Gene controlling L-glutamic acid decarboxylase synthesis in Escherichia coli K-12

Genetically related Escherichia coli K-12 strains were found to differ widely in their l-glutamic acid decarboxylase (GAD) activity. This variation is due to differences in the amount of GAD produced by the different cultures, rather than to the appearance of altered enzymes differing in catalytic activity. A regulatory gene, gadR, which controls the amount of GAD was mapped on the E. coli K-12 chromosome. A strain with a lesion in the structural gene for GAD is described.