Engineered Regulatory Systems Modulate Gene Expression of Human Commensals in the Gut

Abstract

The gut microbiota is implicated in numerous aspects of health and disease, but dissecting these connections is challenging because genetic tools for gut anaerobes are limited. Inducible promoters are particularly valuable tools because these platforms allow real-time analysis of the contribution ofmicrobiome gene products to community assembly, host physiology, and disease. We developed a panelof tunable expression platforms for the prominent genus Bacteroides in which gene expression is controlled by a synthetic inducer. In the absence of inducer, promoter activity is fully repressed; addition of inducer rapidly increases gene expression by fourto five orders of magnitude. Because the inducer is absent in mice and their diets, Bacteroides gene expression inside the gut can be modulated by providing the inducer in drinking water. We use this system to measure the dynamic relationship between commensal sialidase activity and liberation of mucosal sialic acid, a receptor and nutrient for pathogens. VIDEO ABSTRACT.