Expression of the genetically engineered E. coli in response to histidine starvation

Stochastic switching of a monostable circuit mediated the adaptation of the engineered OSU12-hisC Escherichia coli strain to histidine starvation. In this strain, the hisC gene was deleted from the His operon and placed under the control of a monostable foreign promoter. In response to histidine depletion, the OSU12-hisC population shifted to a higher HisC expression level, which are beneficial under starving conditions but are not favoured by the monostable circuit. Microarray analysis indicated that OSU12-hisC reorganised its transcriptome to reach the appropriate physiological state upon starvation. The study suggests that bacteria do not necessarily need to evolve signalling mechanisms to control gene expression appropriately, even for essential genes. The hisC rewired strain and the control strain exponetially grown in the presence and absence of histidine were collected for the transcriptional analysis. Every 3 biological replications for each condition were performed.