Behaviors and Energy Source ofMycoplasma gallisepticumGliding

Abstract

Mycoplasma gallisepticum, an avian-pathogenic bacterium, glides on host tissue surfaces by using a common motility system with Mycoplasma pneumoniae. In the present study, we observed and analyzed the gliding behaviors of M. gallisepticum in detail by using optical microscopes. M. gallisepticum glided at a speed of 0.27 ± 0.09 µm/s with directional changes relative to the cell axis of 0.6 ± 44.6 degrees/5 s without the rolling of the cell body. To examine the effects of viscosity on gliding, we analyzed the gliding behaviors under viscous environments. The gliding speed was constant in various concentrations of methylcellulose but was affected by Ficoll. To investigate the relationship between binding and gliding, we analyzed the inhibitory effects of sialyllactose on binding and gliding. The binding and gliding speed sigmoidally decreased with sialyllactose concentration, indicating the cooperative binding of the cell. To determine the direct energy source of gliding, we used a membrane-permeabilized ghost model. We permeabilized M. gallisepticum cells with Triton X-100 or Triton X-100 containing ATP and analyzed the gliding of permeabilized cells. The cells permeabilized with Triton X-100 did not show gliding; in contrast, the cells permeabilized with Triton X-100 containing ATP showed gliding at a speed of 0.014 ± 0.007 μm/s. These results indicate that the direct energy source for the gliding motility of M. gallisepticum is ATP.IMPORTANCEMycoplasmas, the smallest bacteria, are parasitic and occasionally commensal. Mycoplasma gallisepticum is related to human pathogenic Mycoplasmas—Mycoplasma pneumoniae and Mycoplasma genitalium—which causes so-called ‘walking pneumonia’ and non-gonococcal urethritis, respectively. These Mycoplasmas trap sialylated oligosaccharides, which are common targets among influenza viruses, on host trachea or urinary tract surfaces and glide to enlarge the infected areas. Interestingly, this gliding motility is not related to other bacterial motilities or eukaryotic motilities. Here, we quantitatively analyze cell behaviors in gliding and clarify the direct energy source. The results provide clues for elucidating this unique motility mechanism.

Force and stepwise movements of gliding motility in human pathogenic bacterium Mycoplasma pneumoniae

“…4). This observation is consistent with previous data; that is, the inhibition of binding by monoclonal antibodies decreased the gliding speed of M. pneumoniae (35), and the inhibition by SL decreased the speed of M. gallisepticum, coinciding with the common mechanism with M. pneumoniae (23). The decrease in speed was probably caused by the drag force generated from the substrate surface, because the friction force exerted from water is estimated to be more than 5000 times smaller than the stall force of 24 pN (Fig.…”

“…M. mobile glides up to 4.0 μm/s by a mechanism unrelated to that of M. pneumoniae . Previously, we measured the stall force of M. mobile gliding using optical tweezers to be approximately 113 pN (23). The stall forces of M. pneumoniae gliding were 23.7 ± 6.3 and 19.7 ± 5.3 pN in M129 and FH strains, respectively (Fig.…”

“…1B) (16)(17)(18)(19)(20). The model for gliding called the "Inchworm model" or "Double-spring hybrid ratchet model" is proposed, in which cells repeat the extensions and contractions of the attachment organelle based on the energy from ATP hydrolysis to enable smooth gliding (15,(21)(22)(23). Generally, the mechanical characteristics and detailed analysis of movements are essential for creating and completing a detailed model for the motility mechanism.…”

Isolation and structure of the fibril protein, a major component of the internal ribbon forSpiroplasmaswimming

“…Therefore, the energy for swimming should also be supplied by ATP, rather than the membrane potential, because the energy required for growth is supplied by ATP, which is produced by glycolysis in Spiroplasma. In fact, the two motility mechanisms of Mollicutes genus, Mycoplasma mobile-type and Mycoplasma pneumoniae-type gliding mechanisms depend on the hydrolytic energy of ATP (28)(29)(30)(31). The fibril protein derived from the MTA/SAH nucleosidase is unlikely to have ATPase activity, and no ATPase activity was detected in the fibril fraction.…”

ATP dependent polymerization dynamics of bacterial actin proteins involved inSpiroplasmaswimming

“…For Spiroplasma swimming, ATP is likely the energy source, because the membrane potential of Spiroplasma is -68 mV, much less than that of walled bacteria having flagella motors (-150 mV), which are driven by proton motive force (49)(50)(51). In fact, the gliding motility of two Mycoplasma species, belonging to the class Mollicutes as well as Spiroplasma, are driven by ATP (52,53). Fibril, one of the main components of the ribbon, does not have ATPase activity (18).…”