title: Mechanism for adaptive remodeling of the bacterial flagellar switch.
abstract: The bacterial flagellar motor has been shown in previous work to adapt to changes in the steady-state concentration of the chemotaxis signaling molecule, CheY-P, by changing the FliM content. We show here that the number of FliM molecules in the motor and the fraction of FliM molecules that exchange depend on the direction of flagellar rotation, not on CheY-P binding per se. Our results are consistent with a model in which the structural differences associated with the direction of rotation modulate the strength of FliM binding. When the motor spins counterclockwise, FliM binding strengthens, the fraction of FliM molecules that exchanges decreases, and the ring content increases. The larger number of CheY-P binding sites enhances the motor's sensitivity, i.e., the motor adapts. An interesting unresolved question is how additional copies of FliM might be accommodated.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Pushkar P
authors.initials: PP
authors.lastname: Lele
authors.forename: Richard W
authors.initials: RW
authors.lastname: Branch
authors.forename: Vedhavalli S J
authors.initials: VS
authors.lastname: Nathan
authors.forename: Howard C
authors.initials: HC
authors.lastname: Berg
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000502:physiology*; D029968:Escherichia coli Proteins; D005407:Flagella / Q000502:physiology*; D036681:Fluorescence Recovery After Photobleaching; D008565:Membrane Proteins / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008856:Microscopy, Fluorescence; D008956:Models, Chemical; D020409:Molecular Motor Proteins / Q000378:metabolism*; D011485:Protein Binding; D012399:Rotation
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D020409:Molecular Motor Proteins; C000607606:cheY protein, E coli; C066821:FliM protein, Bacteria