1. The FlgN chaperone activates the Na + -driven engine of the Salmonella flagellar protein export apparatus.
- Author
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Minamino T, Kinoshita M, Morimoto YV, and Namba K
- Subjects
- Bacterial Proteins genetics, Flagella genetics, Membrane Proteins genetics, Mutation, Protein Conformation, Protein Transport, Proton-Translocating ATPases genetics, Protons, Salmonella typhimurium genetics, Bacterial Proteins metabolism, Flagella metabolism, Membrane Proteins metabolism, Proton-Translocating ATPases metabolism, Salmonella typhimurium metabolism, Sodium metabolism
- Abstract
The bacterial flagellar protein export machinery consists of a transmembrane export gate complex and a cytoplasmic ATPase complex. The gate complex has two intrinsic and distinct H
+ -driven and Na+ -driven engines to drive the export of flagellar structural proteins. Salmonella wild-type cells preferentially use the H+ -driven engine under a variety of environmental conditions. To address how the Na+ -driven engine is activated, we analyzed the fliJ(Δ13-24) fliH(Δ96-97) mutant and found that the interaction of the FlgN chaperone with FlhA activates the Na+ -driven engine when the ATPase complex becomes non-functional. A similar activation can be observed with either of two single-residue substitutions in FlhA. Thus, it is likely that the FlgN-FlhA interaction generates a conformational change in FlhA that allows it to function as a Na+ channel. We propose that this type of activation would be useful for flagellar construction under conditions in which the proton motive force is severely restricted.- Published
- 2021
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