PURINE METABOLISM IN BACTERIA VI

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Abstract
Nine adenine-requiring mutants of Escherichia coli and Salmonella typhimurium lacking the bifunctional deacylating enzyme, adenylosuccinase, were compared with respect to their patterns of accumulation of the ribosylated forms of 5-amino-4-imidazole-N-succinocarboxamide (SAIC). The ribonucleoside of SAIC was excreted by all of the mutants; the ribonucleotide was found only with the 4 mutants of E. coli. The mutants differed from each other in the amounts and forms of the accumulated SAIC. The production of SAIC is under an inhibitory feed-back control, which is specific for adenine. One mutant, E. coli B-94, with an additional requirement for arginine produced a copious amount of the riboside of SAIC. Transductional analysis with Pl phage showed that the arginine requirement was the result of a second mutation and unrelated to the adenine requirement or to the excess accumulation. An enzymatic method for the assay of 5-amino-4-imidazole-N-succinocarboxamide ribonucleotide was developed.