Populational Heterogeneity vs. Temporal Fluctuation in Escherichia coli Flagellar Motor Switching |
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| Authors: | Fan Bai Yong-Suk Che Nobunori Kami-ike Qi Ma Tohru Minamino Yoshiyuki Sowa Keiichi Namba |
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| Institution: | †Biodynamic Optical Imaging Center and School of Life Sciences, Peking University, Beijing, People’s Republic of China;‡Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan;§Department of Frontier Bioscience, Hosei University, Tokyo, Japan;¶Research Center for Micro-Nano Technology, Hosei University, Tokyo, Japan |
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| Abstract: | The dynamic switching of the bacterial flagellar motor regulates cell motility in bacterial chemotaxis. It has been reported under physiological conditions that the switching bias of the flagellar motor undergoes large temporal fluctuations, which reflects noise propagating in the chemotactic signaling network. On the other hand, nongenetic heterogeneity is also observed in flagellar motor switching, as a large group of switching motors show different switching bias and frequency under the same physiological condition. In this work, we present simultaneous measurement of groups of Escherichia coli flagellar motor switching and compare them to long time recording of single switching motors. Consistent with previous studies, we observed temporal fluctuations in switching bias in long time recording experiments. However, the variability in switching bias at the populational level showed much higher volatility than its temporal fluctuation. These results suggested stable individuality in E. coli motor switching. We speculate that uneven expression of key regulatory proteins with amplification by the ultrasensitive response of the motor can account for the observed populational heterogeneity and temporal fluctuations. |
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