Gliding Direction of Mycoplasma mobile

Abstract

Mycoplasma mobile glides in the direction of its cell pole by a unique mechanism in which hundreds of legs, each protruding from its own gliding unit, catch, pull, and release sialylated oligosaccharides fixed on a solid surface. In this study, we found that 77% of cells glided to the left with a change in direction of 8.4°؎ 17.6°m؊1 displacement. The cell body did not roll around the cell axis, and elongated, thinner cells also glided while tracing a curved trajectory to the left. Under viscous conditions, the range of deviation of the gliding direction decreased. In the presence of 250 M free sialyllactose, in which the binding of the legs (i.e., the catching of sialylated oligosaccharides) was reduced, 70% and 30% of cells glided to the left and the right, respectively, with changes in direction of ϳ30°m ؊1 . The gliding ghosts, in which a cell was permeabilized by Triton X-100 and reactivated by ATP, glided more straightly. These results can be explained by the following assumptions based on the suggested gliding machinery and mechanism: (i) the units of gliding machinery may be aligned helically around the cell, (ii) the legs extend via the process of thermal fluctuation and catch the sialylated oligosaccharides, and (iii) the legs generate a propulsion force that is tilted from the cell axis to the left in 70% and to the right in 30% of cells. IMPORTANCEMycoplasmas are bacteria that are generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide. Although these species appear to consistently glide in the direction of the protrusion, their exact gliding direction has not been examined. This study analyzed the gliding direction in detail under various conditions and, based on the results, suggested features of the machinery and the mechanism of gliding. Mycoplasmas are parasitic and occasionally commensal bacteria that have small genomes and lack a peptidoglycan layer (1, 2). Several Mycoplasma species form membrane protrusions, such as the head-like structure in Mycoplasma mobile (3, 4) and the attachment organelle in the human pathogen Mycoplasma pneumoniae (3-6). On solid surfaces, these species exhibit gliding motility in the direction of the protrusion, and this motility appears to be involved in the parasitism of mycoplasmas. Interestingly, mycoplasmas have no flagella or pili, and their genomes contain no genes related to known bacterial motility. In addition, no homologs of motor proteins that are common in eukaryotic motility have been found (7,8).M. mobile, isolated from the gills of a freshwater fish, is a fastgliding mycoplasma. It glides smoothly and continuously on glass at an average speed of 2.0 to 4.5 m s Ϫ1 , or 3 to 7 times the length of the cell per second, exerting a force of up to 27 pN (9-12). The gliding machinery formed at the base of the membrane protrusion can be divided into internal and surface structures. The internal, "jellyfish" structure is composed of ϳ10 proteins (13,14). The surface structure is ...

Behaviors and Energy Source ofMycoplasma gallisepticumGliding

“…5A) (37), and the average gliding direction was 0.6 ± 44.6 degrees/5 s (Fig. 1D), which is consistent with previous observations (23, 41). However, cells sometimes glided to the left or the right (Fig.…”

“…1B and C), which is consistent with those reported in the previous study (37). To analyze the gliding direction, we traced the angles between the cell axis and the following gliding direction for 60 s at 5 s intervals, as previously described (41). The averaged gliding direction relative to the cell axis was 0.6 ± 44.6 degrees/5 s (n = 231) (Fig.…”

“…A previous study shows that M. mobile gliding is drastically inhibited by viscous environments created using methylcellulose (MC) or Ficoll (41). To examine the effects of viscosity on M. gallisepticum gliding, we analyzed the gliding behaviors under viscous buffers including MC or Ficoll.…”

Refined mechanism ofMycoplasma mobilegliding based on structure, ATPase activity, and sialic acid binding of machinery

“…(b) Foot, the distal domain of Gli349 has binding activity to SOs (31). (c) Gliding is driven by strokes 70 nm long, 1.5 pN in force, and its direction is slightly tilted from the cell axis (7, 27, 28, 32). (d) The propelling force is used also to detach foot from SOs after stroke and foot generates drag before detach (15, 18, 34).…”

“…(f) ATP is required to detach foot from SOs, as shown by the gliding ghost experiments (29). (g) Foot catches SOs after thermal fluctuation with some cooperativity (32-34).…”