Metabolically robust autoluminescent reporters
Self-sustained luminescence can be engineered in non-luminous organisms by integrating luciferin biosynthesis pathways with the hosts metabolism. When conditionally expressed, such pathways enable non-invasive monitoring of virtually any transcriptional event, providing a wide dynamic range and high resolution. However, because light emission depends on substrate availability within the cell, autoluminescence reporters are inherently non-quantitative: signal intensity reflects both gene expression and cellular metabolism. Here, we present an approach that disentangles the contributions of gene expression and metabolism, rendering autoluminescence signals robust against metabolic perturbations. By co-expressing an engineered reference luciferase variant that uses the same substrate but emits light at a different wavelength, and monitoring the resulting colour ratio, we dramatically reduce signal variation, enabling quantitative physiological imaging amid changing metabolic activity. Our strategy is applicable across known autoluminescence pathways from bacteria and fungi.