STUDIES ON METABOLISM OF RICKETTSIAE II. INCORPORATION OF ¹⁴C AMINO ACID MIXTURE AND ³⁵S METHIONINE BY RICKETTSIA MOOSERI

Abstract

Various metabolic activities, independent of those of host cells, have been reported in some species of rickettsiae in vitro. These findings, though they contributed enough in differentiating rickettsiae from the category of virus, had been confined within exergonic reactions until Bovarnick (1959, 1960 a, b) reported the evidence of incorporation reactions in purified Rickettsia prowazeki.
An ability of purified Rickettsia mooseri to incorporate ³⁵S-methionine into its protein fraction in a medium lacking other complementary amino acids was evidenced by us (Fujita et al., 1959) .
In the present study, a protein specific incorporation of amino acid mixture uniformly labeled with ¹⁴C is reported together with the results on the ³⁵S-methionine incorporation. In contrast to the incorporation of ³⁵S-methionine, which is found not to be available as an estimation of protein synthesis, the incorporation of ¹⁴C amino acid mixture can be regarded as a rough estimation of protein synthesis taking place in a medium much simpler than that previously used by Bovarnick.
This incorporation of ¹⁴C was found to be able to couple with the phosphorylation of ATP, indicating that the oxidative phosphorylation reported by Bovarnick (1956) in typhus rickettsiae and by Myers et al. (1959) in Coxiella burnetii may have an important role in the protein metabolism of this parasite.