Histidine Dissimilation in Streptomyces coelicolor

Abstract
A growth technique that allows strains of S. coelicolor to grow dispersed in defined liquid medium was devised and used to determine the pathway of histidine degradation by S. coelicolor. Enzymic, chromatographic and stoichiometric analyses indicated that histidine is dissimilated via N-formyl-L-glutamic acid. The enzymes for histidine utilization (hut) are induced when histidine or urocanate is included in the culture medium. Biochemical evidence suggested that urocanate, or a further metabolite, is the physiological inducer. Three hut mutants were isolated and characterized. Two of the mutants exhibit an uninducible phenotype, whereas the 3rd mutant appears to be defective in the structural gene for formiminoglutamate iminohydrolase. Haploid recombinant analysis was employed to locate all 3 mutations in the left empty region of the chromosomal map.