Open AccessMolecular mechanism for rotational switching of the bacterial flagellar motor
Author(s) -
Yifan Chang,
Kai Zhang,
Brittany L. Carroll,
Xiaowei Zhao,
Nyles W. Charon,
Steven J. Norris,
M. A. Motaleb,
Chunhao Li,
Jun Li
Publication year - 2020
Publication title -
nature structural and molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.448
H-Index - 270
eISSN - 1545-9993
pISSN - 1545-9985
DOI - 10.1038/s41594-020-0497-2
Subject(s) - rotation (mathematics) , molecular motor , torque , flagellum , mechanosensitive channels , biophysics , chemistry , generator (circuit theory) , physics , biology , biochemistry , computer science , receptor , quantum mechanics , artificial intelligence , power (physics) , ion channel , gene , thermodynamics
The bacterial flagellar motor can rotate in counterclockwise (CCW) or clockwise (CW) senses, and transitions are controlled by the phosphorylated form of the response regulator CheY (CheY-P). To dissect the mechanism underlying flagellar rotational switching, we use Borrelia burgdorferi as a model system to determine high-resolution in situ motor structures in cheX and cheY3 mutants, in which motors are locked in either CCW or CW rotation. The structures showed that CheY3-P interacts directly with a switch protein, FliM, inducing a major remodeling of another switch protein, FliG2, and altering its interaction with the torque generator. Our findings lead to a model in which the torque generator rotates in response to an inward flow of H + driven by the proton motive force, and conformational changes in FliG2 driven by CheY3-P allow the switch complex to interact with opposite sides of the rotating torque generator, facilitating rotational switching.