title: Uncovering the mechanism of trapping and cell orientation during Neisseria gonorrhoeae twitching motility.
abstract: Neisseria gonorrheae bacteria are the causative agent of the second most common sexually transmitted infection in the world. The bacteria move on a surface by means of twitching motility. Their movement is mediated by multiple long and flexible filaments, called type IV pili, that extend from the cell body, attach to the surface, and retract, thus generating a pulling force. Moving cells also use pili to aggregate and form microcolonies. However, the mechanism by which the pili surrounding the cell body work together to propel bacteria remains unclear. Understanding this process will help describe the motility of N. gonorrheae bacteria, and thus the dissemination of the disease which they cause. In this article we track individual twitching cells and observe that their trajectories consist of alternating moving and pausing intervals, while the cell body is preferably oriented with its wide side toward the direction of motion. Based on these data, we propose a model for the collective pili operation of N. gonorrheae bacteria that explains the experimentally observed behavior. Individual pili function independently but can lead to coordinated motion or pausing via the force balance. The geometry of the cell defines its orientation during motion. We show that by changing pili substrate interactions, the motility pattern can be altered in a predictable way. Although the model proposed is tangibly simple, it still has sufficient robustness to incorporate further advanced pili features and various cell geometries to describe other bacteria that employ pili to move on surfaces.
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts.
authors.forename: Vasily
authors.initials: V
authors.lastname: Zaburdaev
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York; Department of Biology, Brooklyn College, New York, New York.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Biais
authors.affiliation: Insitut für Theoretische Physik: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schmiedeberg
authors.affiliation: Department of Microbiology, Oslo University Hospital, Oslo, Norway.
authors.forename: Jens
authors.initials: J
authors.lastname: Eriksson
authors.affiliation: Department of Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors.forename: Ann-Beth
authors.initials: AB
authors.lastname: Jonsson
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Sheetz
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department of Physics, Harvard University, Cambridge, Massachusetts. Electronic address: weitz@seas.harvard.edu.
authors.forename: David A
authors.initials: DA
authors.lastname: Weitz
mesh_terms: D001696:Biomechanical Phenomena; D010861:Fimbriae, Bacterial / Q000378:metabolism; D008954:Models, Biological; D009068:Movement; D009344:Neisseria gonorrhoeae / Q000166:cytology*; D011336:Probability