Single nucleotide polymorphism and asthma: from conformational variations to structural alternations

Abstract

Background: Asthma is the main reason of disability, health resource exploitation and low quality of life for those who are affected. It is estimated that nearly 300 million people in the world are suffering from asthma. Studies have identified 18 genomic regions and more than 100 genes associated with asthma. Among these candidate genes, IL-17F plays a very interesting role in asthma. This study was conducted to predict the conformational and functional impact of asthma-associated IL-17F polymorphisms on protein product of the corresponding gene using Phyre2, PolyPhen2 and SIFT softwares. Methods: In the present study, 10 significant missense SNPs (rs763780, rs144576902, rs11465553, rs368500268, rs141798304, rs2397084, rs146083682, rs200163061, rs376671742, and rs373228601) were taken from Ensembl Genome Browser database. Polymorphism-induced protein structural changes were predicted using Protein Homology analogY Recognition Engine V2.0 (PHYRE2) program. The possible impact of an amino acid substitution on the function of protein was analyzed using PolyPhen-2 (Polymorphism Phenotyping Version2) and SIFT (Sorting Intolerant From Tolerant) tools. Results: The analysis revealed mutant proteins having structural changes in the number of atoms, H-bonds, turns and helices. While wild copy has 82 H-bonds, 5 helices and 20 turns, the mutant types show considerable changes. At functional level also, substantial changes were observed between the wild protein and the mutant one. Conclusion: A single nucleotide polymorphism in the gene sequence can lead to the substantial structural and functional variations in the protein product of the gene, a process that may account for etiology of a number of complex diseases including asthma.