Human Indoleamine 2,3-dioxygenase 1 (IDO1) Expressed in Plant Cells Induces Kynurenine Production

Abstract

Genetic engineering of plants has turned out to be an attractive approach to produce various secondary metabolites. Here, we attempted to produce kynurenine, a health-promoting metabolite, in plants of Nicotiana tabacum (tobacco) transformed by Agrobacterium tumefaciens with the gene, coding for human indoleamine 2,3-dioxygenase 1 (IDO1), an enzyme responsible for the kynurenine production because of tryptophan degradation. The presence of IDO1 gene in transgenic plants was confirmed by PCR, but the protein failed to be detected. To confer higher stability to the heterologous human IDO1 protein and to provide a more sensitive method to detect the protein of interest, we cloned a gene construct coding for IDO1-GFP. Analysis of transiently transfected tobacco protoplasts demonstrated that the IDO1-GFP gene led to the expression of a detectable protein and to the production of kynurenine in the protoplast medium. Interestingly, the intracellular localisation of human IDO1 in plant cells is similar to that found in mammal cells, mainly in cytosol, but in early endosomes as well. To the best of our knowledge, this is the first report on the expression of human IDO1 enzyme capable of secreting kynurenines in plant cells.

Decoding the Complex Crossroad of Tryptophan Metabolic Pathways

“…This opens the scenario to past and next generation of probiotics (live microorganisms, such as Lactobacilli, producing beneficial metabolites), prebiotics (substrates that are selectively utilized by host microorganisms) and postbiotics (non-viable bacteria products or metabolic by-products, such as indole-3-carboxaldehyde), all of which modulate the microbial signatures, especially via Trp metabolism, and confer an health benefit on the host. In this scenario, the production of Kyn in plants of Nicotiana tabacum transfected with human IDO1 appears extremely exciting [ 15 ].…”