Bacterial gliding motility powered by helical transport of cell surface proteins
Mei-Hsien Tu1*, Hirofumi Wada2, Hsuan-Yi Chen1
1Department of Physics, National Central University, Jungli, Taiwan
2Department of Physical Sciences, Ritsumeikan University, Kyoto, Japan
* presenting author:MeiHsien Tu,
Motility is essential for microbes to survive in various environment, and some bacteria can achieve a directed motion on a solid surface by gliding which does not involve any moving appendages. Recent observation of high-resolution fluorescence microscopy has revealed that Flavobacterium johnsoniae is driven by surface adhesive proteins SprB and exhibits fast gliding motility at speeds of 1-3 μm/s [1]. While the rapid migration of adhesin SprB along a helical track on the cell surface leads to F. johnsoniae gliding, the nature of motors that propel the adhesins has remained a puzzle. A simple, one-dimensional theory consisting of stochastic binding dynamics and the translation of adhesive proteins along a cell's long axis has been previously proposed and explored the effect of spontaneous symmetry breaking on the bidirectional cell motion as well as the distinct behaviours of the moving cell in different velocity of those travelling adhesins [2]. In this work, the 1D model is now extended to a 3D theoretical framework where the helical geometry of the SprB's trajectory is also taken into consideration. The investigation begins with an analytic expression of the helical loop track, followed by quantitative procedures that will estimate translational velocity and angular velocity of the cell by solving force- and torque-balance conditions. The simulation emphasises that both translation and rotation of the cell body are due to the helical transport of the surface adhesive proteins.

[1] D. Nakane, K. Sato, H. Wada, M. J. McBride and K. Nakayama, Proc. Natl. Acad. Sci., 110, 11145 (2013)
[2] H. Wada, D. Nakane, and H.-Y. Chen, Phys. Rev. Lett. 111, 248102 (2013)

Keywords: gliding motility