DISTRIBUTION AND IMMUNOCYTOCHEMICAL LOCALIZATION OF TUBULIN-LIKE PROTEINS IN SPIROCHETES

Two proteins, S1 and S2 (45 and 65 kD) were selectively enriched by temperature-dependent cycling from Spirochaeta bajacaliforniensis. S1 was found to be immunoreactive with anti-brain tubulin antiserum using immunoblot techniques. S1 was found in other members of the genus Spirochaeta but not in Treponema or Spiroplasma. The pelleted material contains fibers as observed by light and electron microscopy. S1 and S2 were purified from Spirochaeta bajacaliforniensis and antibodies against S1 and S2 were raised in rabbits. The specificity of the antibodies to the antigens was demonstrated by immunoblotting. The anti-S1 and anti-S2 antisera crossreact with both S1 and S2 proteins. Anti-S1 antibodies bound weakly or not at all to freshly aggregated fibers but bound strongly to previously frozen fibers. Anti-S2 bound strongly to fibers either freshly formed or previously frozen. The anti-tubulin antisera which bound to S1 also bound to fresh and previously frozen fibers. Both anti-S1 and anti-S2 antibodies bound whole cells of Spirochaeta bajacaliforniensis along their entire length if the cells were ruptured by deoxycholate. The antibodies do not bind spirochete flagella but to material associated with the flagella that was liberated by treatment with deoxycholate. These findings suggest that both S1 and S2 proteins are part of the in vitro aggregated fibers and that these proteins are located along the entire length of the cell.