Structural Evaluation of Interleukin-19 Cytokine and Interleukin-19-Bound Receptor Complex Using Computational Immuno-Engineering Approach

Interleukin 19 (IL-19) is an anti-inflammatory cytokine that belongs to the IL-10 family, where IL-20 and IL-24 also exist. While IL-19 and IL-20 share some comparable structural folds, there are certain structural divergences in their N-terminal ends. To date, there are no reported IL-19 receptors; although, it has been suggested in the literature that IL-19 would bind to lL-20 receptor (IL-20R) and trigger the JAK-STAT signaling pathways. The present report examines the structure of the IL-19 cytokine and its receptor complex using a computational approach. Specifically, the postulated modes of interactions for IL-20R as an IL-19 receptor are examined on the basis of a set of computational findings. The author has used molecular docking and molecular dynamics simulation to generate a 3D model for the IL-19 complex with IL-20R. When a protein’s crystal structure is not available in the literature, predictive modeling is often employed to determine the protein’s 3D structure. The model assessment can be based on various factors, which include stability analysis using RMSD calculations, tracking changes in time-based secondary structures and the associated Gibbs energies, ΔG. Since one model complex (referred to as model A throughout this paper) can be used as a working hypothesis for future experiments, this structure has been explored here in detail to check its stability, subunit interfaces, and binding residues. The information gathered in this approach can potentially help to design specific experiments to test the validity of the model protein structure. Additionally, the results of this research should be relevant for understanding anti-inflammatory mechanisms and, eventually, could contribute to the efforts for therapeutic developments and targeted therapy.