Arsenate was added to M. penetrans cells to determine whether ATP hydrolysis by a motor-associated component directly provides
energy for gliding, as proposed for M. mobile, upon whose gliding motility arsenate has an immediate negative impact (Jaffe et al., 2004). M. penetrans continued to glide GSK-3 beta pathway in the presence of 50 mM arsenate, five times the amount in which growth was prevented (see above), at incubation times ranging from 1 to 8 h. In 50 mM arsenate, the gliding speeds of both M. mobile [F(1, 144) = 13331, P < 0.0003] and M. penetrans [F(1, 144) = 7670, P < 0.0003] were significantly reduced. However, the 37% decrease in M. penetrans was much smaller than that in M. mobile, which exhibited an 89% decrease in speed (Fig. 2), essentially in agreement with the observations of an absence of M. mobile cells moving faster than 10% of normal gliding speed after 10 min under similar conditions (Jaffe et al., 2004). Although the change in speed of M. penetrans was statistically significant, the moderate value of the decrease and the continued movement of the cells after 8 h (not shown) suggest that direct inhibition of the motor by ATP depletion was unlikely. Increasing the arsenate concentration fivefold further, to 250 mM, had a negligible effect on M. penetrans motility (Fig. 2). Thus, ATP hydrolysis is an unlikely energy Small molecule library cell assay source for gliding by M. penetrans. The
presence of membrane potential has been reported in a variety of mycoplasma species (Benyoucef et al., 1981; Schiefer & Schummer, 1982). To determine whether PMF supplies the energy needed for M. penetrans gliding motility, we observed motility
in the presence of the ionophore CCCP, which collapses the proton gradient. Cells were incubated for 1 h in the presence of 10 mM CCCP in DMSO and in PBS-G2K containing the same volume of DMSO used in the test buffer. After 1 h, gliding speed actually increased by 29% compared to the control buffer (P < 0.0001) (Fig. 2), ruling out PMF as an energy source for gliding motility of M. penetrans. ADAMTS5 To test SMF as a potential energy source for M. penetrans gliding, cells were observed in the presence of amiloride, an inhibitor of Na+/H+ antiporters and sodium channels, which competes with Na+ in the medium (Benos, 1982). Mycoplasma penetrans gliding speed was not significantly affected by 1 h of incubation in amiloride (P = 0.6) (Fig. 2), ruling out SMF as an energy source. To determine the role of thermal energy in the motility mechanism of M. penetrans, we analyzed its gliding speed under conditions of differing temperature. If radiant energy from ambient heat is a significant power source, then we would predict increased speed even at temperatures in excess of those normally encountered physiologically. We analyzed gliding speed at temperatures ranging from 30 to 40 °C and pH levels ranging from 5.8 to 8.8 (Fig. 3). Speed increased with temperature, but at acidic or alkaline pH, the trend was less distinct.