Site directed mutagenesis of human Interleukin-2 gene to increase the stability of the gene product- A Bioinformatics Approach

Interleukin-2 (IL-2) is an immunoregulatory cytokine whose biological effects are mediatedthrough interaction with specific receptors on the surface of target cells. Due to its presumed role ingenerating a normal immune response, IL-2 is being evaluated for the treatment of a variety of tumors, inaddition to infectious diseases. Main drawback of human IL-2 is that the molecule is relatively unstable.Therefore, with the objective of increasing the stability of the molecule, site directed mutagenesis of humanIL-2 gene was carried out. Early studies indicated that mutations at three Cysteine residues (58, 105, 125)which are in the active sites of human IL-2 resulted in the reduced stability as well as the biological activity ofthe molecule. Therefore, mutations were carried out at the positions of amino acid other than the receptorbinding sites at 111Valine to Arginine, 117Lysine to Glutamine and 133 Threonine to Asparagine of thehuman sequence by comparing it with the bovine sequence which has higher stability than the humancounterpart, using SWISS PDB tool. To understand the biological activity of the mutated IL-2, energyminimization studies were carried out using SWISS-PDB. Docking studies were performed to check thereliability of the results using HEX DOCK, ARGUS LAB and PATCH DOCK between the IL-2 receptor andits mutated Ligand. These docking results also confirmed that the reliability of these mutated IL-2 gene.Stability, half life and ADME characteristics of these mutants can be studied in a detailed manner in the invivo studies.