Most mycoplasma species with polarized cell morphologies exhibit gliding motility, a process inextricably intertwined with adherence to host cells (cytadherence) but of uncertain molecular mechanism. Moreover, different phylogenetic groups of mycoplasmas appear to adhere and glide by different mechanisms. Mycoplasma penetrans, an organism found principally in HIV-positive patients in whom it appears to potentiate the progress of AIDS by promoting proliferation of the type of cell that HIV infects, also exhibits polar morphology and is known to burrow into host epithelial cells. However, the molecular basis for its interaction with host cells is entirely unknown, its genome sequence indicating an absence of homologs of cytadherence proteins of other organisms. Preliminary data indicate that M. penetrans, like other polarized mycoplasmas, exhibits gliding motility in vitro, its speed relating to the degree to which its colonies adsorb erythrocytes (hemadsorb), suggesting that in this species, cytadherence and gliding are also related. We will characterize the gliding motility of a fast-gliding strain and a slow-gliding strain by time-lapse microcinematography with respect to speed and optimal gliding conditions, including experiments aimed at identifying the energy source for M. penetrans gliding. We will characterize the gliding ability of both already-existing hemadsorption (HA) mutants as well as new HA mutants that we generate and select in order to further investigate the relationship between cytadherence and gliding motility in M. penetrans. We will use two-dimensional polyacrylamide gel electrophoresis and mass spectrometry to identify proteins that are absent or altered in these mutants as candidates for involvement in cytadherence and/or gliding motility. We will raise antisera against these proteins to begin studies of how they function in these processes, using the antibodies both as inhibitors of function and as tools to analyze subcellular localization and stability in both the parent strain and the mutant strains. The results of these experiments will reveal a novel molecular mechanism for cellular propulsion that might ultimately lead to rational design of therapeutics and might also be useful in the development of nanotechnological machines. ? ?
