ULTRASTRUCTURAL AND ENERGETIC ANALYSIS OF MOTILITY IN SPIROPLASMA FLORICOLA OBMG

Negatively stained preparations of whole cells revealed a characteristic helical morphology with a 1/2 wavelength distance of 0.60 (mu)m. No typical bacterial organelles of motility were detected such as flagella or axial filaments. Thin sections of optimally preserved specimens, showed the presence of a fibril band beneath the cytoplasmic membrane extending axially through the entire cell body. This fibril band measured 94 nm in diameter and the individual fibrils had a mean diameter of 4 nm. Bundles of fibrils were also observed in negatively stained preparations from detergent insoluble residues of whole cells and these isolated fibril bands were twisted at regular intervals corresponding to the distance between turns of the helix. Additionally fibrils were purified and the protein monomers were estimated to have a molecular weight of 55,000 by SDS-polyacrylamide gel electrophoresis. The exact function of these fibrils in motility awaits further investigation.; Energy metabolism related to the energetics of motility in S. floricola OBMG was also evaluated. The cells appear to contain an Embden-Meyerhof-Parnas catabolic pathway for oxidizing sugars and a truncated respiratory system consisting of a menaquinone and flavoprotein. Results indicate that both may be involved in ATP production. The energetics of motility was examined by employing various inhibitors and ionophores. Cells were completely immobilized by the ionophores valinomycin (which lowered (DELTA)(psi)) plus nigericin (which lowered (DELTA)pH) or CCCP (which abolishes (DELTA)p). These ionophores did not decrease cellular ATP concentrations. In addition, when cellular ATP concentrations were depleted by arsenate, motility was restored by adding pyruvate which stimulated 0(,2)-consumption. The pyruvate induced motility was also sensitive to CCCP inhibition. The results described above are consistent with the idea that motility is driven by proton motive force. Both a proton translocating ATPase and respiration appear to play a role in maintenance of a proton motive force in this spiroplasma.