期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：44
页码：15752-15755
DOI：10.1073/pnas.1418548111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe behavior of the flagellar rotary motor was monitored by following the rotation of small gold particles attached to flagellar hooks, nanometer-sized components found at the ends of motor drive shafts, providing an accurate readout of motor function. Some measurements were made in the past with large markers on flagellar filaments that suggested the presence of hidden steps preceding switching events. These steps were probably filament polymorphic transformations. Our data argue for a simple two-state system with transitions between clockwise and counterclockwise states that occur at random times. Switching dynamics of flagellar motors of Escherichia coli is commonly observed through markers attached to the flagellar filaments. To eliminate possible complications resulting from the conformational transitions of these filaments and to look at the output of motors more directly, we monitored motor rotation by attaching nanogold spheres to the hooks of cells lacking filaments. We observed exponentially distributed counterclockwise (CCW) and clockwise (CW) intervals and Lorentzian power spectra of the switching time series consistent with models that treat motor switching as a two-state Poisson process.
关键词：motility ; molecular motor ; switch ; nanogold
