Modelling of fish interleukin-1 and its receptor.

This paper presents original data regarding: the three-dimensional modelling of rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax) IL-1beta, the modelling of trout IL-1 receptor type I (IL-1RI) and the modelling of trout IL-1beta bound to its receptor. The 3D models of trout and sea bass IL-1beta molecules were predicted by comparison with those already available of human and mouse, and, in both cases, a structure consisting of a beta-trefoil fold was obtained, a motif well conserved during evolution of IL-1beta-related proteins. Moreover, a model for the rainbow trout IL-1 receptor alone and complexed with IL-1beta was predicted and compared to the murine model. Both ligand-receptor complex models were compared with the known crystal structure of the human IL-1beta/IL-1R complex. A cross-interaction of trout IL-1beta with the mouse receptor was also simulated. Such analysis and the predicted interaction energies calculated from the models have helped to explain the different biological efficacies of mammalian and fish IL-1beta molecules in assays based on mammalian target cells. The obtained data are discussed on the basis of evolutionary and applied perspectives.