Further studies on the formation of choline sulfate by bacteria

Cell extracts of Pseudomonas C12B synthesized choline sulfate (COS) from SO42-, choline chloride, and ATP. However, most of the COS-forming activity was found in culture medium supernatants of this bacterium, and that which remained with the cells was cell wall-associated. Enzyme release was independent of the carbon and (or) sulfur source used for growth and was not suppressed by increasing the divalent cation concentration of the medium. The COS-synthesizing system was inhbited in vitro by L-cysteine (greater than or equal to 10(-3) mM), SO42- (greater than 0.1 mM), and choline chloride (greater than 0.1 M). L-Cysteine (0.1-5.0 mM) did not repress the synthesis of enzymes present in the system. COS formation from SO42- in vitro was increased 2.8-fold by 10 mM adenosine 5'-phosphosulfate (APS) and 5-fold by 1 mM 3'-phosphoadenosine,5'-phosphosulfate (PAPS) during a 4-h incubation period. APS (10 mM) also inhibited the incorporation of 35SO42- into COS. Culture supernatants incubated with Na235SO4 produced two 35S-labelled metabolites having electrophoretic mobilities similar to those exhibited by authentic APS and PAPS. The synthesis of these metabolites was also inhibited in vitro by unlabelled APS and by L-cysteine.