Deciphering and harnessing promoter-driven feedback controllers to mitigate metabolic burden in Corynebacterium...

Metabolic burden arises from the reallocation of cellular resources, often resulting in stress-associated phenotypes and compromised cellular performance. However, the molecular mechanisms by which industrial microorganisms perceive and alleviate such burdens remain largely unexplored. Here, we present an online monitor to quantify metabolic burden imposed by genetic and environmental perturbations in the workhorse Corynebacterium glutamicum. RNA-seq analysis revealed a shared host response and enabled the identification of several early-responsive promoters through in vivo burden assays. Leveraging these elements, particularly the cg1940 promoter, we successfully engineered dynamic feedback systems to alleviate metabolic burden associated with suboptimal expression. Notably, the identified promoter retained burden responsiveness in Escherichia coli, suggesting potential cross-species applicability. As a proof of concept, this feedback controller was applied to improve cell growth, protein synthesis, and chemical bioproduction. This technology offers a strategy for bolstering the robustness of C. glutamicum and potentially other microorganisms.