Protein synthesis by Treponema pallidum extracted from infected rabbit tissue.

Virulent Treponema pallidum organisms, extracted from infected rabbit testes, incorporated amino acids into protein. A temperature of 34 C and a pH of 7.6 were optimal for protein synthesis, which was linear during in vitro incubation for 24 h. Selective inhibition of protein synthesis by erythromycin as judged by the incorporation of radiolabeled amino acids and radioautography demonstrated that treponemes were actively synthesizing proteins. Since addition of various sera and ultrafiltrates to the basal incubation mixture did not stimulate the level of protein synthesis, it was uncertain whether treponemes synthesized protein at a maximal or endogenous rate. Based upon the size of the unlabeled amino acid pool contained in infected testicular extract, it appeared that virulent treponemes utilized the majority of amino acids for protein synthesis but at varying efficiency.