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The bacterial flagellar switch complex is getting more complex
Author(s) -
CohenBenLulu Galit N,
Francis Noreen R,
Shimoni Eyal,
Noy Dror,
Davidov Yaacov,
Prasad Krishna,
Sagi Yael,
Cecchini Gary,
Johnstone Rose M,
Eisenbach Michael
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.48
Subject(s) - biology , escherichia coli proteins , computational biology , bacterial protein , microbiology and biotechnology , genetics , bacteria
The mechanism of function of the bacterial flagellar switch, which determines the direction of flagellar rotation and is essential for chemotaxis, has remained an enigma for many years. Here we show that the switch complex associates with the membrane‐bound respiratory protein fumarate reductase (FRD). We provide evidence that FRD binds to preparations of isolated switch complexes, forms a 1:1 complex with the switch protein FliG, and that this interaction is required for both flagellar assembly and switching the direction of flagellar rotation. We further show that fumarate, known to be a clockwise/switch factor, affects the direction of flagellar rotation through FRD. These results not only uncover a new component important for switching and flagellar assembly, but they also reveal that FRD, an enzyme known to be primarily expressed and functional under anaerobic conditions in Escherichia coli , nonetheless, has important, unexpected functions under aerobic conditions.