A Mechanism of Modulating the Direction of Flagellar Rotation in Bacteria by Fumarate and Fumarate Reductase
| Autor: | Anna Koganitsky, Tali Dadosh, Michael Eisenbach, Dmitry Tworowski, Gary Cecchini |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Rotation
Protein subunit SDHA Flavoprotein Molecular Dynamics Simulation medicine.disease_cause Article 03 medical and health sciences 0302 clinical medicine Bacterial Proteins Fumarates Structural Biology medicine Animals Anaerobiosis Molecular Biology Escherichia coli Fluorescent Dyes 030304 developmental biology 0303 health sciences Bacteria biology Chemistry Succinate dehydrogenase Fumarate reductase Respiratory enzyme Succinate Dehydrogenase Flagella Docking (molecular) biology.protein Biophysics Cattle 030217 neurology & neurosurgery Protein Binding |
| Zdroj: | J Mol Biol |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/j.jmb.2019.08.001 |
| Popis: | Fumarate, an electron acceptor in anaerobic respiration of Escherichia coli, has an additional function of assisting the flagellar motor to shift from counterclockwise to clockwise rotation, with a consequent modulation of the bacterial swimming behavior. Fumarate transmits its effect to the motor via the fumarate reductase complex (FrdABCD), shown to bind to FliG — one of the motor’s switch proteins. How binding of the FrdABCD respiratory enzyme to FliG enhances clockwise rotation and how fumarate is involved in this activity, have remained puzzling. Here we show that the FrdA subunit in the presence of fumarate is sufficient for binding to FliG and for clockwise enhancement. We further demonstrate by in vitro binding assays and super-resolution microscopy in vivo that the mechanism by which fumarate-occupied FrdA enhances clockwise rotation involves its preferential binding to the clockwise state of FliG (FliG(cw)). Continuum electrostatics combined with docking analysis and conformational sampling endorsed the experimental conclusions and suggested that the FrdA-FliG(cw) interaction is driven by the positive electrostatic potential generated by FrdA and the negatively charged areas of FliG. They further demonstrated that fumarate changes FrdA’s conformation to one that can bind to FliG(cw). These findings also show that the reason for the failure of the succinate dehydrogenase flavoprotein SdhA (an almost-identical analog of FrdA shown to bind to FliG equally well) to enhance clockwise rotation is that it has no binding preference for FliG(cw). We suggest that this mechanism is physiologically important as it can modulate the magnitude of ΔG(0) between the clockwise and counterclockwise states of the motor to tune the motor to the growth conditions of the bacteria. |
| Databáze: | OpenAIRE |
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