Detailed Analyses of Stall Force Generation in Mycoplasma mobile Gliding |
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Authors: | Masaki Mizutani Isil Tulum Yoshiaki Kinosita Takayuki Nishizaka Makoto Miyata |
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Institution: | 1. Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan;2. The OCU Advanced Research Institute for Natural Science and Technology, Osaka City University, Sumiyoshi-ku, Osaka, Japan;3. Department of Physics, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo, Japan |
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Abstract: | Mycoplasma mobile is a bacterium that uses a unique mechanism to glide on solid surfaces at a velocity of up to 4.5 μm/s. Its gliding machinery comprises hundreds of units that generate the force for gliding based on the energy derived from ATP; the units catch and pull sialylated oligosaccharides fixed to solid surfaces. In this study, we measured the stall force of wild-type and mutant strains of M. mobile carrying a bead manipulated using optical tweezers. The strains that had been enhanced for binding exhibited weaker stall forces than the wild-type strain, indicating that stall force is related to force generation rather than to binding. The stall force of the wild-type strain decreased linearly from 113 to 19 picoNewtons after the addition of 0–0.5 mM free sialyllactose (a sialylated oligosaccharide), with a decrease in the number of working units. After the addition of 0.5 mM sialyllactose, the cells carrying a bead loaded using optical tweezers exhibited stepwise movements with force increments. The force increments ranged from 1 to 2 picoNewtons. Considering the 70-nm step size, this small-unit force may be explained by the large gear ratio involved in the M. mobile gliding machinery. |
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Keywords: | Corresponding author |
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