Gliding ghosts of Mycoplasma mobile

Several species of mycoplasmas glide on solid surfaces, in the direction of their membrane protrusion at a cell pole, by an unknown mechanism. Our recent studies on the fastest species, Mycoplasma mobile, suggested that the gliding machinery, localized at the base of the membrane protrusion (the neck), is composed of two huge proteins. This machinery forms spikes sticking out from the neck and propels the cell by alternately binding and unbinding the spikes to a solid surface. Here, to study the intracellular mechanisms for gliding, we established a permeabilized gliding ghost model, analogous to the Triton model of the eukaryotic axoneme. Treatment with Triton X-100 stopped the gliding and converted the cells to permeabilized ghosts. When ATP was added exogenously, approximate to 85% of the ghosts were reactivated, gliding at speeds similar to those of living cells. The reactivation activity and inhibition by various nucleoticles and ATP analogs, as well as their kinetic parameters, showed that the machinery is driven by the hydrolysis of ATP to ADP plus phosphate, caused by an unknown ATPase.