Harnessing microbial tools: Escherichia coli as a vehicle for neuropeptide functional analysis in Caenorhabditis...

Animals respond to changes in their environment and internal states via neuromodulation. Neuropeptides modulate neural circuits with flexibility because 1 gene can produce either multiple copies of the same neuropeptide or different neuropeptides. However, with this architectural complexity, the function of discrete and active neuropeptides is muddled. Here, we design a genetic tool that facilitates functional analysis of individual peptides. We engineered Escherichia coli bacteria to express active peptides, fed loss-of-function Caenorhabditis elegans, and rescued the activity of genes with varying lengths and functions: pdf-1, flp-3, ins-6, and ins-22. Some peptides were functionally redundant, while others exhibit unique and previously uncharacterized functions. We postulate our rescue-by-feeding approach can elucidate the functional landscape of neuropeptides, identifying the circuits and complex peptidergic pathways that regulate different behavioral and physiological processes.