title: Directed Binding of Gliding Bacterium, Mycoplasma mobile, Shown by Detachment Force and Bond Lifetime.
abstract: Mycoplasma mobile, a fish-pathogenic bacterium, features a protrusion that enables it to glide smoothly on solid surfaces at a velocity of up to 4.5 µm s(-1) in the direction of the protrusion. M. mobile glides by a repeated catch-pull-release of sialylated oligosaccharides fixed on a solid surface by hundreds of 50-nm flexible "legs" sticking out from the protrusion. This gliding mechanism may be explained by a possible directed binding of each leg with sialylated oligosaccharides, by which the leg can be detached more easily forward than backward. In the present study, we used a polystyrene bead held by optical tweezers to detach a starved cell at rest from a glass surface coated with sialylated oligosaccharides and concluded that the detachment force forward is 1.6- to 1.8-fold less than that backward, which may be linked to a catch bond-like behavior of the cell. These results suggest that this directed binding has a critical role in the gliding mechanism.
  
  
  
  Mycoplasma species are the smallest bacteria and are parasitic and occasionally commensal, as represented by Mycoplasma pneumoniae, which causes so-called "walking pneumonia" in humans. Dozens of species glide on host tissues, always in the direction of the characteristic cellular protrusion, by novel mechanisms. The fastest species, Mycoplasma mobile, catches, pulls, and releases sialylated oligosaccharides (SOs), which are common targets among influenza viruses, by means of a specific receptor based on the energy of ATP hydrolysis. Here, force measurements made with optical tweezers revealed that the force required to detach a cell from SOs is smaller forward than backward along the gliding direction. The directed binding should be a clue to elucidate this novel motility mechanism.
authors.affiliation: Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nakane
authors.affiliation: Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Mizutani
authors.affiliation: Department of Physics, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nishizaka
authors.affiliation: Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Sumiyoshi-ku, Osaka, Japan miyata@sci.osaka-cu.ac.jp.
authors.forename: Makoto
authors.identifier: 0000-0002-7478-7390
authors.initials: M
authors.lastname: Miyata
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites; D005399:Fishes / Q000382:microbiology; D005898:Glass / Q000737:chemistry*; D008124:Locomotion; D009174:Mycoplasma / Q000502:physiology*; D009844:Oligosaccharides / Q000737:chemistry* / Q000502:physiology; D052898:Optical Tweezers; D011137:Polystyrenes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D009844:Oligosaccharides; D011137:Polystyrenes