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 Zn2+ 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 Zn2+ concentration to be elevated to 500 μM. As the threshold Zn2+ 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.

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