Abstract
ABSTRACTMycoplasma 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.
Highlights
Mycoplasma species, the smallest bacteria, are parasitic and occasionally commensal, with small genomes that lack genes encoding a peptidoglycan layer [1, 2]
We have identified the internal structure of the machinery, named the “jellyfish” structure, which consists of a bell shape at the cell front connected by dozens of tentacular strands comprised of 20-nm particles at 30-nm intervals, as well as the component proteins of the machinery [27, 28], the direct energy source used [29, 30], the direct binding target [31,32,33], and the unitary steps of the movements [34]
To examine the directionality of binding, we designed an experiment, illustrated in Fig. 1C, in which an M. mobile cell stopped by starvation on a glass surface covered with sialylated oligosaccharides (SOs) was attached to a 1.5-m-diameter bead at the front or back end of the cell through avidin-biotin interaction
Summary
Mycoplasma species, the smallest bacteria, are parasitic and occasionally commensal, with small genomes that lack genes encoding a peptidoglycan layer [1, 2]. On the basis of these results, we proposed a working model, called the centipede or powerstroke model, where cells are propelled by flexible “legs” composed of Gli349 that, through repeated cycles, catch, pull, and release sialylated oligosaccharides (SOs) fixed on the glass surface via the distal “feet” [3, 5,6,7, 35] This working model is based on an assumption that the leg, plausibly Gli349, detaches more when it is pulled forward than backward [3, 6, 35]. We measured the force and the cell interaction lifetime for detachment of starved M. mobile cells from SOs fixed on a glass surface and concluded that detachment can occur more forward than backward
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
