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.
Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
Fan
F
Bai
Richard W
RW
Branch
Dan V
DV
Nicolau
Teuta
T
Pilizota
Bradley C
BC
Steel
Philip K
PK
Maini
Richard M
RM
Berry
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