Modification of response behavior of zinc sensing HydHG two-component system using a self-activation loop and genomic integration.

Characterizing the dynamics of HydHG-a two-component transcriptional regulatory network for exogenous zinc in E. coli-is essential in understanding the biology of these regulatory and signaling pathways. Here, we used a synthetic biology strategy to modify the dynamic characteristics of the HydHG network in two ways. First, a self-activation loop for HydHG network was created under the control of zraP promoter, after which the threshold Zn(2+) concentration for the self-activated HydHG network significantly decreased from 200 to 10 µM. Second, the self-activation loop was integrated into the E. coli genome allowing the threshold Zn(2+) concentration to be elevated to 500 µM. As the threshold Zn(2+) concentration could be modified in both directions, the introduction of a self-activation loop and the entire genomic integration strategy may prove useful for the creation of a two-component bacterial biosensor with varying sensitivities.