Conformational spread as a mechanism for cooperativity in the bacterial flagellar switch.
The bacterial flagellar switch that controls the direction of flagellar rotation during chemotaxis has a highly cooperative response. This has previously been understood in terms of the classic two-state, concerted model of allosteric regulation. Here, we used high-resolution optical microscopy to observe switching of single motors and uncover the stochastic multistate nature of the switch. Our observations are in detailed quantitative agreement with a recent general model of allosteric cooperativity that exhibits conformational spread--the stochastic growth and shrinkage of domains of adjacent subunits sharing a particular conformational state. We expect that conformational spread will be important in explaining cooperativity in other large signaling complexes.
Bai
Fan
F
Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
Branch
Richard W
RW
Nicolau
Dan V
DV
Pilizota
Teuta
T
Steel
Bradley C
BC
Maini
Philip K
PK
Berry
Richard M
RM
D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005407:Flagella / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008954:Models, Biological; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism*; D009010:Monte Carlo Method; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction; D013816:Thermodynamics
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C077389:FliN protein, Bacteria; C075660:Flig protein, Bacteria; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D020409:Molecular Motor Proteins; D021122:Protein Subunits; C066821:FliM protein, Bacteria