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Conformational spread as a mechanism for cooperativity in the bacterial flagellar switch

By F Bai, R W Branch, D. V. Nicolau jr, T Pilizota, B C Steele, P. K. Maini and R M Berry


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

Topics: Biology and other natural sciences
Publisher: AAAS
DOI identifier: 10.1126/science.1182105
OAI identifier:

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