Metabolism of delta-Aminolevulinic Acid in Red and Blue-Green Algae.

delta-Aminolevulinic acid was incorporated in vivo into C-phycocyanin and B-phycoerythrin in two species of the Rhodophyta (Cyanidium caldarium, Porphyridium cruentum) and three species of the Cyanophyta (Anacystis nidulans, Plectonema boryanum, Phormidium luridum). Amino acid analysis of phycocyanin-(14)C from C. caldarium cells which had been incubated with delta-aminolevulinate-4-(14)C showed that 84% of the radioactivity incorporated was present in the phycocyanobilin chromophore and less than 16% of the radioactivity cochromatographed with amino acids. These results indicate that delta-aminolevulinate is utilized predominantly via the porphyrin pathway in C. caldarium. Conversely, analysis of phycocyanin-(14)C prepared from cells of A. nidulans, P. boryanum, and P. luridum which had been incubated with radiolabeled delta-aminolevulinate demonstrated that 85%, 81%, and 93%, respectively, of the radioactivity incorporated cochromatographed with amino acids. The ratio of incorporated radioactivity in amino acids and phycoerythrobilin was 40:60 in P. cruentum phycoerythrin obtained from cells which had been incubated with delta-aminolevulinate-4-(14)C. Succinate-2-3-(14)C appeared to be as good a carbon source of amino acids as did C(4) and C(5) of delta-aminolevulinate. These data demonstrate a major alternate route (other than the porphyrin pathway) of delta-aminolevulinate metabolism in red and blue-green algae. The factors responsible for the extent to which delta-aminolevulinate is utilized for synthesis of porphyrins and their derivatives and routes of delta-aminolevulinate catabolism in the organisms employed are discussed.