Chemotactic response of a gliding mycoplasma

Kirchhoff, H; Boldt, Ute; Rosengarten, Renate; Klein-Struckmeier, Anette

doi:10.1007/bf01577215

Cited by 16 publications

(7 citation statements)

References 10 publications

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“…While there have been many remarkable observations of gliding motility of M. mobile, the source of energy for this phenomenon has not been convincingly demonstrated (15,16,(28)(29)(30)(33)(34)(35). One study did examine the effects of various substances on M. mobile gliding (including some which overlap those discussed here), but that effort was directed at longerterm effects and did not specifically address the issue of ener- getics (31).…”

Section: Discussionmentioning

confidence: 99%

Energetics of Gliding Motility in Mycoplasma mobile

2004

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Mycoplasma mobile glides on surfaces at up to 7 m/s by an unknown mechanism. We studied the energetics that power gliding by using a novel, growth medium-free system. We found that cells could glide in defined media if the glass substrate is preconditioned by exposure to horse serum. The active component that potentiates gliding is sensitive to proteinase K treatment. We used the defined medium system to test the effect of various inhibitors, ionophores, and poisons on motility of M. mobile. Valinomycin, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), N,N-dicyclohexylcarbodiimide, phenamil, amiloride, rifampin, and puromycin had no short-term effects on gliding. We also confirmed that we were able to modulate the membrane potential with valinomycin and FCCP by using a potential-sensitive dye. Shifting the pH likewise had no effect on motility. These results rule out the use of conventional ion motive forces to power gliding. Arsenate had a dramatic inhibitory effect on gliding, and both the speed and the fraction of cells moving tracked ATP levels. Sodium orthovanadate had a slight but significant inhibitory effect on gliding. Taken together, these results suggest that the motor system of M. mobile is likely an ATPase or is directly coupled to an ATPase.While studies of locomotion in swimming bacteria are well advanced, investigations of gliding motility remain comparatively limited. Yet gliding motility, defined as a smooth translocation over a solid surface, is represented frequently throughout the eubacterial phylogenetic tree and in some instances has been associated with pathogenicity (25). Even several species of mycoplasmas, some of the simplest bacteria known in terms of size and genomic content, are known to perform gliding motility (14, 32).The mycoplasmas are wall-less bacteria characterized by small physical dimensions and genome sizes (32). Among the mycoplasmas, the fish pathogen Mycoplasma mobile demonstrates extremely robust gliding motility (16,34). M. mobile is one of the flask-shaped mycoplasmas (approximately 1.0 ϫ 0.3 m) and has a genome of approximately 780 kbp (4). It has always been observed to glide in the direction of the "head" (corresponding to the tapered end of the cell) without reversals or pauses at speeds of up to 7 m/s (34). It can tow an erythrocyte, roughly 10 times its size, without significant loss in speed and has been measured to exert up to 27 pN of force (28,33). Some recent progress at uncovering the molecular mechanism of gliding in M. mobile has been made, including localization of the gliding apparatus to the head region of its flasklike cell body and isolation of mutants with altered gliding phenotypes (29,30,41). However, little is known about the prerequisites or energy source for gliding in M. mobile.Flagellated bacteria use ion motive forces to power their flagellar motors. For instance, Escherichia coli uses a proton motive force (⌬p H ), while various Vibrio species use a sodium motive force (⌬p Na ) to drive their polar (but not lateral) flagella...

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Section: Discussionmentioning

confidence: 99%

Energetics of Gliding Motility in Mycoplasma mobile

2004

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“…Motile bacteria have chemosensory systems to control the direction of the movement (Bourret and Stock, 2002). However, no obvious homologues to bacterial chemotaxis or two component signal transduction genes have been found in the sequenced mycoplasma genomes, although chemotactic (Kirchhoff et al ., 1987) and rheotactic responses (Rosengarten et al ., 1988) have been described in M. mobile . In addition, specific mycoplasma genes involved in the regulation of gliding motion are not yet identified.…”

Section: Introductionmentioning

confidence: 99%

Deletion of the Mycoplasma genitalium MG_217 gene modifies cell gliding behaviour by altering terminal organelle curvature

Burgos

Pich

Querol

et al. 2008

Molecular Microbiology

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SummaryMotility is often a virulence factor of pathogenic bacteria. Although recent works have identified genes involved in gliding motility of mycoplasmas, little is known about the mechanisms governing the cell gliding behaviour. Here, we report that Mycoplasma genitalium MG217 is a novel protein involved in the gliding apparatus of this organism and it is, at least, one of the genes that are directing cells to move in narrow circles when they glide. In the absence of MG_217 gene, cells are still able to glide but they mainly move drawing erratic or wide circular paths. This change in the gliding behaviour correlates with a rearrangement in the terminal organelle disposition, suggesting that the terminal organelle operates as a guide to steer the mycoplasma cell in a specific direction. Immunogold labelling reveals that MG217 protein is located intracellular at the distal end of the terminal organelle, between the cell membrane and the terminal button. Such location is consistent with the idea that MG217 could act as a modulator of the terminal organelle curvature, allowing cells to move in specific directions.

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“…Despite its diminutive size and simple organization, Mycoplasma mobile 163K (3), which has been isolated from the gills of a freshwater fish (5), exhibits some peculiar properties: it has a differentiated cell shape with a specialized terminal structure (5,6), can attach strongly to glass and plastic as well as to animal cells (5,6), can glide with remarkably high speed on inert surfaces (6,8) and on erythrocytes (2), and exhibits chemotactic behavior in response to a range of attractants (4). The last property indicates that M. mobile is able to sense changes in concentrations of specific chemical substances and can consequently direct its motion in preferred directions.…”

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confidence: 99%

“…Exponentially growing cells were centrifuged for 5 min at 3,000 x g and resuspended in fresh culture medium at a concentration of approximately 108 CFU/ml. The gliding motion of M. mobile in fluid streams was investigated by a test procedure similar to that described for chemotaxis (4).…”

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Rheotactic behavior of a gliding mycoplasma

1988

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Mycoplasma mobile, a new gliding mycoplasma isolated from the gills of a fish, was capable of positive rheotaxis; the cells glided upstream in a moving fluid. To our knowledge this is the first demonstration of rheotactic behavior among the procaryotes.Despite its diminutive size and simple organization, Mycoplasma mobile 163K (3), which has been isolated from the gills of a freshwater fish (5), exhibits some peculiar properties: it has a differentiated cell shape with a specialized terminal structure (5, 6), can attach strongly to glass and plastic as well as to animal cells (5, 6), can glide with remarkably high speed on inert surfaces (6, 8) and on erythrocytes (2), and exhibits chemotactic behavior in response to a range of attractants (4). The last property indicates that M. mobile is able to sense changes in concentrations of specific chemical substances and can consequently direct its motion in preferred directions. Here we report another sensory-response system of this gliding mycoplasma. We found that M. mobile is also able to respond to the mechanical stimuli of flow velocity gradients by moving preferentially upstream.M. mobile was cultivated in modified Hayflick medium (4, 8). Exponentially growing cells were centrifuged for 5 min at 3,000 x g and resuspended in fresh culture medium at a concentration of approximately 108 CFU/ml. The gliding motion of M. mobile in fluid streams was investigated by a test procedure similar to that described for chemotaxis (4).Briefly, flow chambers were prepared by placing a glass cover slip (21 by 26 mm) over a 2-,ul drop of a freshly prepared mycoplasma cell suspension on a glass slide and sealing the 26-mm edges of the cover slip with paraffin. Before being sealed, the cover slip was firmly pressed to the slide to minimize the thickness of the liquid layer, thus allowing fresh medium to flow through from one open end of the chamber to the other by capillary action. The chambers were incubated for at least 5 min in petri dishes lined with dampened filter paper to allow the mycoplasma cells to establish contact either with the undersurface of the cover slip or with the top of the slide. This was important, since only attached cells exhibit gliding movement. The preparations were examined with a Zeiss photomicroscope equipped with Nomarski interference optics and coupled to a microcinematographic system, as well as with a Leitz photomicroscope equipped with dark-field optics. The microscope image was focused in the plane of the attached cells, and an appropriate observation field with an adequate number of gliding organisms (10 to 20 cells) was selected. A current velocity gradient across the chamber was induced by placing microdrops of medium along one open end of the chamber. While this technique did not generate a stable current velocity gradient along the direction of flow, it did permit the calculation of local current velocity values. Furthermore, it * Corresponding author. was possible to change the slope of the current velocity gradient and the absolute local ...

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Chemotactic response of a gliding mycoplasma

Cited by 16 publications

References 10 publications

Energetics of Gliding Motility in Mycoplasma mobile

Energetics of Gliding Motility in Mycoplasma mobile

Deletion of the Mycoplasma genitalium MG_217 gene modifies cell gliding behaviour by altering terminal organelle curvature

Rheotactic behavior of a gliding mycoplasma

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