, and cellular motility assays. Co-folding with FliFC induces substantial conformational changes in FliGN and suggests that FliF and FliG have the same stoichiometry within the rotor. Modeling the FliFC:FliGN complex into cryo-electron microscopy rotor density updates the architecture of the middle and upper switch complex and shows how domain shuffling of a conserved interaction module anchors the cytoplasmic rotor to the membrane.
Related Concept Videos
Flagella and Motility in Bacteria
Mechanism of Filopodia Formation
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Fimbriae, Pili, and Axial Filaments
The Contractile Ring
A small GTPase, RhoA, controls the function and assembly of the contractile ring. RhoA belongs to the Ras superfamily of proteins. The activation of formins by RhoA promotes...
Generation of Straight or Branched Actin Filaments
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Cytoskeletal Proteins in Bacteria

