| Autor: |
Kinosita Y; Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan. yoshiaki.kinosita@gmail.com.; Department of Physics, University of Oxford, Park load, Oxford, OX1 3PU, UK. yoshiaki.kinosita@gmail.com.; Molecular Physiology Laboratory, RIKEN, Wako, Japan. yoshiaki.kinosita@gmail.com., Ishida T; Department of Frontier Bioscience and Research Center for Micro-Nano Technology, Hosei University, Tokyo, 184-8584, Japan., Yoshida M; Department of Frontier Bioscience and Research Center for Micro-Nano Technology, Hosei University, Tokyo, 184-8584, Japan., Ito R; Department of Frontier Bioscience and Research Center for Micro-Nano Technology, Hosei University, Tokyo, 184-8584, Japan., Morimoto YV; Department of Physics and Information Technology, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka, Japan., Goto K; Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan., Berry RM; Department of Physics, University of Oxford, Park load, Oxford, OX1 3PU, UK., Nishizaka T; Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan., Sowa Y; Department of Frontier Bioscience and Research Center for Micro-Nano Technology, Hosei University, Tokyo, 184-8584, Japan. ysowa@hosei.ac.jp. |
| Abstrakt: |
Most motile bacteria are propelled by rigid, helical, flagellar filaments and display distinct swimming patterns to explore their favorable environments. Escherichia coli cells have a reversible rotary motor at the base of each filament. They exhibit a run-tumble swimming pattern, driven by switching of the rotational direction, which causes polymorphic flagellar transformation. Here we report a novel swimming mode in E. coli ATCC10798, which is one of the original K-12 clones. High-speed tracking of single ATCC10798 cells showed forward and backward swimming with an average turning angle of 150°. The flagellar helicity remained right-handed with a 1.3 μm pitch and 0.14 μm helix radius, which is consistent with the feature of a curly type, regardless of motor switching; the flagella of ATCC10798 did not show polymorphic transformation. The torque and rotational switching of the motor was almost identical to the E. coli W3110 strain, which is a derivative of K-12 and a wild-type for chemotaxis. The single point mutation of N87K in FliC, one of the filament subunits, is critical to the change in flagellar morphology and swimming pattern, and lack of flagellar polymorphism. E. coli cells expressing FliC(N87K) sensed ascending a chemotactic gradient in liquid but did not spread on a semi-solid surface. Based on these results, we concluded that a flagellar polymorphism is essential for spreading in structured environments. |
