Derepression of arylsulfatase synthesis in Aerobacter aerogenes by tyramine

Studies were made on the effect of tyramine on arylsulfatase synthesis in mutants of Aerobacter aerogenes ATCC 9621 deficient in enzymes involved in tyramine degradation. As shown previously, some sulfur compounds, such as inorganic sulfate, repressed enzyme synthesis while others, such as methionine, did not. Tyramine caused derepression of enzyme synthesis, which is repressed by inorganic sulfate. The present work showed that, although tyramine readily derepressed arylsulfatase synthesis, metabolites of tyramine in either the wild-type or mutant strains did not, so that the derepression is due to the particular structure of tyramine. Kinetic studies on the cells indicated that incorporation of sulfur into protein and enzyme synthesis occurred on supply of either a sulfur compound, which did not cause repression, or of tyramine, which caused derepression, irrespective of the type of sulfur compound added, if any.