Control of enzyme activity in growing bacterial cells by concerted feedback inhibition

Amino acids of the aspartic acid family are synthesized in bacteria through a multistep branched pathway. In the photosynthetic bacterium Rhodopseudomonas capsulatus, the enzyme that catalyzes the first step is specifically inhibited by a combination of two end-product amino acids. Evidence is presented for operation of this kind of "concerted" feedback control as a regulatory device in growing cells.